Table 6.

ER of mortality associated with a 10-μg/m³ increase in lag 1–2 day O₃ concentrations by O₃ exposure period,a under single- and two-pollutant models, using city-merged data [percent (95% CI)].

Mortality	Method	Peak period	Nonpeak period
Total		Single-pollutant model		0.65 (0.27, 1.02)		0.92 (0.69, 1.16)
		Adjusted by PM10		0.77 (0.32, 1.22)		0.64 (0.39, 0.89)
Cardiovascular		Single-pollutant model		0.96 (0.35, 1.58)		1.06 (0.69, 1.44)
		Adjusted by PM10		1.33 (0.59, 2.08)		0.67 (0.27, 1.07)
Respiratory		Single-pollutant model		0.24 (–0.63, 1.13)		2.00 (1.47, 2.53)*
		Adjusted by PM10		0.08 (–0.98, 1.16)		1.62 (1.05, 2.20)*
aPeak period (September through November) with 8-hr mean O3 of 117.4 μg/m3 and nonpeak period (December through August) with 8-hr mean O3 of 66.9 μg/m3. Other covariates controlled for were the same as those in Table 4. *Significantly different from the peak period (p < 0.01).