According to the JIS (Japanese Industrial Standards) definition, a Cleanroom is a limited, contamination-controlled room in which fine airborne particles, airborne microbes and molecular contaminants are maintained below a set level of cleanliness. In addition, materials, pharmaceuticals and water provided to the room are also maintained at the required level of cleanliness, and environmental conditions within the room such as temperature, humidity and air pressure are also controlled as necessary. In Cleanrooms, it is important to minimize the amount of airborne particles and other contaminants, and level of cleanliness (class) is the value indicating how clean the room is.
It is not limited to dust. Hospitals, for example, require sterile environments. Food plants are similar and also need to control temperature and humidity.
In order to create these environments, cleanrooms are capable of reducing airborne particles and controlling temperature, humidity, air pressure, trace gas components, static electricity, micro-vibrations, electromagnetic waves and more.
On the other hand, handling pathogenic bacteria and recombinants DNA requires a room that possesses negative pressure in comparison to the surrounding environment and that is so gas-tight that microbe will not be leaked externally. These are called biosafety rooms (BSL-3). And CPFs are used when conducting cell processing of iPS cells, etc.