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moking is one of the major factors that affects lung function. Because more than 60% of Chinese men are active smokers, the current study included both smoking and non-smoking subjects to
increase generalizability of the study and allow the assessments of potential effect modification by smoking. It has been reported that peak expiratory flow only changes among smokers, not non- smokers (Linares et al., 2010). However our finding provides evidence that peak expiratory flow responds to air pollution changes in both smokers and non-smokers. Peak expiratory flow was higher in nonsmokers than that in smokers among both males and females (fig. 1). Although trends are similar in subgroups by gender, smoking, and age, when air pollution levels decreased during the game, peak expiratory flow level increased more (around 17%) in non-smokers, female and younger individuals than that in smokers, male and older individuals (around 12%). For those smokers, males and older individuals, lung function could have been impaired to a certain degree, such that their response to improved air quality was muted and the extent of the improve- ment in lung function was smaller, although only a very slight difference in peak expiratory flow percentage change was identi- fied between two groups (smokers versus non-smokers