Though indoor air pollution (IAP) is associated with elevated lung cancer risk, an integrated measure is imperative to thoroughly investigate this association. The interplay between sex and IAP on lung cancer remains unclear. We conducted a population-based case-control study in Jiangsu Province, China, from 2003 to 2010, with 2871 lung cancer cases and 8019 controls. Exposures and covariates information were collected via in-person interviews using a standardized questionnaire. An integrated weighted risk score (WRS), accounting for the effect sizes of each source of IAP, was introduced. Unconditional logistic regression was employed to estimate adjusted odds ratios (aORs) and their 95% confidence intervals (CIs). Interactions between sex and IAP by tobacco smoking status were evaluated. Environmental tobacco smoking (ETS) (aOR = 1.54, 95% CI: 1.40, 1.69), poor ventilation (aOR = 1.18, 95% CI: 1.07, 1.30), and coal used for cooking (aOR = 1.27, 95% CI: 1.15, 1.41) were associated with lung cancer. Dose-response relationships between lung cancer and WRS were observed, with p for trend less than 0.001. aOR for individuals at the highest quartile of the WRS of IAP was 1.74 (95% CI: 1.52, 2.00) compared to the lowest quartile. The associations were more profound among never-smokers than ever-smokers. Females tended to be more vulnerable to IAP, and sex interacted with IAP beyond multiplicativity on the odds scale. IAP is associated with lung cancer, with a stronger impact among never-smokers. An interaction between IAP and sex was observed. These results underscore the importance of controlling IAP, especially ETS in order to reduce the risk of lung cancer.
Keywords: environmental tobacco smoking; indoor air pollution; lung cancer; sex; tobacco smoking.