Can Air Purifiers and HEPA Filters Remove COVID Delta Variant?

Data shows face masks can protect you from COVID-19 and the delta variant, but what about air purifiers? Can air purifiers with HEPA filters remove COVID-19 and other viruses?

Can Air Purifiers With HEPA Filters Remove COVID-19 Delta Variant and Other Viruses?

To answer this question, we need to first answer if HEPA filters can capture particles as small as viruses, such as the COVID-19 delta variant. COVID-19 measures 0.06 – 0.14 microns in diameter.

Coronavirus virus particle size, can air purifiers capture coronavirus

HEPA filters – the workhorse of any purifier – must remove 99.97% of particles “greater than or equal to” 0.3 microns.

HEPA filter particle capture size 0.3µm; air purifiers coronavirus

But the definition only mentions particles 0.3 microns and above. What about smaller particles like the coronavirus and other viruses?  Can HEPA filters capture these?

This exact question has led to years of confusion and false advertising claims about HEPA filters. This had led to confusion on HEPA filter’s effectiveness in capturing virus-sized particles.

coronavirus size too small for masks

Why HEPA Filters Are Great at Removing COVID-19 & Other Viruses

The fact that HEPA filters are so good at removing tiny virus particles like COVID-19 is surprising. It’s surprising because our intuition about filters is wrong. Like most people, I had the intuition that HEPA filters work like a net.

HEPA filters - do they capture particles like a net?

If a particle is smaller than the holes in the net, it gets through. Makes sense! However, it turns out that particles as small as the coronavirus, and other nano-particles get captured using a scientific phenomenon called diffusion.

Learn more about the science behind diffusion and how it captures nano-particles »

Diffusion is surprisingly effective at capturing tiny virus-sized particles. According to NASA, HEPA filters capture “virtually 100% of particulates.”

NASA nanoparticles HEPA capture

Researchers at the University of Minnesota tested this question with weaker fiberglass furnace filters and higher-grade HEPA filters. In their test, they shot particles of silver from 3 to 20 nanometers at the filters (that’s roughly 5 to 30 times smaller than coronavirus particles).

HEPA Filters Capture Nanoparticles; air purifiers capture coronavirus

The results showed that filters captured 99.99% of particles smaller than 5 nanometers. Bingo! HEPA filters are incredibly effective at capturing nanoparticles–even smaller than the coronavirus.

Read More: Can UV light Kill the Coronavirus?

Do I Need a Medical Grade Air Purifier to Remove COVID-19 Delta Variant?

It may seem logical that in order to filter out viruses like COVID, a medical grade air purifier is needed. Turns out, medical grade air purifiers are more often than not a marketing gimmick. Normal HEPA filter air purifiers can filter viruses extremely well.

Caveat: HEPA air purifiers are not a silver bullet. They can filter out viruses from the air in homes, offices, and schools, but other steps such as good hygiene and disinfectants should still be used in conjunction with HEPA air purifiers.

Bottom Line: Can Air Purifiers Capture The Coronavirus?

Air purifiers that contain HEPA filters or even lower grade filters can capture virtually all sizes of solid particles, including particles 0.1 microns in diameter – or the same size as the coronavirus.

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Explore more: What types of filters do I need to protect myself from all types of pollutants?


How I Protect Myself Against COVID-19 and the Delta Variant

Smart Air is a  certified B Corp committed to combating the myths big companies use to inflate the price of clean air.

Smart Air provides empirically backed, no-nonsense purifiers and masks, that remove the same particles as the big companies for a fraction of the cost. Only corporations benefit when clean air is a luxury.

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Smart Air is a social enterprise that creates simple, no-nonsense air purifiers and provides free education to protect people’s health from the effects of air pollution. We are proud to be the only certified B-Corp dedicated to fighting air pollution.