Building code  Title 27 / Subchapter 12

Prohibited use of recirculated air.- Air drawn from
any of the following spaces may not be recirculated;*
mortuary rooms; bathrooms or toilet rooms; or any space
where an objectionable quantity of flammable vapors,
dust, odors, or noxious gases is present. Air drawn from
rooms that must be isolated to prevent the spread of
infection shall not be recirculated, except that air drawn
from hospital operating rooms may be recirculated, if in
compliance with the following requirements: