Indoor Air Quality
Indoor air contains pollutants that can affect human health. Some of these pollutants come from outdoors, and others come from indoor sources and activities, such as cooking, cleaning, secondhand smoke, building materials, consumer products, and home furnishings. These indoor air pollutants can be particles or gases, including volatile organic compounds (VOCs). Common contaminants that can be found indoors include particulate matter (including PM2.5 [fine] and PM10 [coarse]), formaldehyde, mold, and pollen. Indoor air quality will vary from home to home and over the course of a day within a home. Since most people spend about 90% of their time indoors, mostly in their homes, much of their exposures to airborne pollutants will happen in the home.
The most effective ways to improve your indoor air are to reduce or remove the sources of pollutants and to ventilate with clean outdoor air. In addition, research shows that filtration can be an effective supplement to source control and ventilation. Using a portable air cleaner and/or upgrading the air filter in your furnace or central heating, ventilation, and air-conditioning (HVAC) system can help to improve indoor air quality. Portable air cleaners, also known as air purifiers or air sanitizers, are designed to filter the air in a single room or area. Central furnace or HVAC filters are designed to filter air throughout a home. Portable air cleaners and HVAC filters can reduce indoor air pollution; however, they cannot remove all pollutants from the air.
Source: https://www.epa.gov/indoor-air-quality-iaq/guide-air-cleaners-home