Biomass fuels are the probable risk factor for chronic obstructive pulmonary disease in rural South China

Background: There is increasing evidence for a possible association between chronic obstructive pulmonary disease (COPD) and the use of biomass fuels for cooking and heating in developing countries. Data on the prevalence of COPD and objective measurements of indoor pollution from biomass fuel have not been widely available from China. A study was undertaken to investigate the prevalence of COPD in two study communities in Guangdong province in China and to measure the association between COPD and indoor biomass fuel air pollution. Methods: A cluster disproportional random sampling survey was performed in populations aged over 40 years in urban (Liwang) and rural (Yunyan) areas in Guangdong, China. Spirometry was performed in all subjects and a post-bronchodilator ratio of the forced expiratory volume in 1 s to forced vital capacity of < 0.70 was defined as COPD. Measurements of indoor and outdoor air pollutants were also performed in a random sample of households. Results: The overall prevalence of COPD in the two areas ( Liwang and Yunyan) was 9.4%. The prevalence of COPD in both the whole population and a subpopulation of non-smoking women in rural Yunyan was significantly higher than in urban Liwang (12.0% vs 7.4%, and 7.2% vs 2.5%, respectively). The use of biomass fuel was higher in rural Yunyan than in urban Liwang (88.1% vs 0.7%). Univariate analysis showed a significant association between COPD and exposure to biomass fuel for cooking. Multivariate analysis showed a positive association between COPD and urban/rural area (surrogate for fuel type and local exhaust ventilation in kitchen) after adjustment for sex, age group, body mass index, education, occupational exposure, respiratory disease in family, smoking status, life quality and cough in childhood; similar results were found in non-smoking women. Pollutants measurements showed that concentrations of carbon monoxide, particulate matter with an aerodynamic diameter (10 mm, sulphur dioxide and nitrogen dioxide in the kitchen during biomass fuel combustion were significantly higher than those during LPG combustion. Conclusions: Indoor pollutants from biomass fuels may be an important risk factor for COPD in rural South China.