Assessing Near-Field Exposures from Distributed Residential Wood Smoke Combustin Sources

摘要

In many communities, residential wood burning produces a significant fraction of wintertime PM(sub 2.5). This study investigated the impact of near-field burning sources on exposures. Wood smoke samples, meteorological data, and burning source location were analyzed for 15 nights within a 1 km(sup 2) area in Cambria, CA. Black carbon, a significant component of soot, served as an indicator compound for wood smoke. Large concentration variations were observed each night both at a single location and between locations. The standard deviation of 12 hour integrated concentrations measured at all sites ranged from 20 percent to 150 percent of the average on any given night. Sites with the highest overall concentrations (averaged over all nights) were 2 to 10 times higher than the lowest concentration sites. Neither multiple linear regression nor dispersion models yielded a strong representation of measured concentrations. Thirteen indoor/outdoor measurement pairs from 4 different residences showed an average indoor/outdoor concentration ratio of 0.88 - 0.41. Based on measured concentrations, the intake fraction calculated using near-field concentrations was 25 percent higher than that calculated using the average concentration for the region. This study demonstrates that near-field effects can lead to higher exposures for some individuals than would be predicted using regional monitors.