The Influence of Human Activity Patterns on Personal PM Exposure: A Comparative Analysis of Filter-Based and Continuous Particle Measurements

Abstract

Particulate matter (PM) exposure data from the U.S. Environmental Protection Agency (EPA)-sponsored 1998 Baltimore and 1999 Fresno PM exposure studies were analyzed to identify important microenvironments and activities that may lead to increased particle exposure for select elderly (>65 years old) subjects. Integrated 24-hr filter-based PM 2.5 or PM 10 mass measurements [using Personal Environmental Monitors(PEMs)] included personal measurements, indoor and outdoor residential measurements, and measurements at a central indoor site and a community monitoring site. A subset of the participants in each study wore passive nephelometers that continuously measured (1-min averaging time) particles ranging in size from 0.1 to ~10 µm. Significant activities and locations were identified by a statistical mixed model (p < 0.01) for each study population based on the measured PM 2.5 or PM 10 mass and time activity data. Elevated PM concentrations were associated with traveling (car or bus), commercial locations (store, office, mall, etc.), restaurants, and working.The modeled results were compared to continuous PM concentrations determined by the nephelometers while participants were in these locations. Overall, the nephelometer data agreed within 6% of the modeled PM 2.5 results for the Baltimore participants and within ~20% for the Fresno participants (variability was due to zero drift associated with the nephelometer). The nephelometer did not agree as well with the PM 10 mass measurements, most likely because the nephelometer optimally responds to fine particles (0.3-2 µm). Approximately onehalf (54 ± 31%; mean ± standard deviation from both studies) of the average daily PM 2.5 exposure occurred inside residences, where the participants spent an average of 83 ± 10% of their time. These data also showed that a significant portion of PM 2.5 exposure occurred in locations where participants spent only 4-13% of their time.

Personal exposure monitoring wearing protocol compliance: An initial assessment of quantitative measurement

“…Comparison of each participant's nephelometer concentration traces with their time --activity diaries for potential PM generating activities such as cooking confirmed this conclusion. 12,13,29 Quantitative assessment of personal exposure monitor wearing compliance should be more useful than evaluation of recruitment and retention efforts or exploring sociological differences between participants. One goal of personal sampler wearing compliance monitoring is reducing exposure misclassification that results from non-compliant personal samples providing unrepresentative exposure data.…”

Influence of traffic patterns on particulate matter and polycyclic aromatic hydrocarbon concentrations in Roxbury, Massachusetts

“…Although humidity and other factors will influence this relation, these variations are minimized by sampling in a defined geographic region in a single season. Furthermore, a focus on PM 2.5 rather than PM 10 is likely to improve the relation between our measures and gravimetric concentrations (Quintana et al, 2000;Rea et al, 2001). Thus, our regression models and evaluations of spatial heterogeneity based on DustTrak data will be interpretable.…”

Field performance of a nephelometer in rural kitchens: effects of high humidity excursions and correlations to gravimetric analyses

“…Portable nephelometers have been welcomed as an advancement for assessment of human exposures to particles (Radojevic and Hassan, 1999;Ezzati et al, 2000a, b;Muraleedharan and Radojevic, 2000;Quintana et al, 2000Quintana et al, , 2001Williams et al, 2000;Rea et al, 2001;Lanki et al, 2002;Liu et al, 2003;Wallace et al, 2003Wallace et al, , 2006Balakrishnan et al, 2004;Wu et al, 2005a). However, most previously published environmental investigations of nephelometer performance relative to gravitational determinations depict controlled laboratory settings or relatively low (1-60 mg/m 3 ) particle concentrations (Richards et al, 1999;Howard-Reed et al, 2000;Quintana et al, 2000;Sioutas et al, 2000;Lanki et al, 2002;Liu et al, 2002;Wallace et al, 2003Wallace et al, , 2006Allen et al, 2004;Chakrabarti et al, 2004;Jenkins et al, 2004;Wu et al, 2005b).…”