As sure as the sun rises, houses collect dust. It gathers on our knickknacks and dirties the carpets. More than just dirt, house dust is a mix of sloughed-off skin cells, hair, clothing fibers, bacteria, dust mites, bits of dead bugs, soil particles, pollen, and microscopic specks of plastic. It’s our detritus and, it turns out, has a lot to reveal about our lifestyle. For one thing, dust is far from inert. Those shed hairs and old skin cells can soak up a constellation of contaminants originating from consumer products that we bring into our homes. Other environmental contaminants can be tracked indoors on the soles of our shoes. So in addition to fluffy hair and garden dirt, dust can hold a witch’s brew of persistent organic pollutants, metals, endocrine disruptors, and more.