Integrating Nephelometer - Visibility and Particulate Monitoring. Summary

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2 Summary This paper investigate the correlation between the Aurora 1000 integrating Nephelometer single wavelength green source 525 nm and the Thermo Fisher 1400A/B TEOM, Met-One 1020 BAM, and FRM sampler. A number of experiments have been conducted and results presented. It indicates the potential use of the nephelometer as a real time PM2.5 particulate monitor.

3 Integrating Nephelometer Visibility and Particulate Monitoring Robert Dal Sasso AWMA Xian, China May 2010

4 Introduction The integrating nephelometer has, for over 40 years, been used for the measurement of visibility in air quality monitoring stations and studies. Nephelometers provide accurate measurements of light scattering, in both wet and dry samples, and allow calculations of visible distance to be made. Reporting of visible distance is recognized as an important air quality indicator for many monitoring agencies as its units of visible distance (reported in kilometers) is easily understood by the general public. During the course the its deployments in many sites, it was observed that the nephelometer reading correlates very well with the measurements of various PM2.5 particular monitors, including Beta Attenuation Monitors (BAM) and Tapered Element Oscillating Monitors (TEOM s) and FRM samplers More recently multiple studies involving the nephelometers used as an alternative particulate monitor have created unique opportunities for air quality monitoring, specifically real-time mass measurement including indicators of changes in particulate source.

5 Experimental evidence The integrating nephelometer are now also being used in multiple studies for the measurement of particulate matter in real-time. The Aurora nephelometer has been used in comparisons with Beta Attenuation Monitors (BAM), Tapered Element Oscillating Monitors (TEOM s) and FRM samplers. The results of these studies have been presented in other papers. These studies have found strong correlations between the nephelometer s light scattering coefficient and mass measurement (mg/m 3 ). From these studies it has been found that a nephelometer can report accurate mass measurement data in real time, through the use of a unique, site specific, offset and where particle source is relatively stable.

6 University of Mexico FRM pm2.5 collected on a nylon filter and nephelometer The precision of the collocated Nephelometer and FRM PM 2.5 sampler in University of Mexico.A total of 9 x 24 hour samples from the FRM sampler collected on a nylon filter and 9 x 24 hour Aurora 525nm nephelometer data averages collected from 5 minutes averages. The data was drawn from May 17 th to June 2009 Data was supplied by Mexico City GDF. The R (0.9777) obtained implies that the two monitoring methods are nearly equivalent for this specific site.

7 University of Mexico

8 Puget Sound Clean Air Agency, State of Washington U.S.A. Continuous (in ug/m3) LYNNWOOD PM 2.5 Continuous vs FRM November 2004 to Present y = x R 2 = FDMS y = x R 2 = TEOM y = x R 2 = Met One BAM y = 0.996x R 2 = NEPH FRM (in ug/m3) BAM NEPH TEOM FDMS Linear (BAM) Linear (FDMS) Linear (NEPH) Linear (TEOM)

9 Traffic tunnel, Melbourne, Australia - 1/10/2008 to 2/11/2008 Results of one month study in a traffic tunnel in Melbourne, Australia where the data of TEOM 1400A/B and Aurora 1000 nephelometer were gathered and compared are plotted below. A strong correlation has been observed. Data were collected according to NATA (ISO17025) accreditation TEOM 1400A/B Aurora 525 nm Nephelometer

10 Traffic tunnel, Melbourne, Australia TEOM PM2.5 Vs ECOTECH AURORA NEPH y = x R 2 = PM2.5 (mg/m3) Visability (km-1)

11 Traffic tunnel, Melbourne, Australia, corrected for particulate monitoring TUNNEL TEOM PM2.5 vs ECOTECH AURORA NEPH R 2 = TEOM PM2.5 (mg/m3) NEPH (mg/m3)

12 Dust Storm in Sydney September 2009 The response time of the Aurora 1000 is much better in such circumstances, as it is a real-time monitoring device. The response time of the nephelometer will result in higher peaks compared to Therm Fisher TEOM 1400A/B this is due to the 300 second rolling average used by the TEOM.

13 Dust Storm in Sydney September 2009 Source DCEEW Web cam Wednesday 23 September 20098

14 Dust Storm in Sydney September 2009 Source DCEEW Web cam Wednesday 23 September 20098

15 Conclusion Results demonstrates that the integrating nephelometer is a simple, low cost, low power, easy to maintain and sensitive instrument. Furthermore, data on both light scattering (for visibility wet measurement) and fine particulate (PM 2.5 dry measurement) mass concentrations can be obtained reliably and importantly in a time effective manner for a rapid assessment of fine particle (PM 2.5 ) air pollution.

16 THANK YOU