Table II

EU Air Classifications

ISO Class DesignationEU GradeMaximum Permitted Number of Particles per Cubic Meter Equal to or Greater Than the Tabulated Size
Recommended Limits for Microbial Contamination during Operationa—Air Sample (cfu/m3)
At Rest
In Operation
≥0.5 μm particles/m3≥5.0 μm particles/m3≥0.5 μm particles/m3≥5.0 μm particles/m3
5 at rest 7 in operationB352029352,000290010
7 at rest 8 in operationC352,00029003,520,00029,000100
8 at restD3,520,00029,000Not definedNot defined200
  • a These are average values.

  • b ISO 4.8 is dictated by the limit for particles ≥5.0 μm.