Radon Survey Summary Report

Transcription

1 GWASANAETHAU IECHYD A DIOGELWCH - HEALTH AND SAFETY SERVICES ADRODDIAD REPORT Radon Survey Summary Report September 2010 Gwasanaethau Iechyd a Diogelwch Health and Safety Services, Penbre, Lon y Coleg. LL57 2DG Tel: Ebost: Iechydadiogelwch@bangor.ac.uk healthandsafety@bangor.ac.uk Fax:

2 1. SUMMARY Radon is a colourless, odourless gas that originates from uranium in rocks. Long term exposure to very high levels of radon has been linked to lung cancer. The Management of Health and Safety at Work Regulations 1999 require the assessment of health and safety risks including radon in the workplace under certain circumstances, for example where underground workplaces exist and where premises are in a radon affected area. As such the University has undertaken a number of radon surveys since May 2009 to identify workplace radon concentrations. This involved the placement of Health Protection Agency (HPA) supplied radon monitors at a number of locations. After three months, the monitors were analysed by the HPA to compare radon measurements against the action level of 400 Bq m 3 (workplaces) and 200 Bq m 3 (residential accommodation) designated in the Ionising Radiation Regulations (IRR) A Preliminary Survey to identify workplaces wholly / partially underground led to radon monitors being placed in 40 locations between May and August Two areas were identified as exceeding the action level with a further two, although below the action level requiring further investigation because of high room usage and limited ventilation. However, as the readings were taken outside of the winter period, when it is felt radon concentrations are highest, the HPA applied a winter corrected factor. This seasonal adjustment takes account of the fact that ventilation levels in winter are generally lower as windows are closed and buildings are warmer relative to the ground causing increased radon seepage. As a result the University was advised to re-measure radon levels during the winter period to obtain true measurements. The Second Survey involved the placement of 23 radon monitors from December 2009 February 2010 in the areas identified by the Preliminary Survey and the immediate surrounding areas. As a precaution, a review of local geological maps and a post code search was also undertaken. This resulted in a Third Survey starting two weeks after the Second Survey with 39 monitors placed across the Normal Site and Treborth Site. The Second Survey identified one elevated radon level of 490 Bq m 3 in the George Building. However a significant reduction in the radon levels identified as a concern during the Preliminary Survey were seen; 570 & 650 Bq m 3 in Westbury Mount to 70 & 90 Bq m 3, 330 Bq m 3 in Nantlle to 120 Bq m 3 and 370 Bq m 3 in Main Arts to 80 Bq m 3. This highlights the risk of anomalies when measurements are winter corrected. In addition, the Third Survey identified two areas with elevated radon levels; one a residential property (240 Bq m 3 ) at Treborth and the second a high usage office building (850 Bq m 3 ) at Normal Site. On advice from the HPA and the RPA a Fourth Survey was undertaken by the RPA of the residential property and office building using a Durridge Rad 7 Electronic Radon Detector. The results of the Fourth Survey have led to the office building being vacated pending remedial works to prevent radon seepage. In addition, a further survey is planned of the residential property during the winter period. Elevated radon levels were reported to the Health and Safety Executive with advice also sought from the HPA and the University s Radiation Protection Adviser (RPA) with regards to what further action should be taken. 2. SCOPE OF REPORT The scope of the Preliminary Survey, funded through the Safety Executive Task Group (SEG) was to identify the work areas across the University estate with the potential for high radon concentrations. Radon 1

3 measurements were then undertaken in these areas, with the findings of the Preliminary Survey directing further surveys and action. 3. BACKGROUND Radon is a radioactive gas which originates from uranium that occurs naturally in many rocks and soils. Granite contains relatively high levels of uranium and granite areas of the UK, such as the South West of England have very high radon concentrations. However, high radon areas are not restricted to the South West and many parts of Wales are also affected (see Appendix A). Radon can seep out of the ground and build up in houses and in-door workplaces. The highest radon concentrations are usually found in underground spaces such as basements, caves and mines but high concentrations can also be found in the ground floor of buildings as well. Most radon gas breathed in is immediately exhaled and present little hazard. However, decayed products of radon behave more like solid materials and attach themselves to atmospheric dust and water droplets which are then breathed in, becoming lodged in the lungs and airways. Some of these decayed products emit a particularly hazardous type of radiation know as alpha particles which can cause significant damage to cells in the lung. Radon is now recognised to be the second largest cause of lung cancer in the UK after smoking. Because of the hazardous nature of radon, legislation exists that requires employers to protect their employees from exposure to radon in the workplace. The Management of Health and Safety at Work Regulations 1999 require the assessment of health and safety risks from radon under certain circumstances. As some areas of Wales are affected by radon and some University buildings contain work areas that are either wholly or partially below ground, a preliminary radon assessment was carried out as a precaution. 4. METHODOLOGY The Preliminary Survey measured radon concentrations in workplaces with the highest potential radon exposure risk to identify if a wider ranging survey was required. It involved an examination of the University estate, with locations either wholly or partially underground identified. Each area was then risk rated as High, Medium and Low using the following qualitative scoring method: Room usage (duration and numbers of occupants) The extent to which the room is built into the ground The level of natural or mechanical ventilation available A total of 40 locations were selected with radon monitors, purchased from the HPA deployed between May to August The HPA results subsequently initiated the Second and Third Surveys which involved the placement of 62 radon monitors from December 2009 to February The results of the Third Survey led to an immediate Fourth Survey of affected areas. This latter survey involved use of a Durridge Rad 7 Electronic Radon Detector to take five-minute air samples throughout the affected buildings. Each air sample was filtered, dried and analysed within the internal silicon surface barrier detectors of the Rad 7 for radon (222Rn) and thoron (220Rn) decay progeny. In the sniffer mode, set during the tests, the Rad 7 automatically calculated the concentration of radon and thoron at the end of the 5 minute sampling period. Because of the very short half life of thoron (56 seconds) this radioisotope tends to only be detected very close to its source so can be used as an indicator of where thoron (and by inference radon) is entering a room. 2

4 5. RESULTS AND ACTIONS The following show the results from the four surveys. All actions were undertaken in accordance with advice from the HPA and RPA: PRELIMINARY SURVEY Period (3 months) May August 2009 Number of radon monitors placed 40 Main Arts, New Arts Library, College Road Houses, Music Building, Cae Derwen, Management Centre, John Morris Jones, JP Hall, Nantlle, Treborth, Westbury Mount, Craig Mair, Alun Roberts, Charles Evans, Brambell, Thoday, Students Union, Electronic Engineering Results Westbury Mount 570 & 650 Bq m 3 Main Arts 370 Bq m 3 Nantlle 330 Bq m 3 Information and guidance provided to staff in Westbury Mount and Nantlle Records kept of Westbury Mount room usage Second Survey planned for winter period to eliminate winter correction of values SECOND SURVEY Period (3 months) December 2009 February 2010 Number of radon monitors placed 23 Main Arts, Westbury Mount, Craig Mair, Nuffield Fish Laboratories, Ynys Faelog, Effionyd, George Building, Nantlle, Students Union Results George Building 490 Bq m 3 NOTE: Measurements for the locations previously identified with elevated levels were significantly reduced: Westbury Mount 70 & 90 Bq m 3 Main Arts 80 Bq m 3 Nantlle 120 Bq m 3 Information and guidance provided to staff in the George Building Access control measures implemented Records kept of room usage 3

5 THIRD SURVEY Period (3 months) December 2009 February 2010 Number of radon monitors placed 39 Ardudwy, Hiraethog 1 & 2, Library, Nantlle, Dinas, Gym, Stable Block, Wern, Rhos, Trefenai, Cilgwyn, Effionyd, George Building, Bistro, Padarn, Meirion, Arfon & Seiriol (Halls of Residence), Treborth (including accommodation) Results Ardudwy 850 & 310 Bq m 3 Treborth (house) 240 Bq m 3 Information and guidance provided to staff in Ardudwy and Treborth Immediate Fourth Survey of Ardudwy and Treborth undertaken by RPA FOURTH SURVEY Period (2 days) 18 th 19 th May 2010 Number of Readings taken using a Durridge Rad 7 Electronic Radon Detector 60 Ardudwy 10 Treborth (house) Ardudwy, Treborth (house) Results Ardudwy 798 Bq m 3 (highest) NOTE: Ardudwy readings altered significantly throughout the day. For example, the above reading taken at 13:26 reduced to 347 Bq m 3 by 16:05. This could be attributed to the movement of sun throughout the day, increasing / decreasing room temperature and the opening / closing of doors increasing ventilation Treborth (accommodation) 69.1 Bq m 3 (highest) Winter survey planned of Treborth Ardudwy vacated pending remedial works to prevent radon seepage 4

6 APPENDIX A Indicative Radon affected areas across North Wales 5