This guideline establishes best practices for maintaining indoor air quality and HVAC system performance during wildfire smoke events. It applies to commercial, institutional, multi-unit residential, healthcare, educational, and other specialized buildings, covering new construction, retrofits, and operational measures. The focus is on reducing occupant exposure to wildfire smoke, particularly fine particulate matter (PM₂.₅), which can penetrate deep into the lungs and contribute to respiratory, cardiovascular, and cognitive health effects. Without mitigation, indoor air quality can quickly deteriorate during severe smoke events.