Each place's atmospheric dust is unique

Dust mites eat animal dander, human skin, and some fungi. We shed dead skin cells constantly, and wherever we live, they mix into the household dust. The same goes for our pets: their dander and hairs enter the mix, as do tiny pieces of thread and cotton fibers from our clothes. These components make every household’s dust a unique blend of bits from its particular inhabitants. Household dust also contains substances that blow in from the wider world. Depending on the local geology, finely ground quartz, coal, or volcanic ash might enter the air as atmospheric dust, along with pollen and fungal spores. Industrial activities also contribute cement powder, particles from car tires, and other chemicals to the airborne mix.The combination of these elements can be as unique as a fingerprint.