What is a HEPA filter?

A HEPA filter is  a specific type of high quality air filter that meets the HEPA filter standard, which is to remove at least 99.97% of particles from the air down to at least 0.3 microns in size. HEPA filters are a common component found in air purifiers which filter the air in order to clean it – there are other types of air purifier such as carbon filter, ionizers and even non-filter purifiers.

HEPA stands for High Efficiency Particulate Air. A HEPA air filter is made up of thousands of extremely fine fibres arranged into a matt to intercept both microscopic particles and larger ones. An air purifier will push air from the room through the filter to remove pollutant particles. By definition HEPA filters can trap close to 100% of the particles in the air that are 0.3 microns or smaller. (Bearing in mind that there are 10,000 microns in a centimetre. A particle 0.3 microns in diameter is really, really tiny.)

What HEPA air filters are good for

To understand how HEPA works, think of it as mesh of tangled fibers. The sheet is usually folded into pleats to increase the surface area and filter life. Air flows through the fibers and large enough particles get trapped when they hit the fibers. So it’s a size game which very clearly helps understand what HEPA can filter and what not.

HEPA works well and is effective at removing large enough particulate matter like pet dander, pollen, and dust mites. Other particulates can caught but continue to cause concern on the filter which we’ll explain in the next section.

Popular reasons for choosing it

• New parents – Thisfilter will remove pollutants from the air making it safer for young children (and adults) to breathe.
• Smokers– You need an air purifier with both a HEPA filter and a carbon filter inside. The first to remove smoke particles and the second to remove the fumes, gases and associated odour.
• Pet owners – A purifier with a life time HEPA filter will remove allergy causing pet dander from the air. Look for a purifier with both a HEPA and carbon filter to remove allergens and odour.
• Asthma Sufferers – A well chosen HEPA air purifier will removing common household allergens like mould spores, dust mite feces and household dust particles.. Allergy sufferers can enjoy refuge from the unpleasant symptoms.

When not to choose it?

Yes, although HEPA filters are fantastic there are occasions where a non-filter air purifier would be better.  For example if you want to kill airborne microbes and bacteria a model which works by incinerating particles, will destroy over  99.99% of micoorganisms. You see, as good a HEPA filters are, they cannot actually destroy anything. So things like mould spores, viruses and bacteria will continue to thrive unhindered unless they actually destroyed.