Indoor air quality (IAQ) refers to the quality of the air within and around building and structures, especially as it relates to the health and comfort of the occupants. IAQ can be affected by various gases, particulates, microbial contaminants or any mass or energy stressor that may induce adverse health conditions.

Source control, filtration and the use of ventilation to dilute contaminants are some of the methods for improving indoor air quality in most structures. Residential structures can also improve indoor air quality by routinely cleaning carpets and area rugs, which also function as air filters. The Environmental Protection Agency (EPA) has guidelines for frequency of cleaning based on traffic, number of household members, pets, children and smokers.

The IAQ may be determined via the collection of air samples and samples on a structure's surfaces, monitoring human exposure to pollutants and computer modelling of the air flow inside a particular structure.