county in the contiguous United States). Each type of exposure is computed separately for each pollutant. The sources for each of these inventories are documented in Muller and Mendelsohn (2006).

In the next stage of the APEEP model, peer-reviewed concentration-response functions are used to translate exposures into the number of physical effects, including premature mortalities, cases of illness, reduced timber and crops yields, enhanced depreciation of anthropogenic materials, reduced visibility, and recreation usage. The studies that provide the concentration-response functions related to human health impacts are listed in Table C-1.

The final stage of the APEEP model attributes a dollar value to each of these physical effects. For effects on goods and services traded in markets (decreased crop yields, for example), APEEP multiplies the change in output due to exposures to air pollution times the market price. For nonmarket goods and services, APEEP uses valuation estimates from the nonmarket valuation literature in economics. APEEP values premature mortality risks using the value of a statistical life (VSL) approach (Viscusi and Aldy 2003). APEEP uses EPA’s preferred VSL, which is equivalent to approximately $6 million (year 2000 real U.S. dollars). APEEP provides the option of using a VSL estimate of approximately $2 million from Mrozek and Taylor (2002) as an alternative to the EPA’s VSL. The values attributed to chronic illnesses, such as bronchitis and asthma, are also derived from the nonmarket valuation literature. Acute illnesses are valued with cost of illness estimates. Each of the values applied to human health effects in APEEP are shown in Table C-3.