The United Kingdom s official Incident Data Report focussing on carbon monoxide deaths and serious incidents, from piped natural gas and liquid petroleum gas (LPG) during 2009/10. Carbon Monoxide Hotspot Report Carbon Monoxide Incident Report
Working in partnership A review of carbon monoxide incident information, for 2009/10, produced from the full investigation of incidents which involved piped natural gas and LPG, within Great Britain Funded by: The Gas Safety Trust www.gas-safety-trust.org.uk Prepared by: Downstream Gas J Hayton M Moore J Moseley G Pool This report has been funded by The Gas Safety Trust as a continuation of the work established during a Joint Industry Programme (JIP) addressing carbon monoxide (CO) issues in 1996. This work identifies common concerns involved in carbon monoxide incidents related to appliance and system design, the home environment, installation, servicing and maintenance. The conclusions reached are intended to help further improve safety, to target investment on carbon monoxide incident prevention and to identify additional research work. This is the fourteenth report in a series that began with the publication of a first annual report in 1996 and covers the 12 months between 1st July 2009 and 30th June 2010. During this period details of 56 domestic piped gas incidents and one LPG incident were submitted to Downstream Gas and their analysis constitutes the main part of the report. Details of a further three incidents that occurred before July 2009 were also received and these are included in Appendix C and in the revised historical figures within the main body of the report. Given that four incidents in the Cardiff (CF) postcode area were also noted in the 2007/8 reporting period, this suggests that the Cardiff postcode area may be an incident hotspot. Possible reasons for this might include a greater public awareness of carbon monoxide among the local population or poorer standards of installation and levels of maintenance. The Gas Safety Trust believes the information and data contained within to be crucial to the further reduction of death or serious injury from accidental carbon monoxide exposure and to be more user friendly. The data contained within this report has been confirmed and verified with the Health and Safety Executive relating to fatal carbon monoxide incidents reportable under RIDDOR 6(1), 1995 during the period 1st July 2009 to 31st June 2010. Gas Safety Trust Carbon Monoxide Incident Report 2010 i
Contents Executive summary....................................... 1 1 Introduction...................................... 3 1.1 Context.............................................. 3 1.2 Scope............................................... 3 1.3 Coverage............................................. 5 2 Analysis of DIDR forms................................ 7 2.1 Preliminary overview........................................ 7 2.3 Casualty Details - Section 2 of DIDR............................... 9 2.4 Incident Location Details Section 3 of DIDR.......................... 14 2.5 Casualty & Appliance Location Section 4 of DIDR....................... 18 2.6 Incident Appliance Details - Section 5 of DIDR.......................... 20 2.7 Details relating to individual appliance types and models.................... 27 2.8 Appliance Installation Details Section 6 of DIDR........................ 30 2.9 Flue Details Section 7 of DIDR................................. 30 2.10 Permanent Ventilation Section 8 of DIDR............................ 32 2.11 Safety Devices Section 9 of DIDR............................... 33 2.12 On-site Checks Section 10 of DIDR.............................. 33 2.13 Incident Appliance History Sections 11 and 12 of DIDR.................... 35 2.14 Incident Cause/Causes - Section 13 of DIDR.......................... 37 3 Conclusions and recommendations........................ 39 4 References......................................41 Appendix A: DIDR LPG incidents...............................42 Appendix B: DIDR non-domestic incidents..........................42 Appendix C: Past incidents previously unreported...................... 43 Gas Safety Trust Carbon Monoxide Incident Report 2010 ii
Tables and figures Figure 1: Monthly incident numbers..................................... 8 Figure 2: Monthly casualty numbers.................................... 8 Table 1: Classification of non-fatalities................................... 9 Figure 3: Reported incident and casualty numbers............................. 9 Table 2: Carbon monoxide incident numbers and risk rates for 1st July 2009 to 30th June 2010..... 10 Table 3: Yearly data (July 1st to June 30th)................................ 10 Figure 4: Fatality trends.......................................... 11 Figure 5: Incident trends......................................... 11 Figure 6: Fatality age profile........................................ 12 Figure 7: Casualty age profile....................................... 12 Table 4: Properties with a boiler by occupancy type (England 2008/9).................. 14 Figure 8: Incidents by occupancy type.................................. 14 Table 5: English dwelling makeup by built form.............................. 15 Figure 9: Incidents by dwelling type.................................... 15 Table 6: Estimated national breakdown by property construction period................. 16 Figure 10: Incidents by property construction period............................ 16 Figure 11: Incidents by glazing details................................... 17 Table 7: Incidents by floor construction................................. 17 Table 8: Incident appliance location by floor level............................. 18 Table 9: Appliance and casualty locations................................ 19 Figure 12: Incident appliances installed in compartments.......................... 19 Figure 13: Incidents by appliance type................................... 20 Figure 14: Incidents by central heating type................................. 21 Table 10: Projected boiler populations by type (England, Dec 2009).................... 21 Figure 15: Reported and expected incident numbers by boiler type..................... 22 Figure 16: Incidents by boiler age...................................... 23 Table 11: Relative risk by boiler age (base case 10 years old or less).................... 23 Table 12: Incident numbers by appliance age............................... 24 Figure 17: Fatalities by appliance type................................... 24 Table 13: Incident data for central heating boilers............................. 25 Table 14: UK cooking appliance population estimates........................... 25 Table 15: Incident data for cookers.................................... 26 Table 16: Appliance installation details................................... 30 Figure 18: Incidents by flue type...................................... 31 Figure 19: Incidents by flue standards................................... 32 Table 18: Incidents reported with obstructed ventilation.......................... 33 Figure 21: Reported faults by type..................................... 34 Table 19: Incident appliance faults..................................... 34 Table 20: Details of service history..................................... 35 Table 21: Details of last working visit.................................... 35 Table 22: Interval between the last working visit and the incident...................... 36 Figure 22: Distribution of the number of stated causes........................... 37 Figure 23: Reported causes........................................ 37 Gas Safety Trust Carbon Monoxide Incident Report 2010 iii
Executive summary This report builds on the work initiated during a Joint Industry Programme in the 1990s which was concerned with accidental carbon monoxide (CO) poisoning in Great Britain associated with the use of piped natural gas and LPG in the home. The report presents information provided using Downstream Incident Data Report (DIDR) forms completed following carbon monoxide incident investigations. A statistical analysis has been undertaken of the contributory factors and the installations to help establish national and yearly trends 1. The aim of any conclusions is to help further improve safety. This is the fourteenth annual report and covers the period from 1st July 2009 to 30th June 2010. The main focus of the analysis of incident information relates to domestic piped natural gas with details of any reported incidents involving LPG and non-domestic use of gas received from incident investigators presented in appendices. There was one such LPG incident reported this year and no non-domestic DIDR reports were received. For the current reporting year, 4 accidental fatalities occurred relating to natural gas. This was the lowest annual figure reported since records started to be published in 1996 despite the coldest winter in England/ Wales since 1978/9. The substantial reduction in fatalities since 2008/9 when 17 were reported was due in part to last year s total including 7 involving gas cookers. The winter of 2009/10 was the coldest since 1978/9 and the previous winter was the coldest since 1995/6. The number of carbon monoxide incidents associated with domestic natural gas use reported during 2009/10 was 56 involving 115 casualties. This is similar to last year s figures of 57 and 97 respectively and is well within the trend 1 observed since 2001. One possible reason why fewer fatalities are being reported now compared to 5 years ago may be linked to the predominance of room-sealed condensing boilers now required by law to be installed as new or replacement appliances. The condensing boiler population is estimated to have risen from 2% of all boilers in domestic use in 2001 to 5% in 2005 and is 25% today. Based on an estimated 51.6 million people in Great Britain (GB) in 2009 living in households with natural gas as the main fuel, the risk of an incident occurring was 1.09 per million people at risk; this corresponds to 0.08 fatalities per million people at risk per year and 2.23 casualties (non-fatal) per million people at risk per year. Nearly 25% of the reported casualties in 2009/10 were categorised as less severe (not hospitalised). This is a similar proportion to last year (2008/9) and compares to an average of only 11% prior to 2008/9. It indicates a higher proportion of incidents are being identified before serious injury takes place and this may be due to an increased use of carbon monoxide detectors. 1 The trend is a moving average over three years centred on the middle year. Gas Safety Trust Carbon Monoxide Incident Report 2010 1
Analysis of those incidents involving boilers concluded that those between 11 and 20 years old were 50% more likely to be involved in an incident than newer boilers and that those over 20 years old were 20 times as likely to be involved in an incident than those 10 years old or newer. This highlights the importance of the need to service and maintain older boilers in accordance with the manufacturer s instructions. Downdraught sensors, anti-vitiation devices and carbon monoxide detectors were being used at 16 out of the 19 incident sites where safety device information was reported. This suggests there has been a steady increase in the use of detectors over the last 10 years. There is evidence to indicate that such devices have been alerting gas users to a developing unsafe situation before injury to occupants has occurred, that is before a RIDDOR reportable incident has arisen. During 2009/10, two fatal incidents occurred and each was after working visits made by a gas operative less than 6 months beforehand. Warning notices had been left by the operatives but the advice/instruction given had not been implemented by the responsible person at the property. Just over half of the incident reports received stated a working visit had been made by a gas operative to the property within a year prior to the incident. It is known that on four separate occasions, warning notices had been issued but the person responsible for the property had failed to take the appropriate action and two fatalities resulted. This suggests a review of the warning notice classification scheme may be required. Additionally, it seems some operatives may not have been noting indications that an installation was deteriorating at the time of their visit. It was revealed that 4 incidents had occurred in the Cardiff postcode area and this may mean it is a hotspot for carbon monoxide incidents. The main causes of incidents reported this year can broadly be summarised as follows: i) Lack of servicing was the most common cause specified ii) Inappropriate flue/terminal positioning iii) Unsafe connections between appliances and flue systems iv) Misuse of appliances and interference with the associated ventilation provision by tampering with appliances (removing covers), blocking air intakes and in one instance, using a damaged cooker when it had previously toppled over Gas Safety Trust Carbon Monoxide Incident Report 2010 2
1 Introduction 1.1 Context Downstream Incident Data Report (DIDR) forms are completed by investigators following the investigation of accidental carbon monoxide (CO) poisoning in Great Britain from the use of piped natural gas or LPG in the home. The information received has been gathered, placed on a database, analysed and presented in a series of thirteen consecutive annual reports from 1996/7 to 2008/9. The initial reports were funded by the Health and Safety Executive (HSE) with the CORGI Trust taking over the funding for the reporting period starting April 2006. This is the fourteenth report and the third produced by Downstream Gas for The Gas Safety Trust (formerly The CORGI Trust). It covers the 12 months between 1st July 2009 and 30th June 2010. 1.2 Scope The gas industry has clear mandatory obligations and responsibilities in terms of reporting gas related carbon monoxide incidents. These are specified in the Gas Safety Management Regulations (GSMR) 1996 and in particular place duties upon the supplier of mains natural gas and piped LPG. The GSMR state that: where an incident notifiable under regulation 6(1) of the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 has arisen as a result of an escape of carbon monoxide (CO) from incomplete combustion of gas in a gas fitting, the person who supplied the gas shall, as soon as is reasonably practicable after receiving notice of the incident, cause an investigation to be carried out so as to establish, so far as is reasonably practicable, the cause of the escape and accumulation of the carbon monoxide gas. The Regulations are known as RIDDOR. Regulation 6(1) states that: Whenever a conveyor of flammable gas through a fixed pipe distribution system, or a filler, importer or supplier (other than by means of retail trade) of a refillable container containing liquefied petroleum gas receives notification of any death or major injury which has arisen out of or in connection with the gas distributed, filled, imported or supplied, as the case may be, by that person, he shall forthwith notify the Executive of the incident, and shall within 14 days send a report of it to the Executive on a form approved for the purposes of this regulation. The Executive is the Health and Safety Executive. The Guidance to Regulation 6(1) states that: The trigger for a report to the HSE under regulation 6(1) is the receipt by the person on whom the reporting duty is placed of notification of a flammable gas incident causing a death or a major injury other than one reportable under regulation 3(1). Gas Safety Trust Carbon Monoxide Incident Report 2010 3
Regulation 3(1) relates to death or major injury as a result of an accident arising out of or in connection with work whether or not the person was at work. It also covers hotel or care home residents, pupils or students and customers in shops. In general it may be interpreted that for the understanding of this report, Regulation 6 (1) covers domestic premises. As specified in GSMR, a carbon monoxide incident has to fulfil specific criteria in order to be formally reported. Such an incident is notifiable under regulation 6(1) of the Reporting of Injuries, Diseases and Dangerous Occurrences Regulations 1995 and for this reason is frequently known as a RIDDOR reportable incident. Primarily, following the inhalation of a substance (in this case carbon monoxide) the incident has to result in: an acute illness requiring medical treatment or a loss of consciousness An acute illness means: one that progresses rapidly to a crisis after the onset of symptoms and has severe symptoms Medical treatment covers: hospital treatment treatment by a general medical practitioner or treatment by a firm s medical and nursing staff Treatment by a paramedic is also included here. An interesting aside is that there were five investigations initiated following carbon monoxide alarms sounding that had no reported injuries and therefore excluded from the analysis. However, they do highlight that the carbon monoxide alarms are doing their job alerting occupants of potential danger before the carbon monoxide levels rise to harmful levels. Based on the gas industry s duty to investigate carbon monoxide related incidents, the DIDR process was setup to achieve the systematic gathering of details from incident investigations in order to help identify trends and common underlying features. Incidents that occur in domestic properties attached to shops, offices, restaurants, etc are only included if the causes were related to the domestic use of gas. Incidents involving multiple residential properties such as student accommodation and sheltered housing are included but care homes are excluded as the latter are work related. Occasionally DIDR forms are completed for incidents occurring in non-domestic premises so for completeness, any received are included in a separate Appendix and these details will not feature in the statistical analysis of data covered in the main body of the report. The reporting of LPG incidents via the DIDR forms is limited to those associated with refillable LPG tanks or cylinders. Incidents related to portable LPG are not RIDDOR reportable. An incident investigation and systematic reporting scheme for heating oil, kerosene and solid fuel, based around the gas forms, started in July 2010 (this being an across industry co-ordination between the Gas Safety Trust, OFTEC and HETAS). Gas Safety Trust Carbon Monoxide Incident Report 2010 4
The statistics in the main body of report: Include data on DIDR forms received relating to the domestic use of piped natural gas. Exclude any DIDR forms received detailing carbon monoxide incidents associated with LPG or piped natural gas in a non-domestic situation. However, for completeness any data received on DIDR forms is presented in appendices to the report. 1.3 Coverage The information gathered during an incident investigation relies on the investigators working on behalf of gas suppliers completing a DIDR form for each carbon monoxide incident and sending it to Downstream Gas for entry onto the database. Fatalities resulting from those incidents confirmed to have been caused by exposure to carbon monoxide and reported to Downstream Gas via DIDR forms have been reconciled with information recorded by the HSE. The primary aim of the work is to examine in detail the circumstances of all carbon monoxide incidents to reveal any common concerns and conclusions that will help to improve gas safety in the future. It is therefore important that detailed investigations are carried out on as many incidents as possible that meet the criteria for an investigation by law. There is a duty in law on the gas supplier to carry out such investigations and if it should be recognised by both HSE Inspectors and the gas suppliers alike that, this needs to happen irrespective of whether the HSE intends to take any further action or not. For the period 1st July 2009 to 30th June 2010, 56 natural gas and one LPG incidents (see Appendix A) were reported to Downstream Gas of which 11 were short reports; these short reports only feature brief details including the incident date, geographical location, casualty details (Section 1 and 2 of the form) and the suspected cause and type of appliance. In a full report, additional sections contain detailed information about the appliance installation and dwelling characteristics. Full reports were received for 45 out of the 56 reported incidents (80%). Detailed information remains unknown for 11 of the 56 incidents. Reasons given for being unable to provide detailed reports include: - Investigation still on-going (1) Appliance removed or installation fixed before investigation could take place (7) Incident condition not preserved (1) The boiler cover had been removed by the occupant and the HSE indicated no further action was necessary (1) Gentleman found collapsed whilst cooker lit. Operative capped gas supply to cooker and left (1). The detailed completion rate (80%) for 2009/10 was higher than recent years (68% last year) 2 and shows the efforts to encourage full detailed reporting have been somewhat successful. The main reason for the lack of detailed investigation was that the appliance was fixed or removed before investigation could take place. There is still room for improvement in the detailed completion rate because even if an appliance has been repaired before the investigation it is still worth supplying most of the other detailed information (eg use of safety devices, frequency of servicing, type of appliances) even if an assessment of the appliance in the as found condition cannot be carried out at the incident site. There may be other occasions when a report is delayed, for example whilst waiting on the result of an inquest or a trial. DIDRs of three incidents occurring before July 1st 2009 were received after the analysis for 2008/09 was completed; these comprised a double fatality involving LPG, a double fatality involving natural gas and one nonfatality involving natural gas. These are reported in detail in Appendix C. 2 Ref 13. Gas Safety Trust Carbon Monoxide Incident Report 2010 5
The double fatality involving natural gas was included in last year s fatality numbers as brief details were given by the HSE to Downstream Gas. Therefore, last year s corresponding figures relating to natural gas have been increased by one incident and one non-fatality and the appropriate amendments have been made to the historical figures, charts and tables in the main body of this report. The net effect on the overall figures associated with natural gas for 2008/9 is that incidents were up by 1 to 57, casualties up by to 1 to 97 and fatalities unaltered at 17. The double fatality associated with natural gas highlighted a known issue concerning room-sealed pressurised case appliances when they are not properly serviced or maintained (see part 2.14 and incident 1 Appendix C). The third incident for the reporting period 08/09 was a double fatality involving the use of an LPG appliance and details are provided in Appendix C. After reconciling the number of fatal incidents reported by British Gas, CORGI Services and the Gas Safe Register with those recorded by the HSE, the information provided to Downstream Gas in the DIDR forms was analysed and is presented in this report. Tables and charts are included relating to the numbers of reported fatalities, nonfatalities and incidents. Also, where appropriate the expected number in a specific category is given assuming the number of incidents in each category is in the same proportion to that of the category in the general population. As an example, if, hypothetically, there were 40 female and 20 male non-fatalities, the expected number if both were equally at risk would be 30 each as the general population is split almost 50:50 between male and female. The risk of accidental carbon monoxide poisoning associated with the use of natural gas in the home has been calculated and expressed in terms of fatalities, casualties or incidents per million people potentially at risk per year. People considered potentially at risk are those living in properties with at least one gas appliance (i.e. those supplied with mains natural gas nationwide). Risk rates associated with particular appliance types have been estimated by taking the number of people at risk as those living in homes with the particular appliance type installed. In order to reveal the annual trends, fatality, casualty and incident rates are also presented for the fourteen yearly periods starting from the 1st July 1996. Section 2 of this report analyses data in the same sequence as it is featured on the DIDR form and interprets information making use of appliance population statistics, where available. Section 3 then draws conclusions and lists recommendations where appropriate. Appendix A is intended for domestic LPG incidents reported to Downstream Gas on the DIDR form. One incident was reported this year following an investigation by the Gas Safe Register. Appendix B is intended for non-domestic incidents should they be reported to Downstream Gas on the DIDR form. No such incidents were reported this year. Appendix C is intended for details of incidents that occurred in previous years for which information was made available this year. Details of two natural gas incidents and one LPG incident were received this year although they happened last year. Historical data and charts in the main body of this report have been updated accordingly. Gas Safety Trust Carbon Monoxide Incident Report 2010 6
2 Analysis of DIDR forms 2.1 Preliminary overview There were 57 domestic incidents reported on DIDR forms that met the criteria for inclusion during the 12 month reporting period (1st July 2009 to June 30th 2010). The criteria that have to be met have been specified in Section 1.2. Confirmation that the victim or victims were exposed to excessive levels of carbon monoxide is typically obtained via blood tests or that an installation was shown to be producing dangerous levels of carbon monoxide when examined in the as found condition. Deliberate acts such as suicides are excluded. All but one reported incident related to mains natural gas use. The exception involved the use of LPG from refillable fuel tanks or cylinders and details of this incident are given in Appendix A. All domestic carbon monoxide incidents referred to in this report were a result of natural gas usage unless otherwise stated. Carbon monoxide incidents are usually notified directly to British Gas and CORGI Services both of whom provide an investigation service to a number of gas suppliers. This year, at the request of the HSE, Gas Safe Register has investigated one incident related to natural gas use in addition to the incident involving LPG. All of the 56 incidents involving natural gas reported to the HSE had been notified to British Gas, CORGI Services or the Gas Safe Register. Incident Co-ordinators from each organisation liaise with each other to ensure the HSE is aware of all incidents and that they are investigated if they meet the RIDDOR reporting criteria. Of the 56 natural gas domestic incidents reported, 45 were fully reported. Information on the remainder was supplied on short (or less detailed) reports. Thus, whilst for 56 cases the analysis covers incident date, casualty information and main appliance data (see sub-sections 2.1, 2.2 and 2.6), for 45 of these the analysis was more comprehensive and covered, for example, incident appliances, flues, ventilation provision, appliance operation and servicing (Sections 2.3-2.13 inclusive). Each DIDR form completed and submitted by an investigator is dedicated to a separate carbon monoxide incident. The incident rates and yearly trend data have been combined with the casualty information and are described below in Section 2.2 Incident Details. Details of two domestic natural gas incidents and one LPG incident that occurred before July 1st 2009 were received after last year s analysis had been completed. All relevant incident information was supplied in full detail and the data is presented in Appendix C. This additional information has been incorporated into historical figures, charts and tables in the main body of this report. Each of the following Sections includes an assessment of the information retrieved from the carbon monoxide incident database for 2009/10 and, where appropriate, a discussion of the data. This discussion may relate this year s information with that from previous years or qualify this in terms of a wider context. Gas Safety Trust Carbon Monoxide Incident Report 2010 7
2.2 Incident Details - Section 1 of DIDR The numbers of carbon monoxide incidents recorded each month, ie those involving fatal and/or non-fatal casualties between 1st July 2009 and 30th June 2010 inclusive, are plotted in Figure 1. Figure 2 shows how these monthly figures break down in terms of the fatalities and non-fatal injuries reported. The so-called heating season, the period during which the majority of carbon monoxide incidents tend to occur, typically runs between September/October and April/May. Figure 1: Monthly incident numbers 14 13 Number of reported incidents 12 10 8 6 4 2 2 1 11 10 5 5 4 4 1 0 July August September October November December January February March April May June Figure 2: Monthly casualty numbers 40 35 30 25 20 15 10 5 4 Non fatal 1 Fatal 26 1 21 34 2 7 11 5 5 2 July August September October November December January February March April May June Number of reported casualties For the period 1st July 2009 to 30th June 2010 there were 56 separate carbon monoxide incidents reported. These affected 119 people, of whom 4 died. The number of fatalities has been reconciled with figures recorded by the HSE. 2.2.1 Geographic coverage Four incidents occurred in the Cardiff (CF) postcode area and three within CF16. The Cardiff postcode area covers a population of 962,000 in 408,000 households and has an incident rate of nearly 5 times the national average. This postcode area also has a population twice that of the national average. The chance of any postal area (119 in England, Scotland and Wales) similar in size to that of Cardiff having 4 or more incidents is 0.137. Even though Gas Safety Trust Carbon Monoxide Incident Report 2010 8
this is low, it is not statistically significant. The usual criterion for statistically significance is when the probability is below 0.025. 2.3 Casualty Details - Section 2 of DIDR A breakdown of those persons (115) reported as having been injured but not killed by carbon monoxide poisoning during the reporting period 2009/10 is presented in Table 1 and in Figure 3, with the severity of the casualties classified into four groups. Table 1: Classification of non-fatalities Classification N1 N2 N3 N4 Not stated Total Number of casualties 25 56 15 9 10 115 Table Notes: The classifications N1 to N4, as used on the DIDR form, are: N1 requiring immediate hospitalisation for more than 24 hours N2 requiring immediate hospitalisation for less than 24 hours, and/or hospital tests N3 requiring other medical treatment (e.g. GP or Paramedic) N4 receiving no medical treatment (e.g. treatment refused) Figure 3: Reported incident and casualty numbers Reported number 140 120 100 80 60 40 20 Unclassified N4 N3 N2 N1 Non-fatal Fatal 0 Incidents Victim Table 2 shows the likelihood of someone being involved in a carbon monoxide incident. The risk rates were calculated by dividing the number of incidents, casualties or fatalities by the number of people at risk. The exact number of people at risk is open to debate but in this report, it has been taken to be the number of people that live in homes with at least one gas appliance (i.e. the number of households with mains gas multiplied by the average number of people living in a household). Gas Safety Trust Carbon Monoxide Incident Report 2010 9
The calculated risk presented in Table 2 uses the following population information: a) The number of households using mains natural gas for December 2009 was 21.7 million (85.7% 3 of 25.3 4 ) and this figure is slightly lower than the 22.3 million reported for 2008/9. Last year s figure was based on gas users with a consumption of 73,200 kwh (2,500 therms) or less in December 2007 which will include some non-domestic users (eg small shops and offices). This year it has been based on the latest GB household population in December 2009 and the percentage of homes in England with gas as the main fuel (December 2007 5 ). This year s estimate is considered to be better as the percentage of homes with gas is unlikely to have changed significantly over the last two years given the number of new homes built each year is only about 0.6% of the existing population. b) The average number of people per household in Great Britain for mid-2009 was 2.38 6 (the latest available figures). As in previous reports this assumes the number of people per household with at least one gas appliance is the same as that for the population as a whole. Table 2: Carbon monoxide incident numbers and risk rates for 1st July 2009 to 30th June 2010 Total Numbers of people affected Incidents, fatalities or casualties per million people at risk per year Incidents Fatal Non-fatal Incident Fatality Non-fatal 56 4 115 1.1 0.08 2.40 The risk values calculated for the 13 years previously reported are given in Table 3 and these figures include the one case notified after the 2008/9 report had been published. Yearly trends recorded in fatality and incident rates are also shown in Figures 4 and 5 respectively. The trend is defined as a moving average over three years centred on the middle year. Table 3: Yearly data (July 1st to June 30th) Reporting year Number Overall rate per million people per year Incidents Fatalities Casualties Incidents Fatalities Casualties 96/97 75 21 176 1.63 0.46 3.83 97/98 93 24 198 2.04 0.53 4.35 98/99 108 24 237 2.30 0.51 5.05 99/00 69 23 147 1.52 0.51 3.24 00/01 85 17 193 1.87 0.37 4.25 01/02 53 11 108 1.14 0.24 2.32 02/03 35 11 60 0.73 0.23 1.25 03/04 38 8 85 0.81 0.17 1.82 04/05 27 7 48 0.57 0.15 1.01 05/06 18 11 20 0.38 0.23 0.42 06/07 29 7 60 0.59 0.14 1.22 07/08 43 12 68 0.81 0.23 1.28 08/09 57 17 97 1.05 0.31 1.80 09/10 56 4 115 1.1 0.08 2.40 Note: incident rates for 2008/09 have changed marginally since last year s report was published because better demographic information is now available for December 2008. 3 Table SST6.1, English House Condition Survey 2007, Ref 6. 4 GB Q2 2009 (table 2.1 Social Trends Survey, Ref 5 projected forward six months. 5 Table SST6.1, English House Condition Survey 2007, Ref 6. 6 60 million people in GB (Mid 2009 Ref 5) 25.2 million households in GB Q2 2009 (table 2.1 Ref 5) Gas Safety Trust Carbon Monoxide Incident Report 2010 10
Figure 4: Fatality trends Fatalities (number) 30 25 20 15 10 5 Fatalities Trend Fatality rate Trend 1.20 1.00 0.80 0.60 0.40 0.20 rate per million people per year 0 Jul 96-Jun 97 Jul 97-Jun 98 Jul 98-Jun 99 Jul 99-Jun 00 Jul 00-Jun 01 Jul 01-Jun 02 Jul 02-Jun 03 Jul 03-Jun 04 Jul 04-Jun 05 Jul 05-Jun 06 Jul 06-Jun 07 Jul 07-Jun 08 Jul 08-Jun 09 Jul 09-Jun 10 0.00 Figure 5: Incident trends Number of incidents 120 100 80 60 40 20 Incidents Trend Incident rate Trend 4.2 3.5 2.8 2.1 1.4 0.7 Rate per million person per year 0 0.0 Jul 96-Jun 97 Jul 97-Jun 98 Jul 98-Jun 99 Jul 99-Jun 00 Jul 00-Jun 01 Jul 01-Jun 02 Jul 02-Jun 03 Jul 03-Jun 04 Jul 04-Jun 05 Jul 05-Jun 06 Jul 06-Jun 07 Jul 07-Jun 08 Jul 08-Jun 09 Jul 09-Jun 10 2.3.1 Casualty ages The age ranges of people injured fatally and non-fatally are presented in Figures 6 and 7 respectively. These ranges have been deliberately chosen to represent age groups with perceived differing vulnerabilities and potential for exposure to carbon monoxide. The expected numbers of incidents by age range is also shown in Figures 6 and 7. The expected number is the percentage of those within each age range resident in GB in mid-2009 (the latest available figures) obtained from the Office for National Statistics (ONS) 7 multiplied by the total number of casualties with an age recorded. In effect, the expected number is the average number that would occur if all ages were equally susceptible to and exposed to the same level of risk. 7 18.6%, 12.1%, 52.9%, 16.4% respectively Table 1.4, Social Trends Survey, Ref 5. Gas Safety Trust Carbon Monoxide Incident Report 2010 11
Figure 6: Fatality age profile 3.5 3.0 3 Reported number of fatalities Expected number of fatalities 2.5 Number 2.0 1.5 1.6 1.0 0.5 0.6 0.4 0.5 1 0.0 under 16 16 to 24 25 to 64 65 and over Age not stated Age range of fatalities Figure 7: Casualty age profile 60 50 Reported number of non-fatalities Expected number of non-fatalities 46.6 Number of people 40 30 20 10 19 16.4 11 10.6 39 19 14.4 27 0 under 16 16 to 24 25 to 64 65 and over Age not stated Age range of casualties 2.3.2 Discussion This year and last year nearly 25% of casualties reported were categorised as less severe (N3 or N4). This is a higher proportion compared to recent years (the average prior to 2008/9 was 11%) and possible explanations for this may be that occupants are being alerted before symptoms become severe, possibly from an increased use of audible carbon monoxide alarms, or there is now a general increase in the awareness of carbon monoxide symptoms. The overall number of fatalities averaged nearly 25 per year for the year commencing the 1st July in 1997, 1998 and 1999. Subsequently, it declined quickly to 10 per year, due to measures introduced such as the responsibility for gas safety placed on Landlords and the introduction of minimum efficiency limits on new boilers which has promoted an increase in the number of room sealed appliances installed since 1998. The downward trend levelled out during the following years. The four fatalities reported this year is just over half the previous low (seven in 2004/5 and in 2006/07). The considerable drop in numbers in 2009/10 has to some extent been accentuated by the significant number of fatalities reported last year that were attributed to the misuse of cooker grills. Gas Safety Trust Carbon Monoxide Incident Report 2010 12
The low number of fatalities occurred despite the cold winter. England and Wales experienced the coldest winter since 1978/79. In Northern Ireland and Scotland, the winter was as cold as 1978/79 and 1946/47, with only the 1962/63 winter having been significantly colder since records began in 1910. 8 Discounting the current year (2009/10), the average number of fatalities per year since 2001/2 has been 10. A Poisson distribution is used for accident type data when incidents are independent and such a distribution of mean 10 fatalities per year has an expected yearly variation of between 4 and 17 fatalities (inclusive) per year, in 19 out of 20 years. The number of fatalities for this year falls within this expected range and although low it is not statistically significant. The rate of accidental carbon monoxide fatalities has similarly decreased since 2001/2 to around 0.2 fatalities per million people at risk per year. This year, it was under half that value and remains well below 1 fatality per million people at risk per year which the HSE tends to take as the maximum figure for a broadly acceptable societal level of risk. 9 The trend in the yearly number of incidents (fatal or non-fatal) has declined considerably since 1997 from just under 100 per year. The minimum number reached was 18 incidents per year for 2005/6. There was, however, a noticeable increase during the subsequent three years followed by 57 and 56 incidents reported during 2008/9 and 2009/10 respectively. Discounting the current year (2009/10), the average since 2001/2 has been 37 incidents per year. If incidents were distributed with a Poisson distribution of mean 37 per year, a reasonable assumption for independent event data like accidents, the expected yearly variation due to chance alone would be between 24 and 50 (inclusive) in 19 out of 20 years. 10 The current count of 56 reported incidents, like the 57 last year, is outside this range and so it is concluded that this is not part of the normal yearly variation. It may well be that a contributory reason for the similar numbers of incidents reported this year and last year has been a consequence of the particularly cold winters. From Figure 7 it is evident that there are only minor differences between the age profiles of non-fatalities. Indeed, a statistical Chi-squared test shows that the reported distribution is not significantly different to that which would be expected by chance alone from the age distribution of the general population. However, this is an unreliable conclusion, as 27 casualties out of the 115 were of unknown age. The four fatalities were too few to analyse meaningfully by age groups. 8 The Met Office, Ref 12. 9 Paragraph 130, Ref 15 10 Poisson Cumulative distribution function Table, page 30 Ref 4 Gas Safety Trust Carbon Monoxide Incident Report 2010 13
2.4 Incident Location Details Section 3 of DIDR This section examines whether the risk of an incident varies with occupancy type; dwelling type, year of construction, double glazing and floor construction. 2.4.1 Housing tenure A breakdown of English homes with a boiler in 2008/9 by occupancy type is shown in Table 4. This is considered to be a reasonable measure of the breakdown of gas homes in Great Britain because a) although the number of homes with boilers will include LP gas and oil boilers it excludes a similar number without gas central heating and b) England accounts for 85% of the homes in GB. Table 4: Properties with a boiler by occupancy type (England 2008/9) 11 Occupancy type % of homes with a boiler Owner occupied 70.1% Rented privately 13.2% Rented from council 8.6% Registered Social Landlords (RSL) 8.1% ALL 100% Figure 8 shows the number of reported and expected incidents by occupancy type. The expected number is the national proportion by dwelling type (Table 5) multiplied by the total number of reported incidents of known occupancy type. Figure 8: Incidents by occupancy type 35 30 28 30 reported number of incidents expected number of incidents 25 Incidents 20 15 10 5 0 10 Owner occupied Rented privately Rented from council 5.7 4 Occupancy type 3.7 3.5 1 Rented RSL 13 Not stated 11 EHS Table 6, Ref 7. Gas Safety Trust Carbon Monoxide Incident Report 2010 14
2.4.2 Dwelling Type Column A of Table 6 shows the percentage of properties in England by dwelling type. Column B shows that in England 84.3% of detached homes, for example, had gas as the main heating fuel. The final column shows the percentage of gas properties in England by dwelling type. Figure 9 provides a breakdown of incidents by dwelling type and the expected number based on the national profile, were an incident in one particular type of dwelling to be equally as likely as in another type. The reported numbers of incidents by dwelling type were similar to the proportion of properties supplied with gas by dwelling type (Figure 9) for terraced houses, flats and bungalows but not for detached and semi detached houses. Table 5: English dwelling makeup by built form % of gas and non-gas properties by type in England 12 % of properties in England 13 that have gas the main heating fuel % of gas properties by type in England Column A Column B A x B Total(A x B) Detached house 17.4% 84.3% 17.3% Semi detached house 26.0% 90.7% 27.8% Terraced housed 28.6% 91.7% 30.9% Bungalow 9.4% 80.9% 9.0% Flats purpose built 14.9% 67.5% 11.9% Flats converted 3.7% 71.6% 3.1% Total 100% 100% Note: Total (A x B ) = [A (det) x B (det) ] + [A (semi) x B (semi) ]+...+ [A (conv. flat) x B (conv. flat) ] Figure 9: Incidents by dwelling type Incidents 20 18 16 14 12 10 8 6 4 2 0 Reported number of incidents Expected number of incidents 18 15 13 12 11.4 7.1 6.2 5 3 3 3.7 0 Detached Semi Terraced Bungalow Flats Not stated 12 Table SST6.1, EHCS Ref 6 13 Table SST6.1, EHCS Ref 6 Gas Safety Trust Carbon Monoxide Incident Report 2010 15
2.4.3 Property Construction Period Table 6 gives the estimated national breakdown of properties in each of five age range periods for property types on the DIDR form. Figure 10 shows the reported number and expected number (assuming all ranges pose equal risk) of incidents by property age range, based on the estimated national profile of the five age ranges specified on the DIDR form. Table 6: Estimated national breakdown by property construction period % of English gas and non-gas properties by built era 14 % of English properties that have gas as the main heating fuel 15 % of gas properties by built era in England Built era Column A Column B A x B Total(A x B) 16 Pre 1946 37.8% 86.8% 37.9% 1945 to 1965 19.6% 89.3% 20.5% 1966 to 1980 21.6% 84.5% 21.4% 1981 to 1990 8.8% 78.9% 8.1% Post 1991 12.2% 84.9% 12.1% Total 100% 100% Figure 10: Incidents by property construction period Incidents 18 16 14 12 10 8 6 4 2 0 Reported incidents Expected incidents 16 15 13 12 9 8.4 8.8 7 5.0 3.3 0 Pre 1946 1946 to 1965 1966 to 1980 1981-1991 Post 1991 Not stated Year dwelling built 14 EHS, Ref 7 15 Table SST6.1, EHCS Ref 6 16 See Table 5 note. Gas Safety Trust Carbon Monoxide Incident Report 2010 16
2.4.4 Glazing type The breakdown of glazing type in England is 16.4% single-glazed, 13.0% mixed single- and double-glazed and 70.6% double-glazed. 17 Figure 11 compares the number of reported incidents with those expected from the national figures for glazing categories. It should be noted that it was not possible to obtain exact estimates of the relative proportions of single and mixed glazing. Instead those properties with partial double glazing were considered in the category 50% to 99% partially double glazed and those with single glazing were equated to less than 50%. The number of properties nationally which are fully double glazed is a reliable estimate. In 2009/10, there were more carbon monoxide incidents reported than would be expected for entirely double glazed properties but this was not statistically significant. Figure 11: Incidents by glazing details 34 Reported number of incidents 28 Expected number of incidents 16 4 6.5 2 5.2 Single Partial Double Double Not stated Glazing type 2.4.5 Floor type Table 7 shows the incidents reported broken down by ground floor construction type. Table 7: Incidents by floor construction Ground floor construction Reported number of incidents Solid 24 Suspended 5 Partial solid 4 Not stated 23 Total 56 17 EHS 2008: Table 7 Ref 7 Gas Safety Trust Carbon Monoxide Incident Report 2010 17
2.4.6 Discussion In Figure 8, the only substantial difference between the number of carbon monoxide incidents reported compared with those expected is for those homes rented privately: 10 were reported whilst only 6 would be expected based on the national profile. A binomial statistical test assuming privately rented households are equally at risk to those that are not privately rented, reveals the probability of 10 or more incidents occurring by chance alone in privately rented accommodation is 0.05. However, this is not statistically significant. In order for the difference in risk for those renting privately compared to those in other tenures to be statistically significant, the probability needs to be 0.025 or less. A Chi-square test was carried out to test 18 the hypothesis that households in each dwelling type are equally at risk. No statistically evidence was found to reject the hypothesis and so it is concluded that there is no noticeable increase in risk associated with dwelling type. The data presented in Figure 10 shows that proportionately, a dissimilar number of incidents were reported in older properties compared to newer properties. Using a Chi-square test this is, however, not statistically significant. It is concluded that the risk of an incident during 2009/10 was not significantly influenced by property age. National statistics on floor construction are not readily available. However, an estimate in England based on property age is that 30% have suspended floor construction. 19 A similar estimate made assuming all properties with cavity walls have solid floors also produces the same result of 70% with solid floors (18.0 million in 25.6 million in 2008 20 ). If this were the case and each floor type posed a similar risk of an incident, the expected number of incidents in properties with a suspended floor construction would be 9 and for solid floor would be 22. In fact, there were 5 and 24 reported respectively, but these figures are not significantly different. Therefore, the type of floor construction is not considered to have a bearing on the likelihood of a carbon monoxide incident taking place. 2.5 Casualty & Appliance Location Section 4 of DIDR The section covers the reported location (eg room or compartment) of both the incident appliance and those injured. No reports implicated more than one appliance. Details of all the incident appliance locations, by floor level, are given in Table 8. Table 8: Incident appliance location by floor level Floor on which the appliance was situated Number of incident appliances Roof space 0 Higher than fourth 1 Fourth 0 Third 0 Second 0 First 5 Ground 35 Below ground 1 Not stated 14 18 The category of bungalow and flats had to be merged for the test to be valid. 19 This assumes dwellings built before 1929 are suspended floors and those after are solid floor, which is reasonable for England and Wales. Scotland has different historic practices. 20 Table 3. EHS Ref 7 Gas Safety Trust Carbon Monoxide Incident Report 2010 18
Table 9 lists where the incident appliances were reported to have been located together with the numbers of casualties at each location. The most common location for an incident appliance was the kitchen followed by the living rooms and hall/landing. Table 9: Appliance and casualty locations Number of appliances at each location Number of casualties at each location Number affected where the occupants were in the same room as the appliance Fatal Non-fatal Hall/landing 4 1 0 0 Kitchen 19 8 0 0 Living rooms 13 17 0 8 Bathroom 1 2 0 0 Utility 1 0 0 0 Bedroom 0 18 0 0 Other 1 0 0 0 Not stated 17 69 The most common location for casualties was the bedroom, followed by living rooms, kitchen and bathroom. A further breakdown concerned the number of incident appliances fitted in compartments. There were 11 incidents reported that involved appliances in compartments, out of a total 34 where the relevant details were recorded. This is presented in Figure 12. Figure 12: Incident appliances installed in compartments 25 20 23 22 15 10 11 5 0 Room Compartment Not stated Of the 32 reports that provided a response to the question whether the casualty was located in the same or an adjacent property, 31 reported that they were located within the same property as the incident appliance. The exception was an installation that injured four people next door and the incident was caused by bad siting of a flue terminal at a terraced property. 2.5.1 Discussion Without data on the nationwide breakdown of appliance installations by room, it is not possible to judge the significance, if any, of the incident appliance location. The location of casualties reported during the year was not surprising given people tend to spend most time in the bedroom followed by the living room and kitchen and indeed may go to bed if they feel unwell (as may be the case when suffering symptoms of carbon monoxide poisoning). Gas Safety Trust Carbon Monoxide Incident Report 2010 19
No fatalities were reported to have occurred in the same room as the suspected appliance, although room details were only provided for two of the four fatalities. 8 of the 36 non-fatalities were reported to have the appliance and casualty located in the same room. This number may be small because the occupants might not immediately feel unwell following exposure to carbon monoxide and therefore, when symptoms do appear they may have moved to a different room. Alternatively, exposure may be a result of carbon monoxide migrating around the property. Without the knowledge of how many appliances are installed in compartments nationwide, it is not possible to gauge the significance or otherwise of whether compartment mounted installations are more at risk of being involved in an incident. Last year a similar proportion of the detailed incident reports involved appliances in compartments (12 out of 35). Installing appliances in compartments can in some circumstances exacerbate the way in which carbon monoxide is produced and spreads around a property following appliance/installation malfunction. The single incident which led to 4 casualties in an adjacent property is not an isolated instance involving injury outside the property where an appliance/installation has malfunctioned. There have been other occasional incidents recorded on the carbon monoxide incident database that involved casualties in adjacent properties as a result of appliances/installations malfunctioning in adjacent semi-detached properties, terraced properties and flats. 2.6 Incident Appliance Details - Section 5 of DIDR This section examines appliance details to see if there are any factors that could help influence future installation and maintenance guidance. 2.6.1 Appliance type Details of incidents classified by the appliance type involved are given in Figure 13. Figure 13: Incidents by appliance type Not stated 11 Cooker/boilers Tumble dryers Water heaters Space heaters 6 Cookers 5 Central heating 34 5 10 15 20 25 30 35 40 Number of incident appliances Most incidents where the appliance type was specified (34 out of 45) involved central heating appliances, two of which were warm air heaters. This is as expected given the prevalence of central heating installations, their larger heat output and the fact that they tend to be in operation for a significant length of time. There were five incidents involving cookers. Gas Safety Trust Carbon Monoxide Incident Report 2010 20
2.6.2 Central heating and boiler type The incident numbers involving a specific type of central heating appliance are further broken down in Figure 14. One incident resulting in two casualties involved a central heating appliance of unspecified type and is not shown. Figure 14: Incidents by central heating type 34 Incidents Fatalities Non-fatalities 16 15 15 11 6 3 5 1 2 4 2 2 Back boiler unit Regular Boiler Combi boiler Thermal storage unit Regular condensing Combi condensing Warm air unit In order to establish the relative risk presented by each boiler type, Table 10 projects forward the boiler population by type. It does this by using population figures from September 2008 and projects these forward to the middle of the current reporting period using annual boiler sales in England of 1.6 million 21 apportioned 2:1 between condensing combi boilers and condensing regular boilers. When calculating the relative risk value the important figures are the percentage breakdown by type. Such a percentage breakdown for England has been assumed to apply to GB as a whole. It is worth noting that by December 2009 over a quarter of boilers installed were of the condensing type due to energy efficiency legislation introduced in April 2005. In 2001 only 2% of boilers operating in the home were condensing, in 2005 this was 5% and today it is estimated to be 25%. 22 Table 10: Projected boiler populations by type (England, Dec 2009) September 2008 Number Sold from Sep December 2009 % of all dwellings by type boiler Number, 000s 2008 to Dec 2009, millions Number, 000s % of dwellings with boilers Data Source: 23 English housing survey 2008/9 Heating and Hot Water Industry Council 24 Projected forward Boiler type Regular 41.3% 8072 7517 38.4% Back boiler 8.6% 1688 1688 8.6% Combi 31.1% 6082 4955 25.3% Condensing-regular 4.8% 948 555 1503 7.7% Condensing-combi 14.2% 2773 1127 3900 19.9% 21 1.9 million sales in the UK (HHIC Ref 14) x 22.2 dwellings in England / 25.2 households in GB, Social Trends Survey Ref 5 22 Table 3.9 Energy Consumption in the UK, Domestic data tables, 2010 Update 23 EHS Ref 7. 24 Market Updates 2008 Q2 to 2010 Q1 Ref 14. Gas Safety Trust Carbon Monoxide Incident Report 2010 21
Figure 15: Reported and expected incident numbers by boiler type 15 11.9 Reported number of incidents Expected number of incidents 7.9 6 2.7 5 1 2.4 4 6.2 Regular Back boiler Combi Condensing-regular Condensing-combi Figure 15 compares the 31 carbon monoxide incidents reported with a known boiler type with those expected given the prevalence of each boiler type in the general population and assuming each poses equal risk. The expected number is the total number of incidents reported with a known boiler type multiplied by the percentage breakdown of boiler types in the general population. There are higher than expected numbers of regular (noncondensing) and back boiler units and fewer than expected of the newer types (condensing models and combi models). The expected numbers in at least 20% of the categories are too few (less than five) to a carry out a Chisquare test, to determine whether this statistical significant or not. However, it is only possible to test the significance of incident rates (and hence risk) by having expected values of 5 or more. To achieve this, it was necessary to combine the categories of regular with back boilers and combine the categories of condensing combi with condensing regular boilers. A Chi-squared test revealed with 99% confidence that back boilers and regular (non-condensing) boilers posed a greater risk than combi (non-condensing) boilers, which in turn posed a higher risk than condensing boilers. 2.6.2.1 Condensing boilers For the third year running, there are some reported incidents involving condensing boilers (all room sealed). This is considered to be a reflection of the rapid increase in the condensing boiler market (now over 99% of sales and a quarter of the general boiler population in 2009) due to energy efficiency legislation introduced in April 2005. If an incident involving a condensing boiler and a non-condensing boiler were equally likely it would be expected, based on the estimated condensing boiler population, that between 3 and 13 (inclusive) out of 33 incidents would involve condensing boilers in 19 out of 20 years. The number reported is 5 which falls within this range. Therefore the risk associated with a condensing boiler is not statistically different to that associated with non-condensing boilers. 2.6.2.2 Boiler age Figure 16 shows the reported and expected incident numbers for the boilers of known age. The expected number is based on the age profile from the 2006/7 annual incident report which will be an approximation for the December 2009 age profile. 25 It assumes the age profile has not changed significantly over 4 years. The reported number is nearly ten times higher than expected number for boilers older than 20 years, slightly higher for 11 to 20 years old boiler and considerable lower for boiler 10 years old or less. 25 Appendix E, Ref 1 Gas Safety Trust Carbon Monoxide Incident Report 2010 22
Figure 16: Incidents by boiler age Reported number of incidents Expected number of incidents 11 8.6 5.4 2 1 3 3 1.9 2.7 1.3 age < 6 years 6 to 10 years 11 to 15 years 16 to 20 years age > 20 years Expected numbers are too few in 20% of the groups to determine statistical significance using the Chi-squared test across all boiler age groups. However, a binomial test can judge the significance of incidents with boilers greater than 20 years old compared to the incidents with newer boilers. Assuming a boiler over 20 years old poses the same risk as a boiler under 20 years; then the chance of 11 or more incidents out of 20 occurring by chance alone is very small; less than 0.001. Expressed another way, in 19 out of 20 years, if the risk were independent of age then out of the 20 boilers with a known age, zero to three incidents would be expected for boilers older than twenty years where as 11 were reported. It is therefore concluded that boilers over 20 years old pose more of a risk than boilers less than 20 years old. A similar argument applies to boilers 10 years old or newer compared to boilers over 20 years old but here the newer boilers pose less risk. Table 11 summarises the expected risk compared to a boiler 10 years old or less. Table 11: Relative risk by boiler age (base case 10 years old or less) Boiler age 95% confidence lower limit mean 95% confidence lower limit 11 to 20 years 1.3 1.5 1.8 Older than 20 years 18.8 19.5 20 Table 11 shows that a boiler over 20 years old has an associated risk of a carbon monoxide incident 20 times that associated with a newer boiler (10 years or newer) and that the risk associated with a middle aged boiler is 50% more. The above analysis assumes the reported age data for boilers of unknown age is distributed in the same way as boilers of known age. The age of older boilers is harder to determine by the investigator so that a greater proportion of those boilers whose age is reported to be unknown is more likely to be older than that assumed by the known incident age distribution. This means an under reporting of older boiler age and therefore the risk values calculated above are considered to be conservative estimates. Gas Safety Trust Carbon Monoxide Incident Report 2010 23
2.6.3 Trends in incident rates Table 12: Incident numbers by appliance age Appliance Type Age (years) 0-5 6 10 11-15 16-20 Over 20 Unknown Cooker 0 1 0 1 0 3 Other 0 0 0 0 0 0 Space Heater 2 1 0 0 0 3 Central Heating 2 1 3 3 11 14 Water Heater 0 0 0 0 0 0 Total 0 1 0 1 0 3 Table 12 lists the numbers of incidents reported this year and breaks these down into appliance type and appliance age. Figure 17 shows the yearly fatality numbers associated with appliance type since July 1996. Figure 17: Fatalities by appliance type Number of fatalities 30 25 20 15 10 Unknown Other Water Heaters Space heaters Cookers Central heating 5 0 96/97 97/98 98/99 99/00 00/01 01/02 02/03 03/04 04/05 05/06 06/07 07/08 08/09 09/10 July to June 12 month period 2.6.4 Absolute risk of a carbon monoxide incident by appliance type This quantifies the overall risk associated with appliance type to determine whether it falls within generally accepted safety guidelines. It requires a reliable estimate of the appliance population nationwide. Such appliance population estimates are only available for boilers and cookers and therefore absolute risks have only been calculated for these categories of appliance type. Gas Safety Trust Carbon Monoxide Incident Report 2010 24
2.6.4.1 Absolute risk of a carbon monoxide incident involving boilers For 2009/10, the estimated number of gas households with central heating in Great Britain was 20.5 million. 26 Using 20.5 million as the number of homes with gas central heating (corresponding to 48.8 million people), an estimate of the range of the incident rates related to gas boilers can be derived (see Table 13). The higher estimate of risk assumes all unknown appliances were boilers and the lower estimate assumes none of these were boilers. Table 13: Incident data for central heating boilers July 1st 2009 to June 30th 2010 Incidents Fatalities Non-fatalities Carbon monoxide related incidents including 11 incidents with unknown appliances which had no fatalities and 20 non-fatalities) 45 3 102 Carbon monoxide related incidents excluding unknowns 34 3 82 Rate per million people per year (assuming unknowns are not central heating boiler related) 0.70 0.06 1.68 Rate per million people per year (assuming unknowns are central heating boiler related) 0.92 0.06 2.09 The risk of a fatality is less than the commonly accepted health and safety criterion of 1 fatality per million people at risk per year and is also less than a tighter risk constraint of 1 fatality per 10 million people at risk per year (the latter equates to 5 fatalities nationwide per year). 2.6.4.2 Absolute risk of a carbon monoxide incident involving cookers The estimated gas hob and gas oven populations for GB are shown in Table 14. Table 14: UK cooking appliance population estimates Source data DUKES 27 Inferred populations Electric ovens millions Electric hobs millions Households millions Gas hobs and ovens millions Electric hobs and ovens millions Gas hobs and electric ovens millions UK households 16.6 12 26.6 10.0 12.0 4.6 GB households 25.3 28 9.5 11.4 4.4 GB population 22.6 27.2 10.4 Table 14 assumes: 1) Homes without an electric oven have a gas hob and oven 2) Home with an electric oven have an electric hob. 3) Percentage ownership of cooking appliances is the same in the UK as in GB. The estimated risks associated with cookers assuming the above populations are shown in Table 15. A range of risk is shown because of the differing assumptions made about the incident data concerning unknown appliances. 26 81% x 25.3m; (25.3 million households in GB 2009 table 2.1 Social Trends Survey, Ref 5 of which 81% have gas central heating; 85.7% have gas and 4.7% have no central heating in England EHCS; Ref 6) 27 Table 3.11, EST Ref 10. 28 Table 2.1, Social Trends. Survey, Ref 5, project forward six months. Gas Safety Trust Carbon Monoxide Incident Report 2010 25
Table 15: Incident data for cookers July 1st 2009 to June 30th 2010 Incidents Fatalities Non-fatalities Any gas cooking appliance incidents Carbon monoxide related incidents including 11 incidents with unknown appliances which had no fatalities and 20 non-fatalities 17 0 27 Carbon monoxide related incidents excluding unknown 6 0 7 Any gas cooking population appliance base Rate per million people per year (assuming unknowns are not cooking related) 0.18 0 0.21 Rate per million people per year (assuming unknowns are cooking related) 0.51 0 0.82 Gas hob and oven Rate per million people per year (assuming unknowns are not cooking related) 0.27 0 0.67 Rate per million people per year (assuming unknowns are cooking related) 0.75 0 2.59 Fatality rates for cookers this year were zero and in marked contrast to last year when seven fatalities occurred. Incident rates were lower for cooker than boilers. 2.6.5 Discussion This year, the figures show that older boilers are more likely to be involved in an incident. This serves to highlight the importance of servicing such appliances as per manufacturer s instructions. Such servicing would provide the opportunity to confirm the appliance would remain in an acceptable condition until the next service was due. It should also be remembered that older appliances tend to have older flue systems associated with them and a service visit should not focus exclusively on the appliance but also on the flue system to ensure the complete installation remains safe. Many older appliances are capable of remaining in safe operation but the servicing interval should be respected to help ensure this continues. Data relating to boiler type continues to show that regular (non-condensing) boilers and back boilers pose a greater risk of being involved in an incident than condensing boilers. This trend is likely to continue given the way legislation only allows new or replacement condensing boilers to be installed. Gas Safety Trust Carbon Monoxide Incident Report 2010 26
2.7 Details relating to individual appliance types and models Detailed information about the incident appliances are given as it was stated on the DIDR form. This included the manufacturer s name and model which has been included for the record. No significance can be attributed to models or manufacturers without relating this to the numbers of such appliances installed nationwide. For example, the most frequently occurring manufacturer s name featured in the incident reports may be there simply because it is the most common manufacturer in the general population or, alternatively, that the incident may have had nothing to do with the design/performance of the appliance, but a consequence of poor installation practice. 2.7.1 Fatal incidents 2.7.1.1 Boilers Three fatalities were linked to boilers. All three were single incidents and outline details are listed below for different boiler types. Back boiler units (BBU) No fatal incidents Floor mounted regular boiler No fatal incidents Wall mounted non-condensing regular boiler Three incidents each involving one fatality Worcester 240 installation and ventilation fault (included three casualties) Glow-worm, Fuel saver, 30B Occupant interfered with appliance causing towels to obstruct the air intake. Glow-worm, Fuel Saver, 23/50 Flue installation; ventilation and lack of servicing (also included one casualty). Wall mounted condensing combi boiler No fatal incidents Wall mounted condensing regular boiler No fatal incidents 2.7.1.2 Space heaters One fatality involved a space heater. Details were not provided but it was a DIY installation of a fire purchased on the open market. 2.7.1.3 Cooking appliances No fatalities were linked to cooking appliances 2.7.2 Non-fatal incidents The following sub-sections describe those appliances involved in non fatal incidents that were fully investigated. Gas Safety Trust Carbon Monoxide Incident Report 2010 27
2.7.2.1 Boilers Boilers were involved in 31 incidents. One incident where boiler details were not reported. Back boiler units (BBU) Baxi Bermuda fire C4 / Boiler 45/3 no cause found/stated Glow-worm Capricorn 240 6 incorrectly lit by occupant Baxi Bermuda 552 B lack of servicing and ventilation fault Baxi Bermuda 552 back boiler with glass front lack of servicing Glow-worm 56/3 with Melody 3 Fire Front 56/3 lack of servicing and ventilation fault Baxi Bermuda 552 lack of servicing Wall mounted condensing regular boiler Ideal Classic FF350 installation fault Wall mounted condensing combi boiler Coopra Advanced Technologies BV Eco EC25HJ flue separated from boiler due to sub-standard servicing Ideal ISAR 24 HE appliance fault Vokera Syntesi 25e poor servicing Worcester Greenstar 12 rsi unknown/not yet established Combi-boilers non-condensing Ideal Mexico 2 flue/terminal fault Myson Apollo 30C poor servicing Ideal Eden WCF 30 - poor servicing Worcester 240 OF flue/terminal fault Valliant VCW 20/1 T3 appliance, ventilation, flue/terminal fault Regular boilers non-condensing Ideal Mexico Super CF100 flue/terminal, installation, ventilation fault and lack of servicing Potterton Kingfisher 2 CF50 flue/terminal, installation, ventilation fault and lack of servicing and sub- standard compartment Ideal Mexico Super CF50 flue/terminal fault Ideal Vulcan Continental lack of servicing Ideal Concorde WCF 255 cause not established Ideal Classic RS250 poor servicing Baxi 70/4 PF leakage near fan Glow-worm Fuel Saver Mk II lack of servicing Myson Apollo lack of servicing Glow worm 75 MKII flue/terminal fault Wickes 45/60 installation fault Ideal Concord WRS 240B appliance misuse (outer casing removed) Gas Safety Trust Carbon Monoxide Incident Report 2010 28
2.7.2.2 Warm air heaters Two incidents involved warm air heaters. Johnson and Starley JT 19-25 appliance fault, ventilation and installation fault, poor servicing and sub- standard compartment. Johnson and Starley lack of servicing and ventilation fault 2.7.2.3 Space heaters Three incidents involved space heaters. One incident with details of space heater not reported Decorative fire Taylor Portway Ltd EAC 18 NGR flue terminal Fault New World Power Flame no cause established Flavel Emberglow flue installation fault Inset live fuel effect Adam Radiant fire flue/terminal fault; coals misplaced Focal Point, Lulworth appliance fault, installation, flue/terminal fault 2.7.2.4 Cooker/boiler No incidents 2.7.2.5 Cookers Five incidents involved cookers. Details were not supplied for two. Stoves Cooker damaged and lack of servicing Main Maestro appliance fault, lack of servicing Cannon burner incorrectly fitted Gas Safety Trust Carbon Monoxide Incident Report 2010 29
2.8 Appliance Installation Details Section 6 of DIDR Table 16 provides information relating to the person reported to have installed the appliance involved in an incident and whether the appliance installation had been to standard. Table 16: Appliance installation details Installer details To current standards To standards current at time of installation Not to any appropriate standards Unsure / don t know Registered 4 3 1 1 9 Non-registered 0 0 1 0 1 DIY 0 0 1 1 2 Unknown 5 8 9 22 44 Total 9 11 12 24 56 Total The vast majority of appliances had unknown installers (44 out 56) so a comprehensive review of those carrying out incident appliance installation could not be obtained. One registered operative carried out an installation that was not to standard. This was a boiler installed around 1992 and it was reported as having both inadequate room ventilation and compartment ventilation. Three appliances were installed by non-registered operatives of which two were not installed to standard. The third appliance was assumed to have not been standard as the incident was reported to have been the consequence of the occupant installing a gas fire himself. This resulted in his death. The reasons given for the other two incidents being reported as having been sub-standard appliance installations were: Incident 1 a gas pipe was not sleeved and a compression fitting was located in a chimney void on one installation. Incident 2 a flue was installed through a wall into an enclosed area and the gap in the flue duct in the other installation allowed products of combustion to escape. Two incidents were reported to have followed DIY installations. One of these involved a second-hand gas fire and resulted in the installer s death. The other installation resulted in six people requiring medical treatment. A further incident involved an installation carried out by a non-registered operative and occurred in a privately rented property. This involved a second hand gas fire which had been installed in 2009. 2.9 Flue Details Section 7 of DIDR A breakdown of 45 (out of the 56) incidents by flue type involved is shown in Figure 18. As has been the case in previous years, incidents involving open flues were common (22) and in particular were associated with 2 out of the 4 fatalities reported. There were also 20 incidents reported that were related to room sealed appliances and these included one fatality. Gas Safety Trust Carbon Monoxide Incident Report 2010 30
Figure 18: Incidents by flue type Shared Individual Room Sealed, Natural Draught Room Sealed, Fanned Draught, Depressurised Room Sealed, Fanned Draught, Pressurised Open, Fanned Draught, Integral Open, Fanned Draught, Add On Open, Natural Draught Flueless (three cookers) Other Room Sealed, Shared Open, Shared, Natural Draught Open, Shared, Fanned Draught 1 13 5 1 Fatal Non-fatal 2 20 3 0 5 10 15 20 25 Incidents The number of domestic central heating boilers with open flues is reducing. During the recent scrappage scheme for boilers it was estimated there were 3.5 million G-rated boilers nationwide. 29 A DTI study 30 estimated that the open flued boiler population in May 2005 was 3.8 million with 16.5 million room sealed appliances. This remains the latest and best estimate available of boiler population by flue type although it is now some five years out of date. Since then the number of room sealed boilers will have increased as condensing boilers (all room sealed) are now over 99% of the annual UK sales and represent an estimated 25% of all boilers in domestic use in 2009. The estimate of the nationwide population of open flued boilers in 2009 has been based upon 2005 figures. This has therefore produced a conservative estimate for the relative risk associated with open flued boilers compared to room sealed boilers. Table 17 shows the boiler incidents reported where the flue status was specified (42) and the expected number based upon the estimated boiler population for May 2005. Table 17: Reported and expected incident numbers for boilers by flue type Boiler flue Reported number Expected number Open flue 22 4 Room sealed 20 16 Assuming open flued and room sealed appliances are equally likely to be involved in an incident, then the probability of 22 or more incidents occurring by chance is very small (less than 0.01%). It is therefore concluded that boilers with open flues expose occupants to a significantly higher risk of a carbon monoxide incident, fatal or not at least 4.6 times that of room sealed appliances. This is not unexpected given that boilers with open flues are intrinsically less safe because of the potential for spillage of combustion products directly into the room. Since 2005, the population of boilers with open flues will have declined considerably; the relative risk associated with open flue boilers compared with that posed by room sealed boilers is a conservative estimate of the risk in 2009/10, hence the words at least. 29 EST website, accessed 23/10/2010, Ref 13 30 page 64, Ref 9. Gas Safety Trust Carbon Monoxide Incident Report 2010 31
Figure 19: Incidents by flue standards 14 12 12 Non-fatal Fatal 10 Reported incidents 10 8 6 4 7 2 1 To current standards To standards current when installed 2 Not to standards 1 Unknown Flue installation status An analysis of the 32 incidents with known flue installation status indicated that nearly 40% had not been installed to standard (either current or existing at installation), which is a sizeable proportion. This compares with a corresponding proportion of 50% not installed to standard last year, so the issue is worthy of comment. Two fatal incidents were each linked to flues that had not been installed to any standard and one fatal incident was linked to a flue that had been installed to current standards. The latter was caused by the occupant inserting towels into the boiler casing which obstructed the air inlet to the appliance. 2.10 Permanent Ventilation Section 8 of DIDR About half of the completed DIDR forms (30 out of 56) specified whether permanent room ventilation was required or not. 27 out of the 30 reports stated the room ventilation requirement. The breakdown of DIDRs where it was stated that ventilation was required is summarised in Figure 20. When permanent ventilation was provided it was generally substandard. 20 incidents that indicated room ventilation was required had inadequate provision and these included two fatal incidents. Figure 20: Incidents by reported ventilation condition Unknown Fatal Non-fatal Permanent ventilation status when required None provided Not to standards To standards at time of installation 1 1 4 6 12 To current standards 5 2 4 6 8 10 12 14 Reported incidents Gas Safety Trust Carbon Monoxide Incident Report 2010 32
Where ventilation was provided, there were four incident sites at which this was found to be unobstructed. A breakdown of those incident sites where partially or totally obstructed vents were reported is given in Table 18. Table 18: Incidents reported with obstructed ventilation Number of incidents with: Vents intentionally obstructed 4 Vents unintentionally obstructed 3 2.11 Safety Devices Section 9 of DIDR The categories of safety device specified on the DIDR forms are carbon monoxide detectors (chemical spot or battery/mains powered alarm type), downdraught sensors and anti-vitiation devices. Safety devices were reported at 16 out of 19 sites where safety information had been completed on the DIDR form. Carbon monoxide detectors were found installed at 14 (25%) of the incident sites. 3 of the detectors were found not to be working. Of those detectors where the type was specified, 1 was a chemical spot detector and 7 were battery operated alarms. No details were provided for the remaining 6. Two of the carbon monoxide detectors were installed in the same room as the appliance and one in the same room as the affected occupant. 8 anti-vitiation devices and four downdraught sensors were also identified on incident appliances. 2.11.1 Discussion The figure of 25% for the percentage of incident sites where carbon monoxide detectors were found was higher than that reported last year. The average for reporting years 2005/6 to 2008/9 was 18% of sites and the average prior to 2005/6 was 5%. This reflects the increased use of such equipment and it is possible that this contributed to this year s recorded fall in the severity of injuries reported. There is further evidence that audible carbon monoxide alarms may be helping to reduce the number of potentially serious incidents. Five cases were brought to the attention of British Gas by the emergency service provider, which were not subsequently identified as meeting the RIDDOR reportable incident criteria because the occupants were alerted before any injury occurred. 2.12 On-site Checks Section 10 of DIDR The on site investigation of an incident involves the investigator making a number of fundamental observations and carrying out specific checks and measurements. The results of these are reported in Section 10 of the DIDR form and are broken down by category in Figure 21 and Table 19. There was a wide range of faults but it should be remembered that these have not necessarily caused the incident. The specific faults which were considered to have contributed to each incident are discussed in Section 2.14. Gas Safety Trust Carbon Monoxide Incident Report 2010 33
Figure 21: Reported faults by type 50 Number of faults reported 45 40 35 30 25 20 15 10 5 30 21 15 7 37 14 40 41 Burner problems Heat exchanger problems Flueing faults Safety device faults Appliance performance Terminal faults Ventilation faults Miscellaneous Table 19: Incident appliance faults Fault group Number of faults Fault group Number of faults Burner Appliance performance Corrosion 2 High CO/CO 2 ratio 19 Defective flame picture 8 Failed spillage test 11 Linting 8 Overrated 4 Over-pressure 5 Underrated 3 Under-pressure 2 Terminal Other 5 Down draught 3 Flue Bad siting 8 Blockage 5 Unapproved design 0 Corrosion 1 Other 3 Flue not to any standard 0 Ventilation Installation fault 14 Air vent/vents ineffective 7 Other 1 Air vents obstructed intentionally 4 Heat exchanger Air vents obstructed unintentionally 3 Blockage shale 2 Compartment not to any standards 6 Blockage soot 8 No permanent ventilation provided 7 Cracked 2 Ventilation was not to any standard 13 Other 3 Miscellaneous Safety device Local topography 3 Carbon monoxide inoperable alarm 3 Weather 15 Failed downdraught sensor 1 Signs of spillage outside the appliance 10 Failed vitiation device 3 Signs of spillage inside the casing 13 Note to Table 19 The numbers quoted are the numbers of appliances found with the fault listed. Carbon monoxide alarm could be inoperable as it had no battery or did not function when tested using either a portable carbon monoxide kit or was tested off site. Gas Safety Trust Carbon Monoxide Incident Report 2010 34
2.13 Incident Appliance History Sections 11 and 12 of DIDR Service history details were reported for 44 incidents and details are given in Table 20. This represented a much improved completion rate compared to last year. One fatality involved an appliance on which there was no service contract. For the other three fatalities, service contract information was either not reported or unknown. Table 20: Details of service history Service history status Number of incidents Number of fatalities Number of non-fatalities On a regular service contract 15 0 30 Not on a regular service contract 19 1 38 Unknown if on a regular service contract 10 2 26 Total where the service history was known (sum of three rows above) 44 3 94 Total reported incidents 56 4 115 NB One of the 45 fully reported incidents did not feature service history details (see Section 1.3) The registration status of the gas operative who attended the installation prior to the incident is given in Table 21. A working visit is a visit other than the original installation. Table 21: Details of last working visit Number reported Number of fatalities Number of non-fatalities Non-registered operative 2 0 8 Registered operative 23 1 48 Unknown 19 2 38 Working visited reported 44 3 94 Total for reported incidents 56 4 115 NB One of the 45 fully reported incidents did not feature service history details (see Section 1.3) One fatal incident report specified the last working visit had been by a registered operative who was called to service the boiler. The reported causes of the incident were a flue/terminal and a ventilation fault combined with unusual weather conditions. Concerns appear to have been raised during the last recorded visit, three months prior to the incident, as a warning notice was found tied to a temporary water filling loop. About half (23 out of 44) of the incidents reported the last working visit had been by a registered operative. An analysis of the time period that elapsed between the last working visit and the incident is given in Table 22. Just over half of the properties were reported as having a working visit within a year of the incident. Two of the fatal incidents reported involved an operative making a working visit to the property less than 6 months prior to the incident. At one of these properties a warning notice had been left by the operative but the category of risk was not specified by the investigator on the DIDR report. Gas Safety Trust Carbon Monoxide Incident Report 2010 35
The other fatal incident involved a faulty flue installation and on this occasion an ID warning notice had been placed on the boiler 4 months prior to the incident. It is not known whether the operative had disconnected the appliance from the gas supply or the occupier had re-connected it. Warning notices are classified as immediately dangerous (ID), at risk (AR) and not to current standards (NCS). 31 Out of all the incidents reported this year, warning notices had been left at four premises prior to the incident occurring. Two of these were fatal incidents and two were non-fatal. Those notices involving the non-fatal incidents had been left 6 months and 26 months prior to the incident occurring. These incidents had the causes reported as a ventilation fault (the ventilation grille was above and too close to the boiler) and a flue installation fault respectively. It would appear the occupier had failed to act upon the warning notice. Table 22: Interval between the last working visit and the incident Time between the last working visit and the incident Number of reported visits Number of reported fatalities Number of reported non fatalities Less than 6 months 20 2 39 6 months to 1 year 4 0 12 1 year to 2 years 3 0 7 More than 2 years 6 0 10 Unknown 8 1 13 Total with appliance history 41 3 81 Total of all reported incidents 56 4 115 NB 4 of the 45 fully reported incidents did not feature appliance history details (see Section 1.3) 2.13.1 Discussion It would be expected that registered operatives visiting in the 12 months prior to an incident (24 reported during 2009/10) would be checking to ensure that an appliance would work satisfactorily for at least the next twelve months. If all due care was taken, only on rare occasions would an appliance be expected to fail and this would typically be due to misuse or particularly extreme adverse weather conditions. It would be reasonable to expect that most appliances would be safe for a year after a working visit by an operative but this appears not to have been the case as nearly half (23) of the incidents had a registered operative visit within the twelve months prior to an incident. In addition, the four incidents reported this year where warning notices had been issued brings into question the effectiveness of the warning notice classification system covered by the Gas Industry Unsafe Situations Procedure. 31 The Gas Industry Unsafe Situations Procedure, Ref 11 Gas Safety Trust Carbon Monoxide Incident Report 2010 36
2.14 Incident Cause/Causes - Section 13 of DIDR Details of the cause or causes of reported incidents are summarised in Figures 22 and 23. It should be noted that these causes are different from the general faults discussed in Section 2.12. Figure 22 shows the distribution by the number of causes reported per incident. For example, a single cause was recorded for 30 incidents whilst a further 8 had 2 causes specified. Zero causes means there had been no cause specified or one had yet to be established. Experience has shown that incidents tend to occur when a number of events conspire to produce carbon monoxide and lead to its discharge into a property. This year, a sizeable number of incidents were reported as having a single cause (30 out of 56). Figure 22: Distribution of the number of stated causes 35 30 30 Frequency 25 20 15 10 5 0 8 9 6 2 1 0 1 2 3 4 5 6 7 8 Number of identified causes per incident In Figure 23 the counts have been standardised by dividing the counts by the number of established causes per incident and are expressed as a percentage of the total count (56). For example, if there were three causes stated for one incident, each of the three causes would be allocated a third of a count. Figure 23: Reported causes 30% 25% 24% Standarised count 20% 15% 10% 15% 11% 7% 16% 8% 6% 11% 5% 1% 1% Appliance fault Appliance installation fault Customer misuse Flue / terminal fault Lack of servicing Sub-standard compartment Sub-standard servicing Ventilation fault Not known Weather Gas Safety Trust Carbon Monoxide Incident Report 2010 37
The blocking of vents is discussed in Section 2.10. Weather, as a reported cause, is usually associated with high winds but could also mean low temperatures. If all causes were equally likely, the contribution score for each cause group would be 10%, so groups with a contribution score above 10% constitute a higher contribution than average. Lack of servicing was the most common cause specified by investigators with an equivalent sole cause specified in a quarter of the incidents (24%), followed by flue/terminal fault (16%), an appliance fault (15%), an appliance installation fault (11%) and unknown cause (11%). This year, appliance faults included faulty gas valves, appliance installation faults were usually associated with the boiler flue connection and flue/terminal faults typically comprised the incorrect positioning of the flue termination (eg a flue terminal placed below and/or too close to an air inlet grille). Reports of customer misuse of an appliance as the cause of an incident were down compared with last year from 13% to 7%. Customer misuse was relatively high last year because cookers had been used as heaters and left on too long. There were also instances where the grill had been used with the door to the grilling section closed. This year misuse of cookers as heating appliances did not result in any fatalities, in spite of the winter being colder than last year and the coldest since 1978/9. One non-fatal incident was the result of using a damaged cooker. The cooker had been damaged when it had somehow fallen over prior to the incident occurring. Three incidents involving cookers were reported to have caused the build-up of unsafe levels of carbon monoxide this year. This year s appliance misuse involved using appliances that had either been tampered with or damaged in some way. One fatal incident was the result of towels obstructing the air intake after someone had removed the appliance casing and inserted them. Sub-standard servicing had a contributory score of 8%. Although this was lower than average it was up slightly from last year s score of 6%. Sub-standard servicing included not replacing the boiler case cover properly which is especially important for room-sealed pressurised case boilers. The circumstances surrounding two fatalities from last year, the full details of which were only received this year (see Appendix C first incident), have shown they were the result of a malfunctioning room-sealed pressurised case boiler. The causes were described by the investigator as an appliance fault, an appliance installation fault and a flue/terminal fault. Room-sealed pressurised case boilers are particularly vulnerable to leakage if the seal on the boiler casing is not remade satisfactorily. The option of a sub-standard compartment causing an incident had the lowest contributory score of 1%. Last year it scored zero and although the gas industry has known for sometime that sub-standard installations in compartments can cause a more rapid spread of carbon monoxide around a property than those located outside compartments this has rarely been specified by investigators as the cause of an incident for at least two years. Gas Safety Trust Carbon Monoxide Incident Report 2010 38
3 Conclusions and recommendations i) Although the number of fatalities in 2009/10 was significantly lower than 2008/09, the overall number of reported incidents was almost the same and was considerably higher than in the immediately previous years. The similarity between the numbers of incidents reported this year and last year may be a consequence of the relatively cold winters. It is therefore suggested that an analysis of the 10 previous years average day and night time temperatures be made to see whether there is any correlation with incident numbers. ii) This year the severity of injury reported has, on the whole, tended to be less serious. Furthermore, supplementary information made available to Downstream Gas by the Emergency Service Provider via British Gas showed there have been a number of instances where an occupant has been alerted to the presence of carbon monoxide and this has prevented the escalation of events into a RIDDOR reportable incident. During 2009/10, the prevalence of audible carbon monoxide alarms as reported by incident investigators was greater than in previous years. iii) Lack of servicing was the most commonly reported reason to be the cause of an incident. This year older appliances have featured disproportionately in incidents. It is therefore concluded that there may well be an issue with adequate servicing of older appliances. iv) This year, there were 4 incidents reported, of which 2 were fatal, where a warning notice had been left at the property prior to the incident occurring. Warning notices are designed to inform occupants of the details of unsafe appliances and how to deal with them although it seems that some occupants do not appear to have been aware of the consequences if these notices are ignored. This year the number of fatalities would have been halved if the occupants had acted appropriately. It draws into question the effectiveness of the warning notice classification scheme and suggests a review may be in order. v) There were a number of installations where a working visit had been made within 12 months of an incident occurring. This should not be happening as any such working visit should identify and address potential issues with the installation. The occupant should then reasonably expect the installation to operate safely for at least the next twelve months. This draws into question the competency of some operatives and may support the need to review competency nationwide. vi) The accuracy and completeness of the information in this report relies on the incident investigator completing all the relevant sections on the DIDR form. Whilst every care should be taken by the investigator when completing the form there are some instances when access to the full report by Downstream Gas would provide a better understanding of the factors involved in the incident and maximise the information on the carbon monoxide incident database. vii) This report tends to compare figures year on year rather than looking back over a longer period. It is recommended that the opportunity should be taken to compare more extensively the information published in the last 10 yearly reports as this would be expected to further reveal trends associated with carbon monoxide incidents. viii) Although the proportion of incidents investigated fully has increased over previous years there were still a number that appeared to meet the RIDDOR reporting criteria that had not been adequately investigated. It should be remembered that the law requires the gas supplier to conduct a full investigation whenever possible. Failure to investigate can lead to an incomplete picture being presented in the annual report. It could also leave scope for a further incident to occur. Gas Safety Trust Carbon Monoxide Incident Report 2010 39
ix) The risk level in terms of fatalities remains within the acceptable limit of 1 per million people at risk per year. However, it may still be possible to further reduce the level of risk. In the past, for example, the risk in the privately rented sector has tended to be greater but the indications are that this risk level continues to fall. x) There is some evidence to suggest that a geographical hotspot for carbon monoxide incidents exists in the Cardiff postcode area. It is recommended that previous yearly reports are examined for other possible hotspots in relation to RIDDOR reportable incidents. Greater engagement with the Welsh Assembly and more understanding and evaluation is required to address this serious issue. Gas Safety Trust Carbon Monoxide Incident Report 2010 40
4 References 1. Hayton J, Moore M, Pool G and Moseley J, A review of carbon monoxide incident information, for 2007/8, produced from the full investigation of incidents which involved piped natural gas and LPG, within Great Britain, CORGI Trust, 2009 2. UK population estimates 1971 2009, Office of National Statistics, 2010 3. Social Trends Survey, 2010, No 40, July 2010 4. Statistical Tables, HR Neave Routledge, 2002. 5. General Household Survey (Longitudinal), Office for National Statistics, 2007. 6. English House Condition Survey 2007 Annual Report, Communities and Local Government, September, 2009 7. English Housing Survey, Headline report 2008-9, Department for Communities and Local Government, February 2010 8. Energy Consumption in the UK, Domestic data tables, 2010 Update, Office of National Statistics, July 2010 9. Crowther M, Forrester H and Wood M, Assessment of the size and composition of the UK gas appliance population. DTI. GAC3407, 2005. 10. Energy Saving Trust Website. 11. The Gas Industry Unsafe Situations Procedure, Edition 6, Gas Safe Register, October 2009. 12. http://www.metoffice.gov.uk/climate/uk 13. Hayton J, Moore M, Pool G and Moseley J, A review of carbon monoxide incident information, for 2008/9, produced from the full investigation of incidents which involved piped natural gas and LPG, within Great Britain, CORGI Trust, 2009 14. Heating and Hot Water Industries Council, Market Updates 2008, 2009 and 2010, http://www.centralheating.co.uk/news/category/market-reports 15. Reducing Risks, HSE s Decision-Making Process, 2001, HSE Books Gas Safety Trust Carbon Monoxide Incident Report 2010 41
Appendix A: DIDR LPG incidents Details of two LPG incidents were provided during the 2009/10 period. One occurred in March 2009 and hence relates to the 2008/09 year, the details of this have been presented in Appendix C. The other LPG incident occurred in the Devon postcode area of EX13 at 18.00hrs on 15th October 2009. It resulted in two non-fatal casualties, a male and a female both aged over 65. The female was hospitalised for less than 24 hours for tests. At the time of the incident, stated as 18:00, the male was located in the living room/lounge and the female was in the bedroom. The property was an owner occupied detached house reportedly built between 1966 and 1980. The property had double glazed windows and a solid ground floor. The incident appliance was identified as a Vaillant Ecomax wall mounted combi boiler manufactured during 2001 and was located within the ground floor utility room. The Ecomax is a condensing boiler, with a room sealed fanned draught flue. The boiler casing was of the negative pressurise design. The boiler was new when it was installed by a registered operative and the flue and installation were to current standards. It had been serviced by a registered operative within 6 months of the incident. Prior to the incident there had been no reports of fumes from the appliance. The investigation found that the exhaust duct was cracked and broken, and that there was corrosion around the condensate drain from the heat exchanger. The incident cause was stated as not known. Appendix B: DIDR non-domestic incidents No non-domestic incidents were received on DIDR forms. Gas Safety Trust Carbon Monoxide Incident Report 2010 42
Appendix C: Past incidents previously unreported There were three incidents from previous years that have been reported since the completion of last year s report. Two of these were as a result of the use of piped natural gas and the third was as a result of the use of LPG. Details of these incidents are given below. The information from these incidents has been added to the carbon monoxide incident database and the relevant historical charts and tables have been updated accordingly within the main body of this report. The fatality figures of report 2008/9 included the first incident number 1; it was the details that were received after the 2008/9 was completed. Incident 1 (Natural gas) This double fatality occurred at 08.00hrs on 20 April 2010 in the London postcode area E10. The owner occupiers of the semi-detached property were a male aged 74 and a female aged 71. The house was built in 1950 and had a suspended ground floor and double glazed windows. The appliance involved was a Potterton Netaheat wall mounted central heating boiler. It was located in a compartment/cupboard off the ground floor hallway. This boiler features a room sealed, fanned flue and operates with the case under a positive pressure. Such a configuration has been noted to feature in a number of previous serious incidents within this series of reports. Details of the boiler installation were not reported but the investigator confirmed that with the exception of the compartment ventilation it had been installed in accordance with the standards current at the time The investigator reported the boiler appeared to be in need of servicing, the CO/CO 2 ratio was high and specific problems existed with the flue. There was a flue installation fault and a blockage/restriction both as a result of subsequent building construction work. When tested in the as found condition high levels of carbon monoxide entered the property. The incident causes were described as an appliance fault, an appliance installation fault and a flue/terminal fault One further appliance at the property was found to be not to current standards. Incident 2 (Natural gas) This occurred during November 2008 in the London post code area of SW20. A female aged 76 suffered from carbon monoxide poisoning and when tested during the evening of the incident her COHb level was 5.2%. The terraced house was owner occupied and was constructed pre 1945. It had part solid floors and some double glazing. The appliance was a Kohlangaz Kamina inset live fuel effect gas fire fitted on the ground floor. The installation was not satisfactory and did not comply with the manufacturer s instructions. Faults reported were that the fire base was not sealed, which affected the flue pull and that the coal bed was incorrectly positioned. Chimney pots were fitted at different heights. The flue system was a brick chimney and was to current standards. It passed a flue flow and continuity check. The flue exited the property via a chimney pot. A vitiation device was fitted to the appliance and this was reported to be operational. A battery powered carbon monoxide alarm, to BS:7860 manufactured by SF Detection, was located in the same room as the fire. It was checked and proved to be operational. It was reported that the alarm had sounded an alert at the time of the incident. Gas Safety Trust Carbon Monoxide Incident Report 2010 43
The on-site checks showed that the fire gas rate was correct, but that the installation failed a spillage test. Low levels of carbon monoxide were found to enter the property when the fire was tested. The fire was covered by a regular service contract and had been serviced by a registered operative between 6 and 12 months prior to the incident. The casualty was a smoker and it was not possible for the investigator to prove that the low levels of carbon monoxide, emitted at the time of the incident and which triggered the carbon monoxide alarm, had caused increased levels of COHb. Incident 3 (LPG) During March 2009 a double fatality involving LPG was reported in the NP4 Monmouthshire post code area. The incident occurred in a garden summer house. The summer house was single glazed and had a partial solid floor. The appliance was a flueless Super Ser Orbaiceta cabinet heater. The investigator reported that a radiant plaque was broken and that there were rust holes in the back of heater behind the radiant plaques. The heater control button was not fully operational. During the carbon monoxide build up test a level above 800 ppm of carbon monoxide was measured within the summer house. The causes of the incident were given as a ventilation fault, a lack of servicing and misuse of the heater. Gas Safety Trust Carbon Monoxide Incident Report 2010 44
W www.gas-safety-trust.org.uk T 01256 548 020 E info@gstrust.org.uk The Gas Safety Trust, Unit 7, Prisma Park, Berrington Way, Basingstoke, Hampshire, RG24 8GT, UK Registered Charity Number 1110624 Gas Safety Trust 2010