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Abstract:
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Ambient particulate matter (PM) air pollution is currently regulated in the US by total mass concentration. Because PM total mass is a complex chemical mixture generated by natural and anthropogenic sources, identifying which sources of PM are most toxic can lead to more targeted regulation of PM. However, sources are not generally measured in ambient air and are frequently estimated from chemical constituent data using source apportionment models. Some source apportionment models apply mathematical constraints to facilitate source estimation (e.g. sources are orthogonal), and others incorporate prior information about sources of PM present in a community. When prior information is not available, it is unclear how to verify that estimated sources correspond to existing sources of PM in a community. Ad hoc methods are generally used to match estimated sources to existing sources, though other, validated approaches enable consistent identification of sources and are more reproducible. Approaches to match estimated sources to existing sources of PM are critical to conducting the regional and national-level epidemiologic studies necessary to update PM regulation.
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