When it comes to air purification, a high-efficiency particulate air (HEPA) filter is the standard recommended by the Environmental Protection Agency (EPA) and the American Lung Association. HEPA filters must trap 99.97% of contaminants that are 0.3 microns or larger in size, making them highly effective at removing a wide range of biological and non-biological particles from indoor air. To ensure you're getting true HEPA filtration, look for an air purifier that is certified according to EN 1822 standards. When selecting an air purifier, consider the square footage of the room you want to purify and choose a unit that is well sealed so that air does not escape before it reaches the filter.
If you're using the air purifier in a bedroom or baby's room, look for one that is relatively quiet even at higher speeds. Some manufacturers offer air purifiers that are certified to meet strict standards beyond HEPA, such as European Standard 1822 (EN 182). These filters can maintain 99.97% filtration in the worst case scenario and offer significant filtration beyond HEPA standards. You can find HEPA filters at most home improvement stores or online marketplaces.
To make sure you're getting the best performance from your air purifier, look for specific efficiency and particle size ratings as well as a highly sealed housing.