Indoor Air Quality (IAQ) refers to the air quality within and around buildings and structures, especially as it relates to the health and comfort of building occupants. Increasing the amount of outdoor air coming into the building helps to control pollutant levels, odors, temperature, humidity, and other factors that can impact the health and comfort of building occupants.
The rate at which outdoor air replaces indoor air is described as the air exchange rate. ASHRAE (formerly called the American Society of Heating, Refrigerating and Air-Conditioning Engineers) recommends (in its Standard 62.2-2016, "Ventilation and Acceptable Indoor Air Quality in Residential Buildings") that homes receive 0.35 air changes per hour but not less than 15 cubic feet of air per minute (cfm) per person. as the minimum ventilation rates in residential buildings in order to provide IAQ that is acceptable to human occupants and that minimizes adverse health effects. ASHRAE also suggests intermittent exhaust capacities for kitchens and bathroom exhaust to help control pollutant levels and moisture in those rooms. ASHRAE also notes that "dwellings with tight enclosures may require supplemental ventilation supply for fuel-burning appliances, including fireplaces and mechanically exhausted appliances.