Berman et al. we estimate that > 1 million school-loss days would have been avoided if the current stan- dard had been met, which highlights the impact of ozone on younger individuals. The large confidence intervals for estimated mor- bidity counts are partially driven by the pool- ing of multiple C-R functions. Results from sensitivity analyses dem- onstrated that reducing the assumed non- anthropogenic background ozone level (i.e., the policy relevant background level) from 40 to 20 ppb would increase estimated num- bers of avoided nonaccidental deaths by about 10% nationally (data not shown). Estimated numbers of avoided deaths were approxi- mately 66% lower when we used a peak shav- ing approach to estimate reductions in ozone levels compared to the default quadratic roll- back (data not shown). Because peak shaving 75 75 Atlanta 70 Detroit 70 New York 60 60 u o 10 c s t n y t i l a t r o e r u t a m m e rp 100 d e id 80 o A 60 v 35 30 25 20 15 10 5 0 30 25 20 15 5 0 40 20 0 4 3 2 1 0 ehp.1104851). 1408 20 15 10 5 0 20 15 10 5 0 50 40 30 20 10 0 4 3 2 1 0 75 75 75 Boston 70 Houston 70 Philadelphia 70 Seattle 60 60 60 assumes that ozone levels are only reduced at times and locations when air monitors indicate levels above the standard, it does not provide a realistic representation of emissions control policies (Rizzo 2005). Estimated reductions in nonaccidental deaths assuming reductions in ozone over the entire year were very similar to estimates based on the warm season only, e.g., 1,690 deaths avoided (90% CI: 745, 2,634) compared with 1,694 (90% CI: 747, 2,639) for the warm season using the Bell et al. (2004) risk estimate (data not shown). Avoided nonaccidental mortality by MSA. Estimated numbers of avoided nonaccidental deaths for 15 MSAs suggested both geographic and temporal differences in ozone-related health effects (Figure 2). We calculated the most avoided deaths for New York and Los Angeles, which had the largest populations of the MSAs evaluated [for the MSA popula- tion sizes, see Supplemental Material Table S2 (http://dx.doi.org/10.1289/ehp.1104851)]. However, annual differences in MSA esti- mates are also related to spatial variations in the ozone concentrations observed across our air quality years (Figure 1). For example, Miami, which had the sixth largest popula- tion, had the third smallest estimate in reduced deaths, whereas estimated avoided deaths for Riverside (California), which had the 13th largest population, were compara- ble to estimates for Philadelphia, the fourth largest MSA. Temporal patterns of esti- mated effects also varied among MSAs. For example, we estimated twice as many deaths avoided in Seattle, Miami, and San Francisco during 2006 compared with 2005 or 2007, but a 50% decrease in premature mortality Dallas 70 Miami 70 Riverside 75 75 75 Year 2007 2006 2005 60 60 50 40 30 20 10 0 60 50 40 30 20 10 0 25 20 15 10 5 0 30 25 20 15 10 5 0 75 75 Chicago 70 Los Angeles 70 Phoenix 60 60 40 30 20 10 0 8 6 4 2 0 50 40 30 20 10 0 75 70 60 San Fransisco 75 70 60 Washington, DC 70 60 75 70 60 75 70 60 75 70 60 Ozone rollback levels (ppb) Figure 2. Estimated numbers of avoided nonaccidental deaths in 15 MSAs following regulatory attainments of 75, 70, and 60 ppb according to year (2005–2007) [estimated using national C-R functions from Bell et al. (2004)]. MSA population sizes are provided in Supplemental Material, Table S2 (http://dx.doi.org/10.1289/ ovlume 120 | number 10 | October 2012 • Environmental Health Perspectives