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.