Indoor air quality
Indoor air quality describes the air inside homes, schools, offices, and other buildings, including pollutants, ventilation, moisture, and health-related comfort.
What indoor air quality means
Indoor air quality is the condition of air inside and around buildings as it relates to health, comfort, and performance. It includes pollutants people breathe, but also ventilation, humidity, temperature, odors, building materials, maintenance, cleaning products, and how people use the space.
Why indoor air matters
People spend much of their time indoors, so even moderate pollutant levels can matter if exposure lasts for many hours. Indoor air can contain pollutants generated inside the building, pollutants that enter from outdoors, or pollutants released from materials and activities. The mix changes by season, building type, and behavior.
Common pollutant sources
Indoor sources include fuel-burning appliances, tobacco smoke, candles, cooking, fireplaces, cleaning products, paints, building materials, pressed-wood products, pests, mold, dust, pets, and outdoor pollution that enters through leaks or ventilation. Some hazards, such as radon and carbon monoxide, are hard to notice without testing or alarms.
Moisture and biological pollutants
Moisture problems can support mold, dust mites, bacteria, and pests. Leaks, condensation, flooding, humidifiers, damp carpets, and poor drainage can all create conditions for biological contaminants. Fixing water problems and drying wet materials quickly is often more effective than trying to cover up odors or visible growth.
Ventilation
Ventilation brings outdoor air in and removes indoor air. It can dilute pollutants, reduce odors, and help control moisture, but outdoor air may need filtering when smoke, traffic pollution, pollen, or dust are high. Ventilation can be natural, mechanical, or a mix of both, and it works best when air actually reaches the breathing zone.
Filtration and air cleaners
Filtration captures particles from air that passes through a filter. Higher-efficiency HVAC filters and portable air cleaners can reduce particles when they are sized, installed, and maintained properly. Filtration does not remove every gas or fix a strong source, so it works best alongside source control and ventilation.
Source control
Source control means reducing or removing the pollutant source. Examples include repairing leaks, venting combustion appliances, choosing lower-emitting products, storing chemicals safely, not idling vehicles near buildings, using kitchen exhaust, banning indoor smoking, and maintaining heating and cooling systems. Source control is often the most direct IAQ improvement.
Why it matters
Indoor air quality matters because buildings can protect people or concentrate hazards. Good IAQ supports health, learning, work, sleep, and comfort. Poor IAQ can make existing health problems worse, create hidden risks during power outages or smoke events, and make everyday spaces less safe for sensitive groups.