Comparison of Fine Particle Measurements from a Direct-Reading Instrument and a Gravimetric Sampling Method

Abstract

Particulate air pollution, specifically the fine particle fraction (PM _2.5 ), has been associated with increased cardiopulmonary morbidity and mortality in general population studies. Occupational exposure to fine particulate matter can exceed ambient levels by a large factor. Due to increased interest in the health effects of particulate matter, many particle sampling methods have been developed. In this study, two such measurement methods were used simultaneously and compared. PM _2.5 was sampled using a filter-based gravimetric sampling method and a direct-reading instrument, the TSI Inc. model 8520 DUSTTRAK aerosol monitor. Both sampling methods were used to determine the PM _2.5 exposure in a group of boilermakers exposed to welding fumes and residual fuel oil ash. The geometric mean PM _2.5 concentration was 0.30 mg/m ³ (GSD 3.25) and 0.31 mg/m ³ (GSD 2.90) from the DUSTTRAK and gravimetric method, respectively. The Spearman rank correlation coefficient for the gravimetric and DUSTTRAK PM _2.5 concentrations was 0.68. Linear regression models indicated that log _e DUSTTRAK PM _2.5 concentrations significantly predicted log _e gravimetric PM _2.5 concentrations (p < 0.01). The association between log _e DUSTTRAK and log _e gravimetric PM _2.5 concentrations was found to be modified by surrogate measures for seasonal variation and type of aerosol. PM _2.5 measurements from the DUSTTRAK are well correlated and highly predictive of measurements from the gravimetric sampling method for the aerosols in these work environments. However, results from this study suggest that aerosol particle characteristics may affect the relationship between the gravimetric and DUSTTRAK PM _2.5 measurements. Recalibration of the DUSTTRAK for the specific aerosol, as recommended by the manufacturer, may be necessary to produce valid measures of airborne particulate matter.

Keywords:

• aerosol sampling methods
• DUSTTRAK aerosol monitor
• fine particulate matter (PM_2.5)
• occupational exposure

ACKNOWLEDGMENTS

The authors are grateful to Stephen Rudnick, Ema Rodrigues, Jaime Hart, and Sutapa Mukherjee for assistance. Special thanks to the staff and members of the International Brotherhood of Boilermakers, Iron Ship Builders, Blacksmiths, Forgers, and Helpers of Local No. 29, Quincy, Massachusetts, and the Thomas O'Connor Company.

This study was supported by National Institutes of Health (NIH) grants ES09860 and ES0002, and NIOSH grant OH00152.

Notes

^A Standard deviation shown in parenthesis.

^B Geometric standard deviation shown in parenthesis.

^A Smoking status samples restricted to personal samples (n = 39).

^A p < 0.05.

^B Smoking status model also is adjusted for sample type.

^A p < 0.05.

^B Smoking status model also is adjusted for sample type.