This global systematic literature review focused on indoor exposure to selected air pollutants associated with adverse health effects, and related household characteristics, seasonal influences and occupancy patterns, identifying relevant publications from six bibliographic databases. 141 studies from 29 countries were reviewed and information on indoor exposure levels and determinants, emission sources, and associated health effects was compiled for analysis. 

The most-studied pollutants were particulate matter (PM_2.5and PM₁₀); nitrogen dioxide (NO₂); common volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbons (PAHs) including naphthalene. PM_2.5 sources which were identified indoors include smoking, cooking, heating, use of incense, candles, and insecticides, while cleaning, housework, presence of pets and movement of people were the main sources of larger, coarse particles. Additionally, a significant contribution to PM_2.5 from outdoor air was identified in rooms with natural ventilation next to roads. Unvented gas heaters and cookers were found to be major sources of NO₂. Predictors of indoor NO₂ are outdoor NO₂ levels, ventilation and these changed with the season. VOCs are emitted from many indoor and outdoor sources, including smoking, solvent use, renovations, and household products. Formaldehyde levels are higher in newer houses and in the presence of new furniture, while PAH levels are higher in smoking households. 

High indoor particulate matter, NO₂ and VOC levels were typically associated with respiratory symptoms, particularly asthma symptoms in children. Home location near high-traffic-density roads, redecoration, and small house size contribute to high indoor air pollution. In most studies, air exchange rates are negatively associated with indoor air pollution. 

These findings can inform interventions aiming to improve IAQ in residential properties in a variety of settings.