Clean rooms are defined as specially constructed, environmentally controlled enclosed spaces with respect to airborne particulates, temperature, humidity, air pressure, airflow patterns, air motion, vibration, noise, viable (living) organisms, and lighting. Particulate control includes:

1. Particulate and microbial contamination

2. Particulate concentration and dispersion

“Federal Standard 209E” defines a clean room as a room in which the concentration of airborne particles is controlled to specified limits.

“British Standard 5295” defines a clean room as a room with control of particulate contamination, constructed and used in such a way as to minimize the introduction, generation and retention of particles inside the room and in which the temperature, humidity, airflow patterns, air motion and pressure are controlled.