What is a HEPA filter?

When looking into air purifiers, or anything with a filtration system, you may have seen a HEPA filter (or true HEPA) mentioned. But what is a HEPA filter? What are the benefits of using one?

What is a HEPA filter?

HEPA stands for High Efficiency Particulate Air. A HEPA filter is a specific type of air filter that has been specifically manufactured to reach a set standard. This standard details that a HEPA filter must remove at least 99.7% of particles from the air down to at least 0.3 microns in size.

We measure HEPA filter efficiency based on 0.3 micron particulates because these are the hardest to trap. Particles that are larger or smaller than 0.3 microns are even easier for the HEPA filter to trap, but using the worst case particle size represents the worst case efficiency of your filter.

To put that into perspective, the smallest things the human eye can see are around 70 microns in size. And those dust floaties that you might see in a beam of sunlight? These could be around 10 microns in size.

A HEPA filter is made up of thousands of very fine fibres that have been arranged into a mat to catch airborne particles. An air purifier, for example, will draw air in from the room, push it through the HEPA filter to be ‘cleaned’ and then release this air back out.

What are the benefits of a HEPA filter?

According to the Environmental Protection Agency, the concentration of certain airborne pollutants can be 2 to 5 times higher indoors than outdoors.

Large particles in the air can be breathed in and irritate the throat, which can cause coughing and allergy symptoms.

However it’s the smaller particles you really want to catch. Fine particles 10 microns or smaller can make their way deep into the lungs. This can then aggravate asthma and may even cause heart attacks in people with heart disease. Studies have also shown that long term exposure to high particle levels may even cause bronchitis, impaired lung function, and premature death.

What’s more, volatile organic compounds (VOCs) in the air can cause nose, throat, and eye irritation, as well as headache, nausea, and damage to the liver, kidneys, and nervous system. Some gases can even cause lung cancer and death.

In 2005 it was estimated that particle pollution caused 370,000 premature deaths in Europe.

Reasons to use a HEPA filter

New parents. Many new parents decide to use a HEPA filter in their child’s room so that their little ones aren’t breathing in unnecessary particles and pollutants.

Smokers. Thanks to a HEPA filter’s ability to remove smoke particles, many smokers decide to use one. You can double up on this effect with an activated carbon filter which will also remove the smell.

Pet owners. Pet dander in the air can cause allergies (and not to mention excess sweeping!) so many pet owners choose to use a HEPA filter to trap this excess, irritating dander.

Asthma sufferers. A well chosen HEPA filter can remove common household allergens like mould spores, dust mite faeces, and household dust particles. This in turn can help to manage the symptoms of asthma and prevent attacks.