Research Program Area: Health & Exposure
Topic Areas: Health Effects of Air Pollution
This report describes a laboratory and field pilot study designed to investigate personal and indoor exposures to particulate matter. The primary goal of this research project was to develop needed methods of measurement and characterization of exposures to airborne particles equal to or less than 10 micrometers in diameter (PM10). Using fully developed and tested methods, it should be possible to provide improved dose estimates for PM10 and to relate PM10 and its associated components to health effects. Exposure to particulate matter is currently assessed using fixed-site monitors that may not accurately measure exposure of humans to particles. This study focuses on personal exposure and indoor concentration, since a person typically spends 80-90% of the day indoors.
In the study three sampling devices were used and compared for measurement of PM10 particles: 1) an air pump and sampler specifically designed to collect PM10 particles in indoor environments; 2) an industrial hygiene-type (cyclone) sampler designed to measure personal exposure to inhalable aerosols; and 3) a multistage personal (cascade) sampler designed to quantify concentration for several particle sizes. Filters from these samplers were analyzed for concentration of particles in air, concentration of potentially acid-forming ionic compounds, and mutagenic activity. Ancillary samples were taken for nicotine and biological aeroallergens. Nicotine is a specific marker for tobacco smoke, which has a large impact on indoor particulate matter, and aeroallergen concentration is a necessary control variable when investigating the effects of air pollution on the health of allergic asthmatics (the subjects who took part in this study).
This pilot study was conducted in three phases. First, all methods were tested and background concentrations established in laboratory studies; next, two homes were selected for pretesting; finally, measurements were made in eight homes of asthmatics. This pilot study successfully demonstrated the feasibility of monitoring the mass of particles equal to or less than 10 micrometers diameter inside and outside of residential settings and for measurement of personal exposures.
All of the sampling devices tested in this study reproducibly collected particles both indoors and outdoors. Differences observed between sampler types were expected based upon the designed size cutoffs of the samplers. Indoor particle concentrations were generally lower than outdoor concentrations in the nonsmoking residences in this study. Further, mass concentrations of indoor particles were, correlated with outdoor concentrations which indicated the importance of ambient pollutants on indoor air. Indoor sulfate concentrations were similar to and highly correlated with outdoor concentrations, suggesting again the importance of outdoor sources. Indoor nitrate concentrations, in contrast, were lower than outdoor concentrations and were not well correlated with concurrent outdoor measurements. Several factors led to the conclusion that a portion of the nitrate aerosol is contained in larger particles that do not efficiently penetrate into the home or that settle from indoor air. Mutagenic activity of particles was generally greater outdoors, and associated with the smallest particles; indoor activity correlated with outdoor levels. Aeroallergen concentrations were generally higher outdoors than indoors. Nicotine measurements indoors were generally below detectable limits which confirmed that smoking did not occur in these homes. Personal monitoring results indicated that exposure to particle mass and its components was most directly related to indoor residential measurements.
This pilot study has successfully confirmed that indoor and personal measurements of PM10 mass and its components is feasible and could be extended to large-scale health and exposure assessment studies.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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