[Clause 9.32.3.1.(2)(c)] To limit the probability of the inadequate replacement of indoor air with outdoor air, which could lead to excessive negative pressure in dwelling units, which could lead to the spillage of combustion products from fuel-burning appliances that are susceptible to spillage.
This is to limit the probability of the entry of carbon monoxide gas into living space, which could lead to the acute poisoning or asphyxiation of persons.
To direct Code users to Article 9.32.3.8. for requirements regarding protection against depressurization in heating-season mechanical ventilation systems in dwelling units with 5 or fewer bedrooms.