Air filters can reduce indoor fine particle concentrations by up to 60%, according to studies by Brauner et al. and Allen et al. A HEPA filter is designed to capture PM2.5 pollutants, such as tire and brake dust, from the air. However, it is not effective in removing VOCs or other gaseous pollutants like NOx, SO, or carbon monoxide.
To ensure optimal performance, HEPA filters should be replaced regularly. An air purifier can work in tandem with a HEPA filter to capture airborne allergens. The American Society of Heating, Refrigeration and Air Conditioning Engineers (ASHRAE) has a Minimum Efficiency Report Value (MERV) system for evaluating the efficiency of an air filter. This means that in addition to the purchase price of an air purifier, you also need to consider operating costs and filter replacement costs.
Over a period of 6 months, the effectiveness of air filters in capturing particulates and allergens was measured. While HEPA filters and other fibrous filters capture these contaminants, they do not destroy them, so regular maintenance is essential for proper functioning and protection. Air purifiers can neutralize some of the threat posed by air pollution and indoor activities. Some filters are reusable and washable, but require meticulous maintenance, so they are not usually found in the most effective air purifiers.
The use of HEPA filters traditionally used in hospitals has meant a significant inclusion in household air purifiers. One solution to improving indoor air quality (IAC) and worker productivity is to increase the amount of outdoor air pumped into the building, but even outdoor air can introduce pollutants such as mold, pollen or exhaust fumes into the environment. An air purifier can act as an adjunct to a filter and other strategies to help remove particulates. The EPA warns that while air purifiers can help reduce indoor air pollutants, cleaning the air alone is not enough to protect people from exposure to the coronavirus.
In air filters, the air was first filtered with a coarse pre-filter, followed by a ROTA filter, in which small dust particles were captured by high-speed rotation. There are some pollutants, such as carbon monoxide, that no filter is capable of removing from the air. OSHA describes indoor air quality as how “indoor air can affect a person's health, comfort, and ability to work”. Some air purifiers use ionizers to help attract particles such as static negative ions that bind to dust and allergens and cause them to settle in the air.