Prevalence of persistent cough and phlegm in young adults in relation to long-term ambient sulfur oxide exposure.

In early 1976, a survey of persistent cough and phlegm (PCP) prevalence was conducted in 5,623 young adults in 4 Utah communities. Over the previous 5 years, community-specific mean sulfur dioxide levels had been 11, 18, 36, and 115 micrograms/m3. Corresponding mean suspended sulfate levels had been 5, 7, 8, and 14 micrograms/m3. No intercommunity exposure gradient of total suspended particulates or suspended nitrates was observed. In nonsmoking mothers, PCP prevalence was 4.2% in the high-exposure community and approximately 2.0% in all other communities. In smoking mothers, PCP prevalence was 21.8% in the high-exposure community and approximately 15.0% elsewhere. In nonsmoking fathers, PCP prevalence was 8.0% in the high-exposure community and averaged 3.0% elsewhere. In smoking fathers, PCP prevalence was less strongly associated with ambient sulfur oxide exposure. Intercommunity prevalence differences in smoking and nonsmoking mothers, and in nonsmoking fathers, were significant at alpha = 0.05. A categorical logistic regression model, testing simultaneously for effects of community and several covariates on PCP prevalence, yielded similar results. The results of this survey were similar to those of a similar survey conducted in Utah in 1970 and to those of other surveys. These results disclose an association of PCP prevalence with ambient sulfur oxide exposure, stronger in mothers than in fathers, stronger in nonsmokers and ex-smokers than in smokers, and stronger in 1970 than 1976.