Cigarette smoking and ozone-associated emergency department use for asthmaby adults in New York City

The association between ambient ozone (O-3) and hospital use for asthma in children and adults is well documented. The question remains of whether the re are susceptible subpopulations of asthmatic individuals who are particul arly vulnerable to high O-3 levels. Because tobacco use was prevalent in ou r cohort of inner-city adult asthmatic individuals (n = 1,216) in New York City (NYC), we investigated whether cigarette smoking was an effect modifie r for asthma morbidity. We examined the relationship between personal tobac co use and O-3-associated emergency department (ED) use for asthma in publi c hospitals in NYC. Three subpopulations were defined: never smokers (0 pac k-yr), heavy smokers (greater than or equal to 13 pack-yr) and light smoker s (<13 pack-yr). Time-series regression analysis of ED use for asthma and d aily O-3 levels was done while controlling for temperature, seasonal/long-t erm trends, and day-of-week effects. Heavy smokers displayed an increased r elative risk (RR) of ED visits for asthma in response to increases in 2-d l agged O-3 levels (RR per 50 ppb O-3 = 1.72; 95% confidence interval: 1.13 t o 2.62). Logistic regression analysis confirmed that heavy cigarette use wa s a predictor of ED use for asthma following days with high O-3 levels. Alt hough adverse health effects of ambient O-3 have also been documented in as thma populations not using cigarettes (e.g., children), our results suggest that in adult asthmatic individuals, heavy personal tobacco use may be an effect modifier for (O)(3)-associated morbidity.