Chronic obstructive pulmonary disease (COPD) has high disability and fatality rates and imposes great economic and social burdens.The prevalence of COPD among individuals over 40 years old is estimated at 13.7% in China. 1 Factors that influence COPD development and progression are extremely complex, and smoking is not the only factor. Almost three billion people worldwide use wood as the main source of energy for cooking, heating and other household needs. Indoor biomass smoke exposure increases the risk of COPD, and accounts for 50% of deaths in patients with COPD in developing countries, 2 and increases in COPD hospitalization. [3][4][5][6][7] Alterations in cooking fuels and kitchen ventilation can halt the associated decline in forced expiratory volume in 1 s (FEV 1.0 ). 8 Although the pathologic features of COPD induced by biomass ambient particulate matter (PM) are less severe than those of COPD induced by smoking, 9 their hazards should not be ignored. However, the molecular pathway of pathological damage