Exposure to household air pollution over 10 years is related to asthma and lung function decline. [Respirology]

Abstract

Introduction/Aim. Clinical guidelines on obstructive lung disease contain few recommendations on household air pollution (HAP), although it is known to cause oxidative stress, which is associated with pathogenesis of obstructive lung disease. Associations between HAP and obstructive lung disease may be modified by Glutathione S-Transferase (GST) gene polymorphisms and home ventilation. We aimed to identify longitudinal HAP profiles associated with asthma risk and lung function decline in middle-aged adults and whether these associations were modified by GST gene variants and home ventilation. Methods. We used measurements of HAP exposures (emission sources for heating/cooking, mould, smoking) asthma, and housing characteristics collected for the Tasmanian Longitudinal Health Study (TAHS) at mean ages 43 and 53 years (n = 3314). Latent class analysis was used to characterize longitudinal exposure patterns. A sub group had data on lung function (n = 897) and GST polymorphisms (GSTM1, GSTT1 and GSTP1) (n = 928). Regression models assessed associations and interactions. Results. We identified seven longitudinal HAP profiles. Four of these ("wood heating", "all gas", "wood heating/smoking" and "wood heating/gas cooking") were associated with persistent asthma, greater lung function decline and greater bronchodilator reversibility (BDR) by age 53 years. Exposed participants with GSTP1 Ile/Ile and GSTM1 null genotypes were at higher risk of asthma or greater lung function decline compared to other genotypes. Home ventilation modified these adverse effects; participants not using cooking exhaust fans or living in newer, better sealed, buildings had increased risk of asthma. Conclusion. Longitudinal exposure to wood heating, gas cooking and heating, and tobacco smoke over 10 years increased the risk of persistent asthma, lung function decline and increased BDR. There was evidence of effect modification by GST genotypes and home ventilation. These findings inform the development of more comprehensive asthma/COPD public-health guidelines that include means of reducing HAP exposures.