Table 2.

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

Pollutant	Mean	90% CI	95% CI
SO2		0.82		0.57, 1.08		0.48, 1.15
NO2		0.62		0.43, 0.92		0.40, 0.98
CO		0.64		–0.10, 1.06		–0.20, 1.09
Units are 10 ppb for NO2 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 joint-pollutant analyses are based on data from 58 cities.