Researchers from the Harvard School of Public Health (HSPH) have concluded that smoking, secondhand smoke, and inhaling the smoke from biomass fuels like wood, animal dung and charcoal all raise the risk of contracting tuberculosis (TB) among residents of developing countries.

"The evidence suggests that, when compared to nonsmokers, smokers have about double the risk of tuberculosis. The implication for global health is critical," said Megan Murray, associate professor of epidemiology at HSPH. "Since tobacco smoking has increased in developing countries where TB is prevalent, a considerable portion of the global burden of TB may be attributed to tobacco. Importantly, this also implies that smoking cessation might provide benefits for global TB control in addition to those for chronic diseases."

The Harvard researchers reviewed data in a total of 1,297 papers on smoking, TB, and indoor air pollution conducted from 1950 to 2006. They found that smokers have a higher risk than nonsmokers of contracting TB, having active TB disease, and dying of the disease. An association between secondhand smoke and TB risk also was found, although this conclusion was based on a far smaller group of studies.

The study appears online on January 16, 2007, in the journal PLoS Medicine.