If you have allergies or asthma, a tiny creature living in your home could be making big problems for you. Although you can’t see them, if you have allergies or asthma you may be feeling their effects only too well. They are dust mites, and they live in many homes throughout the world.

Dust mites may be the most common cause of year-round allergy and asthma. Household dust is not a single substance but rather a mixture of many materials. Dust may contain tiny fibers shed from different kinds of fabric, as well as tiny particles of feathers, dander from pet dogs or cats, bacteria, food, plant and insect parts, and mold and fungus spores. It also contains many microscopic mites and their waste products.

These waste products, not the mites themselves, are what cause allergic reactions. Dust mite waste contains a protein that is an allergen—a substance that provokes an allergic immune reaction—for many people. Throughout its life a single dust mite may produce as much as 200 times its body weight in waste.

Most dust mites die when exposed to low humidity levels or extreme temperatures. But they leave their waste behind, which continues to cause allergic reactions. In a warm, humid house, dust mites can easily survive year round. (Courtsey: