During the air pollution episode, higher heart rates were observed in men and women (table 2). Adjustment for cardiovascular risk factors reduced the effect estimates for the episode. The heart rate was associated with cardiovascular risk factors such as body mass index, serum cholesterol, blood pressure, and smoking. Women had higher heart rates than did men, and several cardiovascular risk factors had different impacts on the heart rates in men and women. Regular leisure time activity reduced the heart rates as reported earlier (21). An indicator for cardiovascular disease medication was associated with a reduced heart rate, but it did not confound the association between heart rate and the air pollution. Further adjustment for the meteorologic conditions attenuated the estimates that were not statistically significant themselves.