Air purifiers that draw air to trap particles are known as "mechanical filter" purifiers. They use at least one of the following filter types:
Sometimes called "panel filters," flat filters usually contain a fibrous material that can either be dry or coated with a substance like oil to aid in collecting and sticking particles. Flat filters can be composed of wood fill, animal hair, synthetic fibers or even aluminum slits. The low-efficiency furnace filter in many home heating systems is an example of a flat filter, but these typically remove a negligible percentage of smaller-sized particles that can end up in the lungs.
One of the best improvements to the standard flat filter was to increase the density of the material for the filter using smaller fibers and pleated material. Pleating increases the surface area of the filter to help keep airflow through the filter high. Compared to other dry filters, pleated filters have a much higher efficiency.
High Efficiency Particulate Air Filters (HEPA)
More popularly known as HEPA filters, these filters have been traditionally defined as an extended dry-type filter with an efficiency of at least 97.97% for all particles of 0.3-micron diameter. Buyers should be aware of less-efficient products billed as "HEPA-type" filters - their effectiveness at capturing particles and smoke can be as little as 55%.
While some air purifiers will accommodate different types of filters, others will only us a specifically designed filter that may not match your preference. If this is the case you'll either have to continue using whatever filters are available for your current air purifier, or you can choose to invest in a new one that accepts the filters that you like the best.
Switching to a new filter type or investing in a new purifier may be more costly in the short term, but you can't put a price on your health.