Indoor air pollution and risk of lung cancer among Chinese female non-smokers

Purpose: To investigate indoor particulate matter (PM) level and various indoor air pollution exposure, and to examine their relationships with risk of lung cancer in an urban Chinese population, with a focus on non-smoking women. Methods: We conducted a case-control study in Taiyuan, China, consisting of 399 lung cancer cases and 466 controls, of which 164 cases and 218 controls were female non-smokers. Indoor PM concentrations, including PM₁, PM _2.5, PM₇, PM₁₀, and TSP, were measured using a particle mass monitor. Unconditional logistic regression models were used to calculate odds ratios (ORs) and 95 % confidence intervals after adjusting for age, education, annual income, and smoking. Results: Among non-smoking women, lung cancer was strongly associated with multiple sources of indoor air pollution 10 years ago, including heavy exposure to environmental tobacco smoke at work (aOR = 3.65), high frequency of cooking (aOR = 3.30), and solid fuel usage for cooking (aOR = 4.08) and heating (aOR_{coal stove} = 2.00). Housing characteristics related to poor ventilation, including single-story, less window area, no separate kitchen, no ventilator, and rarely having windows open, are associated with lung cancer. Indoor medium PM_2.5 concentration was 68 μg/m³, and PM₁₀ was 230 μg/m³. PM levels in winter are strongly correlated with solid fuel usage for cooking, heating, and ventilators. PM₁ levels in cases are more than 3 times higher than that in controls. Every 10 μg/m³ increase in PM₁ is associated with 45 % increased risk of lung cancer. Conclusions: Indoor air pollution plays an important role in the development of lung cancer among non-smoking Chinese women.