Anj E is on the right track, but has provided you with some misconceptions, if I understood her reply correctly.
Household dust is not necessarily full of (live) dust mites, however, 80% to 90% of the ALLERGENIC composition of household dust is from dust mite feces, dust mite molts (they go through 6 stages of life and molt each time), exoskeletons, dead dust mites pieces, egg sacs, and other dust mite excretions.
Skin contact for those who are allergic to dust mite allergens (DMA's) routinely results in a bad case of eczema. Inhalation of DMA's routinely results in a multitude of varying symptoms and adverse ill-health effects.
While dust mites are light-weight enou