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How Does a HEPA Filter Work?

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Through improving the quality of air in a room, air purifiers can help you manage asthma and pet allergies, and they can help you sleep better if you suffer from hayfever.

And all of these benefits are largely thanks to the air purifier’s HEPA filter. HEPA filters are very effective. Up to 99.97% effective, in fact! And they work fast, too. With our air purifiers, you can start breathing much cleaner air in just over 12 minutes.

But what is a HEPA filter, and how does it work?

What is a HEPA Filter?

A HEPA filter is a “high-efficiency particulate air filter”. A HEPA filter is simply a number of thin layers of fibre laid on top of each other. HEPA filters can be made from a range of materials. Our range of air purifiers, for example, use a combination of fabric pre-filters and a recyclable mesh inner filter.

How Does a HEPA Filter Work?

Basically, a HEPA filter allows air to pass through while trapping any potentially harmful particles and pollutants. But to put it like this, you might think that a HEPA filter works like a net, or a sieve. But this isn’t quite the case. A net or a sieve will catch anything that’s bigger than its holes. But HEPA filters are capable of catching particles so small they could fit through even the tiniest of holes.

Simply put, the fibres that make up the filter are layered randomly, creating an almost impenetrable maze. Air can pass through this network of fibres without issue. But any particles and pollutants contained within the air will get caught.

Different sized particles will get caught in different ways. The smallest particles, for example, tend to travel in zig-zag patterns through the air. So as they pass through the tangled maze of fibres in the HEPA filter, they’ll almost always end up hitting a fibre – a process called diffusion.

So in short, polluted air will go into the HEPA filter, but much cleaner air will leave it.

How Effective are HEPA Air Filters?

HEPA filters are very effective. The clue’s in the name – they’re “high-efficiency particulate air filters”! Not all air filters are HEPA filters. In order to legally qualify as a HEPA filter, the filter must remove 99.95% of particles in the air.

Our air purifiers use advanced HEPASilent technology that’s capable of capturing at least 99.97% of all airborne particles, down to 0.1 micron in size. This includes:

  • Dust
  • Pollen
  • Mould
  • Pet dander
  • Smoke
  • Bad odours

Our air filters can even trap and kill certain viruses and bacteria. They can completely filter the air in a room of up to 36m² every 12.5 minutes. See our range of air purifiers using HEPASilent technology.

But in order for a HEPA filter to remain effective, you’ll have to change the filter once every six months or so. We stock replacement particle and carbon filters, and we offer fabric pre-filters in a range of colours. So when it’s time for a change, you could also try mixing things up with a new colour.

Do I Need a HEPA Filter?

Here are some situations in which our air purifiers can make a significant difference:

  • You or your child has allergies – either to pets, pollen, dust, or something else.
  • There’s a busy road near your house, and you’re worried about air pollution.
  • You want to remove lingering smells from your home – whether it’s from pets, smoke, or cooking.

The recent pandemic also highlighted how good air circulation can help prevent the spread of airborne viruses. To this end, a HEPA filter can prove much more effective than an open window.

For more information, read our complete guide: Do air purifiers work and are they worth it?

You can also browse our complete range of air purifiers and replacement filters.

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