A clean room is defined as a room that limits the concentration and the size of air born particles.  In addition, the temperature and the humidity of the environment are controlled according to specific customer requirements. It is common in the HVAC industry to reference the Federal Standard 209D to identify such room classifications and is shown in the table below.  However, the latest Federal Standard 209E exceeds these minimum requirements and offer further room classifications.

 

class	Particle size (mm)
	0.1	0.2	0.3	0.5	5.0
1	35	7.5	3	1	NA
10	350	75	30	10	NA
100	NA	750	300	100	NA
1 000	NA	NA	NA	1000	7
10 000	NA	NA	NA	10000	70
100 000	NA	NA	NA	100000	700

 

Number of particles per cubic foot whose size is greater or equal to particle size.

The clean room protocol that must be adhered to in a clean room requires people entering in a clean room have to wear special coats, overshoes, gloves, face mask, and to clean any object they need to bring inside.