Dust mites: the bedroom ecosystem you cannot see

House dust mites, primarily Dermatophagoides pteronyssinus and D. farinae, are microscopic arachnids that live in mattresses, pillows, upholstery, and carpet. They feed on shed human skin (a typical adult sheds about 1.5 g/day, ample food for several million mites in a queen-size mattress). The mites themselves are harmless; the problem is the proteases they secrete and the fecal pellets they leave behind, both potent allergens.

The two key dust-mite allergens, Der p 1 and Der f 1, are present in airborne dust whenever a mattress is shaken, sheets are pulled, or carpeted floors are walked on. They are bigger than fine PM (most fall in the 10–40 µm range, PM₁₀ territory) and settle within minutes, but during disturbance they aerosolize readily.

Arlian's ecology data are unambiguous: dust mites cannot maintain water balance below ~50% RH and reproductive populations collapse over a few weeks. The single most-effective intervention is lowering bedroom humidity to 40-45% RH. Allergen-impermeable mattress and pillow encasings keep existing allergen out of the breathing zone; weekly hot-water (≥55 °C) laundering of bedding kills both mites and denatures the allergen proteins.

Dashboard inference: when bedroom RH sits above 55% overnight for weeks and PM₁₀ spikes coincide with bed-time and wake-time, the most likely (though not certain) explanation is a dust-mite-laden bedroom. EPA ranks dust-mite allergen exposure as one of the top three indoor asthma triggers in North America.

This is environmental information, not medical advice. The dashboard's readings help you make decisions about the air in your space. They do not diagnose conditions, interpret symptoms, or replace conversations with your physician. If symptoms persist, worsen, or coincide with a known exposure, talk to a healthcare professional. See the AI's medical-advice scope.