DEFINATION: A clean room is an environment,typically used in manufacturing or scientific research, that has a low level of environmental pollutants such as dust, airborne microbes, aerosol, particles and chemical vapours. More accurately, a clean room has a controlled level of contamination that is specified by the number of particles per cubic meter at a specified particle size. For example to give a perspective, the ambient air outside in a typical urban environment might contains as many as 35,000,000 particles per cubic meter,0.5 micron and large in diameter,corresponding to an ISO class  clean room over view: clean room can be very large.entire manufacturing  facilities can be contained within a clean room with factory floors covering thousands of square meters.they are used  extensively in semiconductor manufacturing, biotechnology and other fields that are very sensitive to environment.