What is required for outdoor air treatment in compliance with ASHRAE Standard 62.1-2022?

• A. Outdoor air should be filtered only if occupants complain.
• B. Outdoor air must be suitable for use, with specific filtration requirements if particulate matter exceeds national standards.
• C. Outdoor air treatment is optional if building is small.
• D. Outdoor air must be cooled to 22 C before mixing.

Answer: (B)

Outdoor air quality is treated seriously in ASHRAE 62.1-2022. The standard requires that outdoor air brought into the building is suitable for use, and it establishes filtration requirements for that outdoor air when particulate matter in the outdoor environment exceeds national standards. In practice, this means you don’t just take outdoor air as-is; you evaluate its cleanliness and, if needed, provide filtration to bring particulates down to acceptable levels before mixing the outdoor air with return air for occupants. It isn’t about responding to complaints, it isn’t optional for small buildings, and there’s no requirement to cool outdoor air to a specific temperature before mixing.