Dust is very small pieces of matter in the air or on surfaces. Dust particles are made of different things including dirt, material from volcanic eruptions, and pollution. Dust can also contain small amounts of plant pollen, hair from people or animals, skin cells, and many other things. Dust in outer space makes nebulas.
- Kathleen Hess-Kosa, (2002), Indoor Air Quality: sampling methodologies, page 216. CRC Press.