Development of an exposure-based strategy for attaining U.S. particulate standards

This paper proposes that a fundamental principle for designing optimal strategies to attain the new U.S. particulate standards be minimization of exposure to, and inhaled dosage of, that portion of ambient particulate matter (PM) believed to be of health concern. Minimization of exposure is equivalent to maximization of human health risk reduction. A prototype model, PMEX, is described to illustrate implementation of such a design principle. PMEX calculates PM exposure and inhaled dosage as figures-of-merit for control strategy optimization, accounting for activity pattern, indoor-outdoor differences, and geographical location. Results are presented for two hypothetical examples, Los Angeles, CA and Steubenville, OH. Inhaled dosage is apportioned among different classes of sources, under different assumptions about the relative potency of different PM categories. While preliminary, results demonstrate that conclusions about source class contribution based on inhaled dosage can be appreciably different than those based on ambient air measurements or emission inventories.