What is the primary measure of air cleanliness in ISO Class systems?

The primary measure of air cleanliness in ISO Class systems revolves around the concentration of particulate matter. ISO Class systems are defined by the allowable number of particles of specific sizes present in the air. Each class specifies limits for particulates that can affect processes sensitive to contamination, particularly in environments like cleanrooms.

Particulate matter concentration is crucial because even small contaminants can compromise the integrity of pharmaceutical products, medical devices, and other applications where sterility is paramount. By establishing a standard measurement for particulate matter, ISO Class systems can ensure that the air quality meets rigorous requirements to maintain product safety and efficacy.

In contrast, while temperature, humidity, and chemical contaminants play roles in overall environmental conditions, they are not the primary indicators used to classify air cleanliness in ISO Class systems. Temperature and humidity can impact product stability and the comfort of staff within cleanrooms, but they do not directly reflect particulate levels. Chemical contaminants, although significant in monitoring the overall cleanliness of an environment, do not define the ISO Class standards related to airborne particulates. Thus, the focus on particulate matter concentration is what solidifies it as the correct measure for air cleanliness classification in ISO standards.