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PERSONAL, INDOOR, AND OUTDOOR CONCENTRATIONS OF PM2.5, PARTICULATE NITRATE, AND ELEMENTAL CARBON FOR INDIVIDUALS WITH COPD IN LOS ANGELES, CA
Citation:
Chang, L. T., H. H. Suh, A. Wheeler, P. Koutrakis, G. Lau, B. Turpin, S. Colome, AND L A. Wallace. PERSONAL, INDOOR, AND OUTDOOR CONCENTRATIONS OF PM2.5, PARTICULATE NITRATE, AND ELEMENTAL CARBON FOR INDIVIDUALS WITH COPD IN LOS ANGELES, CA. Presented at International Society of Exposure Analysis 2002 Conference, Vancouver, Canada, August 11-15, 2002.
Impact/Purpose:
The primary study objectives are:
1.To quantify personal exposures and indoor air concentrations for PM/gases for potentially sensitive individuals (cross sectional, inter- and intrapersonal).
2.To describe (magnitude and variability) the relationships between personal exposure, and indoor, outdoor and ambient air concentrations for PM/gases for different sensitive cohorts. These cohorts represent subjects of opportunity and relationships established will not be used to extrapolate to the general population.
3.To examine the inter- and intrapersonal variability in the relationship between personal exposures, and indoor, outdoor, and ambient air concentrations for PM/gases for sensitive individuals.
4.To identify and model the factors that contribute to the inter- and intrapersonal variability in the relationships between personal exposures and indoor, outdoor, and ambient air concentrations for PM/gases.
5.To determine the contribution of ambient concentrations to indoor air/personal exposures for PM/gases.
6.To examine the effects of air shed (location, season), population demographics, and residential setting (apartment vs stand-alone homes) on the relationship between personal exposure and indoor, outdoor, and ambient air concentrations for PM/gases.
Description:
This study characterizes the personal, indoor, and outdoor concentrations of PM2.5 and the major components of PM2.5, including nitrate (NO3-), elemental carbon (EC), and the elements for individuals with chronic obstructive pulmonary disease (COPD) living in Los Angeles, CA. Monitoring was performed for 15 participants for 7 consecutive days in the winter and summer of 2000, respectively. During each sampling day, 24-hr personal, indoor, and outdoor samples of the targeted pollutants was collected simultaneously. Housing characteristic information and time-activity diaries were also obtained.
In each season, participants reported spending approximately 87% of each day within their residences. The overall 24-hr mean personal exposures to PM2.5, NO3-, and EC were 22.40 (+18.17), 1.43 (+1.06), and 1.13 (+1.20) g/m3, respectively. Significant seasonal differences were found for all of the PM2.5, NO3- and EC measures, except for outdoor NO3-, where no seasonal difference was observed. Personal PM2.5 exposures were higher than corresponding indoor and outdoor concentrations in both seasons, while the same pattern was not persistent among the major components of PM2.5. Higher outdoor nitrate concentrations, as compared with the corresponding measurements, were found in both seasons, which reflects the fact that the major sources of nitrate are from motor vehicles. Additionally, a similar but less distinct pattern was shown for elemental carbon concentrations.
Personal exposures were significantly correlated with both indoor and outdoor concentrations for PM2.5, NO3-, and EC in both seasons, as were those between indoor and outdoor concentrations. The association between personal PM2.5 exposures and corresponding outdoor levels was stronger in the summer (Spearman correlation coefficient, rs = 0.62), as compared to that in the winter (rs = 0.52). In addition, indoor PM2.5 concentrations were more strongly correlated with personal exposures during the wintertime (rs = 0.77), as compared to the summertime (rs = 0.63). Longitudinal analyses were conducted to account for the repeated measurements for each subject. For PM2.5, the relationship between personal exposures and indoor/outdoor concentrations followed patterns observed in previous studies, where the effect of indoor concentrations on personal exposures became more dominant in the winter due to the low air exchange rate.
This work has been funded by the U.S. Environmental Protection Agency under EPA Cooperative Agreement number (CR 827159-01-0). It has been subjected to Agency review and approved for publication.