Gender-specific association between household cooking oil fumes exposure and small airway dysfunction in China: a national cross-sectional study.

Household cooking oil fumes (COF) are a common indoor pollutant, but the degree of exposure and relationship with small airway dysfunction (SAD) remain unclear. Using data from a national chronic obstructive pulmonary disease survey (2019-2020) in China, here, we analyzed gender-specific COF exposure and its association with SAD. Exposure was categorized as direct or indirect based on cooking frequency and perceived COF. Among 62,627 participants, direct COF exposure was reported by 89.9% of women and 43.5% of men, whereas indirect exposure was more common in men (14.0%) than in women (1.9%). Multilevel logistic and linear regression analyses showed that direct exposure was associated with higher SAD risk (OR = 1.13, 95% CI: 1.03-1.24) and lower small airway function in women, with a stronger effect in those with obesity (OR = 1.39, P for interaction = 0.007). In men, indirect exposure was associated with higher SAD risk (OR = 1.14, 95% CI: 1.06-1.22) and similar functional decline. We also evaluated joint and additive interactions of COF with biomass use for cooking, PM2.5 exposure, and smoking. Synergistic effects were observed between indirect COF and biomass use (OR = 1.27, RERI = 0.27) in men. Combined exposure to COF and high PM2.5 or smoking amplified SAD risk in both genders. These findings indicate that household COF exposure is associated with a higher risk of SAD, with distinct gender-specific patterns. Based on the observed associations, greater public health efforts should be made to reduce COF exposure, especially among obese women and individuals with combined exposure to COF and other risk factors, such as the use of biomass for cooking, high PM2.5 exposure, or smoking.