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Epidemiological evidence has suggested that ambient air pollution is an increasingly important risk factor for respiratory diseases without assessing its influence on laryngeal neoplasms incidence in China. We constructed two-way fixed effect models and Poisson regression models to explore the effects of ambient air pollutants including nitrogen dioxide (NO 2 ), sulfur dioxide (SO 2 ), and particulate matter less than or equal to 10 μm in aerodynamic diameter (PM 10 ) on incidence of laryngeal neoplasms in twelve major cities in China over the period 2006-2013. The annual average concentration for PM 10 , SO 2 , and NO 2 was 107.22 μg/m 3 , 44.07 μg/m 3 , and 46.71 μg/m 3 with standard deviations of 24.84 μg/m 3 , 13.68 μg/m 3 , and 9.19 μg/m 3 , respectively. We observed that ambient air pollutants were significantly positively correlated with the incidence of laryngeal neoplasms, especially for NO 2 . The relative risks of overall incidence of laryngeal neoplasms in the current period were 1.20, 1.04, and 1.00 for NO 2 , SO 2 , and PM 10 , with 95% confidence intervals (CIs) of 1.01-1.43, 0.93-1.16, and 0.96-1.05, respectively. Moreover, this deleterious impact was stronger in the male than in the female, likely due to genetic predisposition caused by longer exposure to more serious air pollution for men. Our findings complement the epidemiological evidence of laryngeal neoplasms due to ambient air pollution and reinforce the necessity of policy efforts to control the noxious air pollution emissions.

Large cities in China are experiencing severe ambient air pollution. Although China accounts for more than 45% of new cases of nasopharyngeal carcinoma worldwide in 2018, few studies have examined the association between ambient air pollution and the high nasopharyngeal carcinoma (NPC) incidence in China. Thus, we aim to investigate whether exposure to ambient air pollution (including nitrogen dioxide, sulfur dioxide, and PM 10 ) would significantly affect NPC incidence in large Chinese cities. We collected panel data of ten Chinese provincial cities about local NPC incidence, air pollution level, meteorology, and city profiles during 2006 to 2013 to construct a two-way fixed-effects model to explore the association between ambient air pollution and NPC incidence, as well as possible regional and gender differences behind the association. We found that NO 2 had the strongest association with NPC incidence, and the relative risks were 2.2995 (95% CI, 1.2567-4.2075) for males and 1.3010 (95% CI, 0.8212-2.0620) for females, respectively. Under cumulative exposure, it was still NO 2 that had the strongest association with NPC incidence, with a relative risk of 1.8836 (95% CI, 1.2416-2.8577), compared to 1.0857 (95% CI, 0.9474-1.2450) and 1.0547 (95% CI, 0.8790-1.2663) for SO 2 and PM 10 , respectively. In addition, males were found more sensitive to ambient air pollution than females. We also found that southern Chinese cities were more sensitive to NO 2 than northern cities, which might be related to a higher humidity there. Our study reveals that exposure to ambient air pollutants like SO 2 , PM 10 , and particularly NO 2 , is significantly positively associated with NPC incidence in China.