We like to boast that our vacuums are equipped with HEPA filters. But what are those and why are they important to your home?
What Are They?
HEPA filters are just filters that are exceptionally good at removing particles from the air. The acronym stands for “high-efficiency particulate arrestance” or “high-efficiency particulate arresting.” There is a range of different efficiencies, but to qualify as a HEPA filter and meet the standards of the US Department of Energy, the filter must remove from the air that passes through it at least 99.97% of particles as small as 0.3 microns.
How They Work
HEPA filters are not sieve-like filters that allow any particle smaller than its largest opening through. HEPA filters are mats made of randomly arranged fibers (usually glass) and they trap particles in three ways:
Interception: A particle comes in contact with a fiber and sticks to it.
Impaction: A larger particle cannot avoid the fibers while following the airstream through the filter. As a result, it smashes into a fiber directly.
Diffusion: This one is more complicated and has to do with things like Brownian motion and statistics, but essentially at lower airspeeds much smaller particles bump larger particles around and increase the chances that as they wander through the filter they will stick to a fiber.
What They Remove
HEPA filters remove particles such as pollen, bacteria, dust mite feces, pet dander, hair, and mold spores. They do not remove gasses or odor molecules as they are too small.
Why HEPA Matters
By removing aggravating substances from the air, vacuums with these filters are particularly helpful for allergy or asthma sufferers. However, they are beneficial to everyone that wants to breathe cleaner air. Additionally, some studies have shown having air filtered with a HEPA grade filter can improve cardiovascular health and the functioning of small blood vessels.