The clean area should maintain a positive pressure of not less than 10Pa for the unclean area connected with it, and the clean area should maintain a positive pressure of not less than 15Pa for the outdoor or the area directly connected with the outdoor, and all the pressure differences should not be greater than 30Pa.

There should be a buffer room with an area of not less than 3m2 between the clean area and the unclean area, and the cleanliness level should be the same as the side with high cleanliness, and should not be higher than 1000 level.

The number, size and air cleanliness level of clean operating rooms in the clean surgery department should be determined according to the nature, scale, level and financial resources of the hospital. For general hospitals, when L-class clean operating rooms need to be built, the number of such clean operating rooms should not exceed 15% of the total number of clean operating rooms, at least 1; One negative pressure clean operating room can be set up if necessary. For specialized hospitals, the number of special clean operating rooms should be determined according to actual needs.