A clean room refers to a space available for human activity in which the air cleanliness reaches a specified air cleanliness class, and which has the ability to control pollution.

[Reference] A room in which the concentration of airborne suspended particles is controlled. Its construction and use should reduce the introduction, generation, and retention of particles indoors, and other relevant indoor parameters such as temperature, humidity, and pressure are controlled as required.

[Reference] Clean rooms have the following characteristics in terms of function, design, structure, and construction (Table 1.4).

Table 1.4　Characteristics of Clean Rooms

Functionally In design Structurally In construction
Prevent particle generation Three-stage filtration No particle generation Clean and dry
Prevent particle entry Terminal filtration No particle accumulation Tight and smooth
Effectively remove particles Airflow direction conducive to particle settling and removal Does not hinder particle removal Construction according to procedures

[Reference] A clean room must control not only the indoor temperature and relative humidity, but also dust, bacteria, pressure, harmful gas concentration, and airflow distribution. Most importantly, it must control the indoor concentration of particles (bacteria or dust).