Dust is a common allergen . House dust contains mites (which are the primary cause of dust-related allergies ), microscopic particles of animal dander , pollen , mould , fibers from clothing and other fabrics and detergents.

Dust mites, the primary cause of dust allergy, are microscopic organisms found in homes. It is actually the excrement of these mites to which people are allergic, thus dust mites can cause allergic reactions even when dead.