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Particulate matter (PM) ranks as one of the principal air pollutants linked to acute and chronic physiological ailments. Sized 200 times smaller than a grain of sand, PM is generated by both natural and anthropogenic sources with the latter primarily consisting of fuel combustion processes from utilities, vehicles, and industrial emitters.1 Since 1987, the U.S. Environmental Protection Agency (EPA) has set an air quality standard for inhalable “coarse ” PM sized less than 10 µm (PM10) and in 1997, the agency set stricter standards for “fine ” PM, defined to be sized less than 2.5 µm (PM2.5).2 This action was taken to address determinations of greater health risks associated with PM in this category. A subsequent revision in 2006 further highlighted the recognized size-based health risk distinctions by respectively tightening and eliminating the 24-hour PM2.5 and annual PM10 standards.