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Improvement in household stoves and risk of chronic obstructive pulmonary disease in Xuanwei, China: retrospective cohort study

BMJ 2005; 331 doi: (Published 03 November 2005) Cite this as: BMJ 2005;331:1050
  1. Robert S Chapman, lecturer1,
  2. Xingzhou He, professor2,
  3. Aaron E Blair, senior investigator3,
  4. Qing Lan (qingl{at}, staff scientist3
  1. 1 College of Public Health, Chulalongkorn University, Institute Building 3, 10th Floor, Soi Chulalongkorn 62, Phyathai Road, Patumwan, Bangkok 10330, Thailand
  2. 2 Institute of Environmental Health and Engineering, Chinese Academy of Preventive Medicine, 29 Nan Wei Road, Beijing 100050, China
  3. 3 Occupational and Environmental Epidemiology Branch, Division of Cancer Epidemiology and Genetics, National Cancer Institute, NIH, DHHS, MSC 7240, 6120 Executive Blvd, EPS 8111, Bethesda, MD 20892, USA
  1. Correspondence to: Q Lan
  • Accepted 19 August 2005


Objective To test whether improvement in household coal stoves affected the incidence of chronic obstructive pulmonary disease (COPD) in Xuanwei County, China.

Design Retrospective cohort study (follow-up 1976-92) comparing incidence of COPD between groups with and without chimneys.

Participants 20 453 people born into homes with unvented coal stoves;16 606 (81.2%) subsequently changed to stoves with chimneys.

Intervention Installation of a chimney in households in which unvented stoves had been used previously.

Results Installation of a chimney was associated with distinct reduction in the incidence of COPD. Compared with people who did not have chimneys, the Cox-modelled risk ratio (relative risk) was 0.58 (95% confidence interval 0.49 to 0.70, P < 0.001) in men and 0.75 (0.62 to 0.92, P = 0.005) in women. Modelled risk ratios were robust to different Cox model specifications. Relative risks decreased with time since stove improvement. In both sexes, the reduction in risk became unequivocal about 10 years after stove improvement.

Conclusions In Xuanwei, incidence of COPD decreased markedly after household coal stoves were improved.


  • Contributors XH and QL designed this study, managed data collection, and participated in data processing. RSC participated in data processing, conducted most of the analyses, and was primarily responsible for writing the paper. The analysis incorporated suggestions by AEB, XH, and QL. All authors contributed to draft manuscripts and the final version. RSC is the guarantor.

  • Funding Chinese Academy of Preventive Medicine, Beijing, China; Yunnan Province Antiepidemic Station, Kunming, China; US Environmental Protection Agency (contract No 5D2290NFFX); and intramural research programme of the NIH, National Cancer Institute. This report does not necessarily reflect US Environmental Protection Agency policy or Depart-ment of Health and Human Services policy. Mention of commercial products does not constitute endorsement for use.

  • Competing interests None declared.

  • Ethical approval Institutional review board of the Chinese Academy of Preventive Medicine.

  • Accepted 19 August 2005
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