What is the significance of outdoor air quality in ASHRAE Standard 62.1-2022?

• A. Outdoor air quality must comply with regional ambient air quality standards, including NAAQS attainment status.
• B. Outdoor air quality is not considered in the standard.
• C. Only indoor contaminants matter for IAQ.
• D. Outdoor air quality dictates the HVAC system energy use.

Answer: (B)

Outdoor air quality is not part of the design criteria that ASHRAE 62.1-2022 uses to determine whether a space meets IAQ targets. The standard focuses on how much outdoor air to supply, how it’s treated (filtration, air cleaning), and how those measures achieve acceptable indoor air quality, regardless of the current status of ambient outdoor air. Regulatory ambient air standards (like NAAQS attainment) are outside the scope of 62.1; the standard does not require outdoor air to meet those standards as a condition for compliance. In practice, outdoor air quality can influence system design (e.g., need for better filtration or intake location), but the IAQ requirements themselves are defined independently of external ambient air quality.