A cleanroom is an environment, typically used in manufacturing, including of pharmaceutical products and scientific research as well as aerospace, semiconductor, engineering applications 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. In addition, the temperature and humidity is also controlled.