Clean operating room cleanliness level standard description

grade	Maximum average concentration of settled (floating) bacteria		Maximum surface contamination density	Air cleanliness level
grade	Operating room area	Surrounding area	Maximum surface contamination density	Operating room area	Surrounding area
I	0.2 pieces/30min φ 90m (5 pieces/m3)	0.4 pieces/30min φ 90mL (10 pieces/m3)	5pcs/cm	Level 100	Level 1000
II	0.75 pieces/30min φ 90m (25 pieces/m3)	1.5 pieces/30min φ 90 mm (50 pieces/m3)	25pcs/cm	Level 1000	Level 10000
III	2 pieces/30min φ 90m (75 pieces/m3)	4 pieces/30min φ 90 mm (150 pieces/m3)	25pcs/cm	Level 10000	Level 100000
IV	5 pieces/30min, φ90 (175 pieces/m3)		25pcs/cm2	Level 300000

Other clean room grade standards for reference:

《Good Manufacturing Practice for Pharmaceuticals 》(revised in 1992)

Purification level	Number of live particles/cubic meter		Number of viable microorganisms/cubic meter
Purification level	≥0.5um	≥5um	Number of viable microorganisms/cubic meter
Level 1000	≤3,500	0	≤5
Level 10000	≤350,000	≤2,000	≤100
Level 100000	≤3,500,000	≤20,000	≤500