More than half of asthma patients have attacks triggered by allergic reactions. While scientists search for the most effective methods to reduce asthma-triggering indoor allergens, experts say some simple steps can lower risk:

-Fully encase mattresses, boxsprings and pillows in special zippered covers to keep out dust mites and some other allergens.

-Wash sheets and pillowcases once a week in hot water, about 135 degrees. Energy-saving warm-water cycles can't kill dust mites.

-Decrease indoor humidity to less than 45 percent. Dust mites and roaches love high-humidity homes. Avoid humidifiers.

-Limit dust-collecting carpeting, drapes and clutter, particularly in children's bedrooms, the room where they typically spend more than nine hours a day. Keep pets out of bedrooms.
　　
　　(From healthy.net)