Two new studies led by University of California, Berkeley, researchers spotlight the human health effects of exposure to smoke from open fires and dirty cookstoves, the primary source of cooking and heating for 43 percent, or some 3 billion members, of the world's population. Women and young children in poverty are particularly vulnerable. In the first study, the researchers found a dramatic one-third reduction in severe pneumonia（肺炎） diagnoses among children in homes with smoke-reducing chimneys on their cookstoves. The second study uncovered a surprising link between prenatal maternal exposure to woodsmoke and poorer performance in markers for IQ among school-aged children.

The findings on pneumonia, the chief cause of death for children five and under, will be published in the journal The Lancet on Nov. 10, two days before World Pneumonia Day. While previous research has linked exposure to household cooking smoke to respiratory（呼吸的） infections, the latest results come from the first-ever randomized controlled trial -- the gold standard of scientific experiments -- on air pollution.

"This study is critically important because it provides compelling（引人注目的） evidence that reducing household woodsmoke exposure is a public health intervention that is likely on a par with vaccinations and nutrition supplements for reducing severe pneumonia, and is worth investing in," said Kirk Smith, professor of global environmental health at UC Berkeley's School of Public Health and principal investigator of the RESPIRE (Randomized Exposure Study of Pollution Indoors and Respiratory Effects) study. "There is a huge burden of disease and death due to child pneumonia, and there aren't a lot of good interventions out there," added Dr. Arthur Reingold, a UC Berkeley professor of epidemiology（传染病学） and an internationally recognized expert on infectious diseases, who was not part of the RESPIRE trial. "Randomized controlled trials are frequently demanded by funding agencies and decision makers before they are willing to make substantial investments in new technologies or strategies, and this study provides the needed evidence of an intervention that works."

In the RESPIRE study -- which includes partners from Guatemala's Universidad Del Valle, the U.S. Centers for Disease Control and Prevention, University of Liverpool, Norway's University of Bergen and the World Health Organization -- researchers worked with rural communities in the Western Highlands of Guatemala. Households with a pregnant woman or young infant were randomly assigned to either receive a woodstove with a chimney or to continue cooking with traditional open woodfires.