If you notice a visible build-up of dust or particulate matter on a HEPA filter (it may look gray or dirty) or you notice reduced airflow through your portable air purifier, you may assume that this is an indication that the HEPA filter needs to be cleaned. However, experts suggest that HEPA filters should always be replaced rather than cleaned. A washable HEPA filter must be cleaned by rinsing it with cold water. You must be careful not to touch the filter material and to let it come into contact only with water.
Allow the filter to dry completely before reinstalling it. For example, some cartridge-type vacuum filters should only be washed on the outside of the filter, taking care not to wet the central part of the cartridge. These filters can be cleaned with cold or warm water. So, once again, check your user manual for best practices.
A permanent or washable HEPA filter can be cleaned and reused several times, as long as it is done correctly without damaging the filter. Most permanent HEPA filters can be cleaned gently with a vacuum, while a washable HEPA filter can be cleaned by rinsing it with cold water. Please note that there are no officially defined rules or terms that determine what type of product is considered permanent or washable. If you're not sure if the HEPA filter can be cleaned, look for the “washable” or “permanent” label on the air purifier box or on the website. Because the HEPA filter has a very narrow opening, contaminants that pass through it will be attached to the fiber during direct impact, diffusion, sieving or interception.
You can also find HEPA filters in many appliances, including medical air purifiers, vacuums, air conditioning systems, and cars. While a vacuum can absorb a lot of dirt and dust from the HEPA filter, it can also remove some of the fibers from the filter itself. Many of the best air purifier brands on the market come with a HEPA filter that is washable, allowing you to clean and reuse it. You can usually clean replaceable HEPA filters about once a month and change them every four to six months. However, there is no standard for washable HEPA filters, and there have been no public studies that test the operation of these filters after they have been washed. HEPA stands for high-efficiency air particles and is a type of mechanical filter that traps 99.97% of harmful airborne particles as small as 0.3 microns (0.00001 inches, 0.0003 mm).
Based on that data, vacuuming a HEPA might help a little bit but there's also a good chance that it won't do anything or even damage the filter. Learning to clean a HEPA filter can reduce pressure on your overall air purifier and help it last longer in your home. HEPA filters are made from a variety of materials such as plastic polypropylene (PP), polyethylene terephthalate (PET), nylon, wool, metals, sheets, plant fibers or fine glass fibers. Without a solid history of testing how to clean a HEPA filter with water or a vacuum it's unclear how that cleaning can degrade its performance.
