Contamination typically refers to the number of particles in an environment.
The particles are often measured in microns.
- The unaided eye can see particles as small as 50 microns on a good background
- The thickness of a human hair is 100 microns
- Time to fall 1 metre in still air for a 10 micron particle is 33 seconds, for a 1 micron particle is 48 minutes
Particles can:
- Change the appearance of materials
- Change the properties of materials