Common dust is made up of many different components, including ash, smoke, dirt, sand, salt, pollen, bacteria, bits of textiles and paper, human and animal hair and skin particles, and even meteorite particles.
A surprising amount of dust rains down from space in the form of “micrometeorites,” on the scale of 14-50 tons per day. This is roughly 1-3 garbage trucks worth of space dust daily.
The massive Sahara Desert is the largest source of mineral dust in the world, with airborne Saharan dust regularly reaching Europe, the Amazon, Asia, the Caribbean and the Americas.
The old myth about household dust being mostly dead skin is not true. Most studies on indoor dust composition show that the largest part of household dust came from sources outside the house.
You are, however, still a major source of dust. Your endlessly-regenerating skin layer sheds nearly a million dead cells daily.
Dust makes up that gross layer on top of your fan blades…and some of the largest structures in the universe. Nebulae, those clouds of gas and dust which often came from exploding stars and can eventually congeal into new ones, can be millions of light years in diameter.
Unfortunately, dust can be bad news for those in certain occupations. Pneumococcus, the umbrella term for extensive dust-caused scarring in the lungs, affects people working in mining (“black lung”), drilling, textiles, agriculture, shipworking, sandblasting, and other dust-intensive jobs.