ISO class 최대허용 입자농도(개/m2) 0.1㎛ 0.2㎛ 0.3㎛ 0.5㎛ 1㎛ 5㎛ 1 10 2 2 100 24 10 4 3 1,000 237 102 35 8 4 10,000 2,370 1,020 352 83 5 100,000 23,700 10,200 3,520 832 29 6 1,000,000 237,000 102,000 35,200 8,320 293 7 352,000 83,200 2,930 8 3,520,000 832,000 29,300 9 35,200,000 8,320,000 293,000 Class 표시 미터법영국단위 Class 상한치 0.1 ㎛ 0.2 ㎛ 0.3 ㎛ 0.1 ㎛..