A layered IAQ + respiratory-mitigation strategy in buildings (when adopted locally) most typically combines (conceptual):

Choices

• (A) Filtration+OA+controls+GUV+portable+distancing+owner policy per ASHRAE/CDC/62.1/170 as applicable+AHJ
• (B) Eliminate all outdoor air
• (C) VRF in patient isolation rooms, always
• (D) Diesel exhaust through supply ducts, always