Chinese chimneys slash lung cancer risk

People who replace rudimentary domestic hearths with well-ventilated stoves enjoy both less-smoky homes and a dramatic reduction in their risk of developing lung cancer, according to a study conducted in rural China. The finding suggests that improvements to the cooking equipment used in poor countries could lessen lung cancer incidence.

Extremely smoky dwellings are common in the world’s underdeveloped regions, such as China’s damp and hilly Xuanwei County, where open fire pits traditionally provided heat for cooking and warmth. With support from the Chinese government, the majority of Xuanwei’s residents have in recent decades installed stoves with chimneys that funnel smoke away from living spaces.

To determine whether the switch affected lung cancer rates, Qing Lan of the Chinese Academy of Preventive Medicine in Beijing and her colleagues there and at the U.S. Environmental Protection Agency in Research Triangle Park, N.C., gathered data on 21,232 people who lived in Xuanwei in 1976.

Between 1976 and 1992, 1,384 people in the study developed lung cancer. Men whose homes had chimneys were only 59 percent as likely to develop lung cancer each year as men living with unimproved ventilation were. For women, lung cancer risk fell slightly lower, the researchers report in the June 5 Journal of the National Cancer Institute.

Indoor air sampling established that vented stoves generated substantially less soot and other airborne particulate matter than unimproved hearths did.

Women may reap somewhat greater health benefits than men do from vented stoves because they handle most of the cooking, says Robert S. Chapman, an EPA epidemiologist who worked on the study. Chapman notes that for men who did cook, each year in which they cooked appears to contribute more to their lung cancer risk than each year in which they smoked.

While vented stoves may be lowering the risk of lung cancer in Xuanwei, indoor air pollution from domestic cooking fires nevertheless poses a significant health problem elsewhere in the world, says Jonathan M. Samet of the Johns Hopkins School of Public Health in Baltimore.