An estimated two billion people in the developing world heat and cook with a biomass fuel such as wood, but the practice exposes people — especially women — to large doses of small-particle air pollution, which can cause premature death and lung disease. Jill Baumgartner, from the University of Wisconsin/Madison (Wisconsin, USA), and colleagues now link indoor air pollution with increased blood pressure among older women. In a remote area of Yunnan Province, China, 280 women in an ethnic minority called the Naxi, who live in compounds including a central, free-standing kitchen that often has both a stove and a fire pit, wore a portable device that sampled the air they were breathing for 24 hours. By correlating exposure over 24 hours with blood pressure, the team associated higher levels of indoor air pollution with a significantly higher blood pressure among women aged 50 and over. Small-particle pollution raises blood pressure over the short term by stimulating the nervous system to constrict blood vessels. In the long term, the particles can cause oxidative stress, which likewise raises blood pressure. In that other studies have shown that improved stoves or cleaner fuels can cut indoor air pollution by 50 to 75%, that reduction in pollution level was linked to a four-point reduction in systolic blood pressure – which the team estimates could translate into an 18% decrease in coronary heart disease and a 22% decrease in stroke among Asian women ages 50 to 59.