GATA4 and chronic obstructive pulmonary disease: Sood et al. showed that WS exposure interacted with aberrant promoter methylation of the p16 or GATA4 genes, increasing the risk of COPD and lower FEV1 in smokers.20 Awji et al. found that WS enhances TS-induced inflammation in airway epithelial cells.29 The inflammatory pathways induced by biomass smoke/WS or TS could be different,16,19,30,31 and could interact in enhancing the negative effects of the combined exposure.