Contribution of industrial and traffic emissions to ultrafine, fine, coarse particles in the vicinity of industrial areas in Japan

Abstract

Atmospheric particulate matter (PM) in industrial areas is typically enriched with potentially toxic trace metals. However, measurements of ultrafine particles (PM0.1) in industrial areas, and the source apportionment of PM0.1 based on these results, are limited. Robust source apportionment studies are therefore necessary in order to identify the source of toxic emissions and to develop measures for reducing such emissions. The present study sought to clarify the contributions to PM mass of ultrafine, fine (PM2.5), and coarse particles (PM10 – PM2.5) in an urban–industrial area with multiple emission sources. We performed both online measurements of PM at a high temporal resolution and size-resolved offline measurements. Source apportionments were then performed for each particle size range by combining a positive matrix factorization method applied to organic aerosol data measured using an aerosol mass spectrometer, a twin-site study, and elemental tracer methods, and then assigning PM mass concentrations to 13 emission sources. The major contributing emission sources for PM0.1 were automobile exhaust (30%) and coal combustion, possibly related to integrated steelworks (24%), in winter, and fuel combustion (39%) and automobile exhaust (11%) in summer. Despite conducting measurements at one of the most heavily polluted traffic intersections in Japan, more than half of the anthropogenic primary emissions of PM0.1 and PM2.5 measured at the intersection were derived from sources other than automobile exhaust emissions. Since PM emissions from stationary-source flue gas has historically been less well regulated than automobile exhaust emissions, further mitigation measures need to be implemented in order to reduce atmospheric PM levels.