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

Abstract

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 PM(1), PM(2.5), PM(7), PM(10), 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/m(3), and PM(10) was 230 μg/m(3). PM levels in winter are strongly correlated with solid fuel usage for cooking, heating, and ventilators. PM(1) levels in cases are more than 3 times higher than that in controls. Every 10 μg/m(3) increase in PM(1) 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.

Figure 1

Indoor and outdoor PM Levels during summer and winter in non-smoking women. X-axis: Indoor or outdoor, by summer and winter. Y-axis: PM concentration (µg/m³). The colors were based on different size of PM.

Figure 2

PM₁ levels among female non-smoking cases and controls in winter. The comparison of PM1 levels in different rooms among cases and controls are showed in the figure. X-axis: cases and controls by different rooms. Y-axis: PM₁ concentration (µg/m³). “Star” represent p value <0.05

Figure 3

Associations between PM levels and indoor exposures among females. The figure shows whether indoor air pollution exposure is correlated with PM concentration in different size. X-axis: PM in different size by indoor exposures. Y-axis: PM₁ concentration (µg/m³). “Star” represent p value <0.05 “Diamond” represent p value<0.1