A cleanroom is an environment, typically used in manufacturing or scientific research, with a low level of environmental pollutants such as dust, airborne microbes, aerosol particles, and chemical vapors. More accurately, a cleanroom has a controlled level of contamination that is specified by the number of particles per cubic meter at a specified particle size. Clean rooms play a crucial role in the manufacturing of products that are required to be free from microbial and particulate contamination and protected from moisture. Such products are manufactured and manipulated in cleanrooms, which are fitted with HEPA and, if required, ULPA filters as well as dehumidifier systems.
In a cleanroom environment, air particles are measured in microns (um). One micron equals one-millionth of a meter. Microns are the common unit of measure for sizes of biological cells and bacteria. Micron-sized particles are smaller than a living cell and can be seen only with the most powerful microscopes. To put this in perspective, one small dust particle seen in a ray of sun equates to approximately 60 microns. The human eye cannot consistently see objects less than 50 microns in size. Pollen is approximately 30-50 microns. Bacteria are approximately 2 to 10 microns in size. A typical indoor air sample may contain anywhere from 500,000 to 1 million particles per cubic foot of air.