Parameters

Lag-time assumptions

5-year lag structure assumed for PM-related premature deaths with 25% in years 1 and 2 and 16.7% in years 3, 4, and 5

Quantification of uncertainty

1. Calculated 5th and 95th percentiles that reflected within-study variance and across-study variability in both the health effects estimation and the economic valuation steps;

2. Provided alternative calculations for key assumptions;

3. Conducted sensitivity analyses

Study populations evaluated for health outcomes

Majority of benefits estimated for adult populations. PM mortality estimated for population 30 yr and older. Some hospital admissions studies use entire population; others use the population over 65 yr

aMany other health outcomes were listed as unquantified for the listed pollutants. A few health outcomes were quantified but were not monetized because they were included in another benefits category.

post-CAAA condition in which all rules stemming from passage of the 1990 CAAA are implemented. However, the post-CAAA condition does not include the recent regulations described in this chapter (PM and ozone NAAQS, Tier 2 emissions standards, and HD engine and diesel-fuel standards). EPA noted that the recent regulations use the prospective post-CAAA scenario as the baseline; therefore, the benefits estimates in those analyses are considered incremental to those estimated for the prospective analysis (EPA 1999b).

Benefits are analyzed in the aggregate for Titles I-V, and annual estimates of benefits and costs are presented for the years 2000 and 2010. The present value of benefits and costs over the period 1990 to 2010 are also calculated. Categories of benefits estimated include health, visibility, agricultural, and ecological benefits. The process used to calculate the benefits is similar to that used to evaluate benefits for the Tier 2 and the HD engine and diesel-fuel rules.

First, the changes in emissions of PM (PM2.5 and PM10), SO2, NOx, VOCs, and CO were estimated for the base-year 1990 and for the pre- and post-CAAA scenarios in 2000 and 2010. The changes in emissions are primarily associated with Titles I, II, and IV. The impacts of Title III on HAP emissions were not calculated; consequently, the health benefits



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