Are long-term Household Air Pollutions (HAPs) associated with asthma and lung function decline in middle-aged adults, and whether these associations were modified by GST gene variants, ventilation and atopy.Prospective data on HAPs (heating, cooking, mould, smoking) and asthma were collected in the Tasmanian Longitudinal Health Study (TAHS) at mean ages 43 and 53 years (n=3314). Subsamples had data on lung function (n=897) and GST gene polymorphisms (n=928). Latent class analysis was used to characterise longitudinal patterns of exposure. Regression models assessed associations and interactions.We identified seven longitudinal HAP profiles. Of these, 3 were associated with persistent asthma, greater lung function decline and %reversibility by age 53 years, compared to "least exposed" profile, for who used reverse cycle air conditioning, electric cooking and without smoking. "All gas"(OR:2.64, 95%CI 1.22-5.70), "wood heating/smoking" (2.71, 1.21-6.05) and "wood heating/gas cooking" (2.60, 1.11-6.11) were associated with persistent asthma, greater lung function decline and %reversibility. Participants with GSTP1 Ile/Ile genotypes were at a higher risk of asthma or greater lung function decline when exposed compared to other genotypes. Exhaust fan use and opening windows frequently could reduce the adverse effects of HAP produced by combustion heating and cooking on current asthma presumably through increasing ventilation.Exposures to wood heating, gas cooking and heating, and tobacco smoke over 10 years increased the risks of persistent asthma, lung function decline and %reversibility, with evidence of interaction by GST genes and ventilation.