Correction factor for continuous monitoring of wood smoke fine particulate matter.

Marcy L Mcnamara,Tony J Ward,Curtis W Noonan

doi:10.4209/aaqr.2010.08.0072

Abstract

The US Environmental Protection Agency (EPA) has designated a handful of instruments as Federal Reference or Federal Equivalency Methods (FRM and FEM, respectively) for the monitoring of fine particulate matter (PM2.5). More commonly used for indoor exposure assessment studies are optical scanning devices such as the DustTrak (TSI) due to the their portability and affordability. It is recommended by the manufacturer of these instruments that a "correction factor" be applied when assessing source-specific conditions. In this study, DustTraks were collocated with multiple samplers in various environments in an effort to establish an indoor, wood smoke-source specific correction factor. The DustTrak was found to report PM2.5 levels on average 1.6 times higher than a filter based method in two indoor sampling programs. The DustTrak also reported indoor PM2.5 concentrations 1.7 times higher than a FRM sampler during a regional forest fire event. These real-world scenarios give a correction factor within a reasonable range of the results of a controlled laboratory experiment in which DustTraks reported PM2.5 approximately 2 times higher than a FEM. Our indoor wood smoke-specific correction factor of 1.65 will allow for DustTraks to be confidently used in quantifying PM2.5 exposures within indoor environments predominantly impacted by wood smoke.

Highlights

Wood smoke is a complex mixture, with many components having well-documented adverse human health effects
First we report on studies that were conducted in a controlled laboratory setting, where DustTraks were compared to an Federal Equivalency Method (FEM) sampler (MetOne BAM-1020) during the burning of a wood stove
PM2.5 has been linked to numerous health outcomes including, but not limited to, cardiovascular diseases and respiratory diseases such as bronchitis, asthma, and pneumonia (Naeher et al 2007; Robin 1996; Neupane et al 2009)

Summary

Introduction

Wood smoke is a complex mixture, with many components having well-documented adverse human health effects. Detected pollutants in wood smoke include fine particulate matter with an aerodynamic diameter of 2.5 microns or less (PM2.5), carbon monoxide, and nitrogen oxides, all of which are regulated in the ambient air by the EPA. Among these regulated pollutants, a comprehensive review by Naeher et al (2007) concluded that PM2.5 serves as the best exposure metric for wood smoke, and tends to be among the most elevated pollutants during exposure events for comparison with existing air quality standards. In a residential study conducted in Libby, MT within 16 homes with older model wood stoves, the average (sd) concentration (as measured by DustTraks) was 51.2 (32.0) μg/m3, with average spike levels of 434 (419) μg/m3 (Ward et al 2008)

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Conclusion