Health benefits from ozone reduction in the United States Environment (version 2.11; R Project for Statistical Computing, Vienna, Austria). Results Air monitor data. A total of 1,170, 1,168, and 1,183 AQS ozone air monitors fit the data completeness criteria for 2005, 2006, and 2007, respectively. Mean values for daily 8-hr maximum ozone warm-season measurements ranged from 44.9 to 45.5 ppb (Table 2). From visual observation, the highest regional concentrations appeared to be in noncoastal southern (53.6 ppb) and central (52.8 ppb) portions of California, near Salt Lake City (55.6 ppb), southern Arizona (51.7 ppb), and portions of western North Carolina (55.1 ppb). Moderately elevated concentra- tions were observed throughout the Midwest, South, the Northeast corridor, and Texas. Interpolated ozone rollbacks. Estimates of ozone reduction following the proposed regu- latory standards are presented for the United States (Figure 1). Considerable temporal varia- tion within locations could be observed by year. For 2006, the estimated mean ozone reduction is 0.97 ppb at the 75-ppb stan- dard, 2.06 ppb at the 70-ppb standard, and 5.73 ppb at the 60-ppb standard. The maxi- mum estimated ozone reduction for 2006 is 23.63 ppb under a 60-ppb standard in south- ern California. Values estimated using 2005 and 2007 data are slightly different, but spatial patterns were generally consistent across years. There is substantial geographic variation, with the highest estimated reductions occurring in southern California, the Midwest, and por- tions of the Northeast corridor. Nationwide mortality and morbidity health impacts. Annual avoided premature mortalities were estimated for the United States (Table 3). Under the current 75-ppb standard, the greatest reductions in all-cause mortalities were estimated for 2005, ranging from 2,480 (90% CI: 1,830, 3,130) using the C-R function derived by Levy et al. (2005) to 1,760 (90% CI: 990, 2,530) using the Bell et al. (2005) estimate. We estimated fewer avoided deaths in 2006 (640 cardiopulmonary mortalities at the current standard), the year with the smallest mean ozone concentration, compared with 2005 and 2007 (800 and 700 avoided cardiopulmonary-related mortalities at the current standard). Estimates of reduc- tions in nonaccidental deaths were smallest when based on the C-R function derived from Bell et al. (2004), and largest based on the C-R function from Ito et al. (2005) (e.g., 900 fewer deaths (90% CI: 400, 1,400) compared with 2,780 (90% CI: 1,420, 5,000) in 2005 under the 70-ppb standard, respectively). We estimated that there would be almost three times as many respiratory mortalities (1,970) avoided than cardiopulmonary-related deaths (700) at the 75-ppb standard for 2007 with similar trends for other years. As expected, esti- mated numbers of avoided health outcomes increased as proposed regulatory levels became more stringent. For example, using the C-R function from Levy et al (2005) and data for 2005, we estimated 2,480 avoided deaths if the current 75-ppb standard had been met, compared with 4,130 avoided deaths under a 70-ppb standard (a 67% increase in avoided deaths) and 7,990 avoided deaths (a 222% increase) under a 60-ppb standard. This gen- eral trend holds true across data years and alternative risk estimates. Avoided morbidities were variable with large numbers of school-loss days and acute respiratory symptoms (Table 4). Across the data years, acute respiratory symptoms would have been reduced by 3–3.5 million cases/ year if the current 75-ppb standard had been achieved, and 10.3–11 million acute respi- ratory symptom events prevented under a 60-ppb standard, representing a 300% increase in avoided outcomes. In addition, Table 3. Estimates of nationwide prevented mortalities (mean and 90% CI) after meeting the current and proposed ozone regulatory standards (2005–2007).a,b Health end point Nonaccidental mortality Bell et al. 2004 Ito et al. 2005 Schwartz 2005 2005 540 (240, 840) 1,670 (850, 3,010) 820 (350, 1,300) 75-ppb standard 2006 70-ppb standard 2006 2007 2005 2007 2005 60-ppb standard 2006 2007 430 470 (190, 670) (207, 730) 1,340 1,460 (680, 2,400) (740, 2,630) 660 720 (280, 1,040) (300, 1,130) 900 750 822 (400, 1,400) (330, 1,160) (360, 1,280) 2,780 2,320 2,550 (1,420, 5,000) (1,180, 4,170) (1,300, 4,590) 1,370 1,140 1,250 (580, 2,150) (480, 1,800) (530, 1,970) 1,740 1,590 1,690 (770, 2,710) (700, 2,480) (750, 2,640) 5,380 4,930 5,250 (2,750, 9,670) (2,520, 8,860) (2,680, 9,430) 2,640 2,420 2,580 (1,120, 4,170) (1,020, 3,820) (1,090, 4,070) All-cause mortality Bell et al. 2005 1,760 1,410 1,540 2,930 2,450 2,690 5,680 5,210 5,540 (990, 2,530) (790, 2,030) (860, 2,210) (1,650, 4,210) (1,380, 3,520) (1,510, 3,860) (3,190, 8,160) (2,930, 7,490) (3,110, 7,950) Levy et al. 2005 2,480 1,990 2,160 4,130 3,450 3,780 7,990 7,330 7,790 (1,830, 3,130) (1,470, 2,510) (1,600, 2,730) (3,040, 5,210) (2,550, 4,360) (2,790, 4,780) (5,900, 10,100) (5,410, 9,250) (5,750, 9,830) Cardiopulmonary mortality 800 640 700 1,320 1,110 1,210 2,550 2,340 2,490 (380, 1,210) (310, 980) (330, 1,060) (630, 2,010) (530, 1,680) (580, 1,850) (1,220, 3,880) (1,120, 3,560) (1,190, 3,790) Respiratory mortality 2,230 1,790 1,970 3,730 3,110 3,440 7,210 6,620 7,060 (1,000, 3,450) (800, 2,770) (880, 3,050) (1,670, 5,770) (1,390, 4,810) (1,540, 5,320) (3,250, 11,100) (2,980, 10,200) (3,180, 10,900) aReferences for morbidity C-R estimates are provided in Table 1. bPopulation sizes used to derive these estimates are shown in Supplemental Material, Table S1 (http://dx.doi. org/10.1289/ehp.1104851). Table 4. Estimates of nationwide prevented morbidities (mean and 90% CI) after meeting the current and proposed ozone regulatory standards (2005–2007).a,b 75-ppb standard 70-ppb standard 60-ppb standard Health end point 2005 2006 2007 2005 2006 2007 2005 2006 2007 Acute respiratory symptoms 3,567,000 3,016,000 3,070,000 5,834,000 5,034,000 5,273,000 11,086,000 10,305,000 10,655,000 (1,821,000, (1,541,000, (1,567,000, (2,983,000, (2,574,000, (2,695,000, (5,688,000, (5,285,000, (546,400, 5,304,000) 4,482,000) 4,566,000) 8,666,000) 7,477,000) 7,835,000) 16,426,000) 15,274,000) 15,795,000) ED visits (respiratory) 1,800 1,460 1,500 2,920 2,450 2,590 5,570 5,070 5,260 (0, 4,030) (0, 3,250) (0, 3,350) (1, 6,520) (1, 5,450) (1, 5,740) (1, 12,600) (1, 11,400) (1, 1,1800) Hospital admissions 1,310 1,000 1,150 2,220 1,790 2,040 4,280 3,810 4,150 (respiratory) (330, 2,510) (250, 2,000) (300, 2,200) (570, 4,260) (440, 3,500) (530, 3,900) (1,110, 8,230) (960, 7,460) (1,080, 7,960) School-loss days 1,241,000 1,051,000 1,036,000 2,022,000 1,740,000 1,775,000 3,841,000 3,540,500 3,591,000 (553,000, (468,000, (461,000, (901,000, (775,000, (791,000, (1,716,000, (1,581,600, (1,604,000, 1,999,000) 1,693,000) 1,667,000) 3,259,000) 2,805,000) 28,610,000) 6,209,000) 5,721,200) 5,802,000) aReferences for morbidity C-R estimates are provided in Table 1. bPopulation sizes used to derive these estimates are provided in Supplemental Material, Table S1 (http://dx.doi. org/10.1289/ehp.1104851). Environmental Health Perspectives • volume 120 | number 10 | October 2012 1407