Which ISO Class allows for less than 100 particles per cubic foot?

ISO Class 5 is defined by a maximum particle count of fewer than 3,520 particles of size 0.5 micrometers or larger per cubic meter, which translates to less than 100 particles per cubic foot. This classification is suitable for environments where high levels of cleanliness are required, such as in sterile compounding areas in pharmacies. The strict limits on particle counts in ISO Class 5 ensure that any critical processes that involve sterile products are conducted in a controlled and safe environment, minimizing the risk of contamination.

In contrast, the other ISO classes have higher allowable particle counts, thereby making them less clean than Class 5. For instance, ISO Class 7 permits up to 352,000 particles per cubic meter, which would exceed the particle limit for ISO Class 5. This illustrates the significance of ISO Class 5 in terms of maintaining a sterile environment, crucial for certain pharmaceutical operations.