Table 3.

Estimated mean percent change in daily mortality associated with a unit increase in pollutant concentration on the previous day, two-pollutant model.

Pollutant	Mean	90% CI	95% CI
PM10		0.29		0.16, 0.42		0.13, 0.45
CO		1.23		0.68, 1.64		0.55, 1.70
PM10		0.20		0.07, 0.33		0.03, 0.36
NO2		0.94		0.66, 1.20		0.60, 1.26
PM10		0.33		0.23, 0.45		0.19, 0.46
SO2		1.33		0.66, 1.85		0.38, 1.97
PM10		0.39		0.29, 0.49		0.25, 0.51
O3		0.22		–0.0008, 0.43		–0.05, 0.48
Units are 10 µg/m3 for PM10; 10 ppb for NO2, O3, and SO2; and 1 ppm for CO. Temperature and relative humidity on the previous day are controlled using 6 df natural splines. Time trends are controlled using 100 df natural splines, and day of week is controlled as a categorical variable. These two-pollutant analyses are based on 92 cities for PM10 and CO, 72 cities for PM10 and NO2, 83 cities for PM10 and SO2, 95 cities for PM10 and O3.