A new study finds that the heat setting you choose when doing laundry makes all the difference when it comes to killing dust mites. The researchers found that washing laundry in hot water--140 degrees Fahrenheit (60 ºC) or higher--kills all house dust mites, compared with just 6.5% of dust mites in laundry washed at 104 degrees Fahrenheit (40 ºC), or warm water. The study is being presented at the American Thoracic Society 2007 International Conference, on Sunday, May 20. Hotter water temperatures are also more effective in removing dog dander and pollen, says lead researcher Jung-Won Park, M.D., Ph.D., of Yonsei University in Seoul, Korea. There is an alternative to washing in hot water that's also effective, Dr. Park found: washing at a lower temperature (between 86-104° F, or 30-40 ºC), then rinsing the laundry twice with cold water for three minutes each. In the study, researchers compared allergen levels on cotton sheets after they were washed in various temperature settings. They found that since more pollen was left on the sheets when they were washed in cooler temperatures (86° F, or 30ºC), rinsing the sheets was especially important when using this temperature setting. "Optimal Conditions for Mechanical Laundry in the Removal of House Dust Mites, Dog and Pollen Allergens"(Session A93; Abstract # 2686) American Thoracic Society (ATS) 61 Broadway New York, NY 10006 United States