What does the term 'air classification' refer to in ASHRAE Standard 62.1-2022?

• A. The categorization of air quality into classes 1 to 4 based on contamination levels and irritation intensity.
• B. A method for labeling air flow directions.
• C. A ranking system for HVAC contractor performance.
• D. A system for classifying outdoor weather conditions.

Answer: (A)

Air classification in ASHRAE 62.1-2022 refers to the system of grouping air quality into categories (class 1 through class 4) based on contaminant levels and the potential for irritation. This classification helps designers decide how much outdoor air to bring in, what filtration and source-control measures to use, and how strict the IAQ requirements should be to achieve acceptable indoor air quality. The other ideas—labeling airflow directions, ranking contractor performance, or classifying outdoor weather—are outside the scope of how this standard handles indoor air quality classifications.