With increasing evidence of adverse Hlth. effects Assoc. with particulate matter (PM), the exposure impact of Nat. sources, such as forest fires, has substantial Pub. Hlth. relevance. In addition to the threat to nearby communities, pollutants released from forest fires can travel thousands of kilometers to heavily populated urban areas. There was a dramatic increase in forest fire Activ. in the Prov. of Quebec, Canada, during July 2002. The Transp. of PM released from these forest fires was examined using a combination of a moderate-resolution imaging spectroradiometer satellite image, back-trajectories using a hybrid single-particle Lagrangian Intgd. trajectory, and Loc. light detection and ranging measurements. Time- and size-resolved PM was evaluated at three ambient and four indoor Msrmt. sites using a combination of direct reading Instrum. (laser, time-of-flight aerosol spectrometer, nephelometer, and an oscillating microbalance). The Transp. and monitoring results consistently identified a forest fire related PM episode in Baltimore that occurred the first weekend of July 2002 and resulted in as much as a 30-fold increase in ambient fine PM. On the basis of tapered element oscillating microbalance measurements, the 24 h PM2.5 concentration reached 86 μg/m3 on July 7, 2002, exceeding the 24 h Natl. ambient air Qual. standard. The episode was primarily comprised of particles less than 2.5 μm in aerodynamic diameter, highlighting the preferential Transp. of the fraction of PM that is of greatest Hlth. concern. Penetration of the ambient episode indoors was efficient (median indoor-to-outdoor ratio 0.91) such that the high ambient levels were similarly experienced indoors. These results are significant in demonstrating the impact of a natural source thousands of kilometers away on ambient levels of and potential exposures to air pollution within an urban center. This research highlights the significance of transboundary air pollution and the need for studies that assess the public health impacts associated with such sources and transport processes.
ASJC Scopus subject areas
- Environmental Chemistry