To limit the probability that occupants will disable outdoor air supply fans, which could lead to excessive negative pressure, which could lead to the spillage of carbon monoxide gas from fuel-burning appliances that are susceptible to spillage, which could lead to the acute poisoning or asphyxiation of persons.
To exempt mechanical air exhausting devices that are principal ventilation fans operating at a rate not greater than the maximum permitted in Table 9.32.3.3. from the provisions in Article 9.32.3.8. for outdoor make-up air fans, on the basis that Articles 9.32.3.4. and 9.32.3.5. address outdoor make-up air for the principal ventilation fan.