Which ISO Class requires less than 100,000 particles per cubic foot?

The correct response is based on the classification of cleanroom environments according to ISO standards, which specify the maximum allowable number of particles of different sizes in a given volume of air.

ISO Class 8 designates a cleanroom that allows for less than 100,000 particles of size 0.5 micrometers and larger per cubic foot of air. This specification indicates that environments classified as ISO Class 8 are appropriate for certain applications that do not require stringent control of contamination but still need to manage the presence of airborne particles.

In contrast, ISO Class 5 is much stricter, allowing for fewer than 3,500 particles of the same size. ISO Class 7 is also more stringent than Class 8, with a cap of 350 particles. ISO Class 9, on the other hand, is less strict than Class 8, permitting a greater number of particles. Thus, the delineation of particle count is crucial in understanding the levels of cleanliness required for different pharmaceutical or controlled environments.