Association of indoor air pollution from coal combustion with influenza-like illness in housewives.

An association of influenza-like illness (ILI) with outdoor air pollution has been reported. However, the effect of indoor air pollution on ILI was rarely investigated. We aimed to determine an association of indoor air pollution from coal combustion (IAPCC) and lifestyle with ILI risk in housewives, and the modification effect of phase II metabolic enzyme genes. We recruited 403 housewives for a cross-sectional study in Shanxi Province, China, including 135 with ILI frequency (≥1 time per year in the past ten years) as the case group and 268 with ILI frequency (<1 times per year) as the control group. Information on their energy usage characteristics and lifestyle was collected by questionnaires, as well as the single nucleotide polymorphisms (SNPs) of epoxide hydrolase 1 (rs1051740 and rs2234922), N-acetyltransferase 2 (rs1041983), and glutathione S-transferase (rs1695). We used exposure index to indicate the level of IAPCC among housewives. Our results revealed that the exposure index was positively correlated with ILI frequency. A significant dose-response trend between the exposure index and ILI risk was found with or without adjusting for confounders. Cooking frequency in kitchen with coal as primary fuel and ventilation frequency in the living room or bedroom with a coal-fueled stove for heating during the heating season were two important risk factors to affect ILI frequency. Only rs1051740 was found to be associated with exposure index, whereas it didn't have interaction effect with exposure index on ILI frequency. In conclusion, IAPCC and SNPs of rs1051740 were both associated with ILI frequency.