Can the indoor air in our workplaces ever be safe from coronavirus? As dropping temperatures force us to close our office windows, this question becomes critical. We researched the two most promising options for portable air purification–HEPA filtration and the AirPHX system. Here’s what we found:

High-efficiency particulate air (HEPA) filters have a long track record for cleaning pollen, smoke, dust mites, and pet dander from the air. But they can also trap bacteria and viruses, especially in sneezed and coughed droplets. HEPA filters can remove 99.97% of airborne particles. And for a typically conditioned office, they can boost the air exchange rate from once in three hours to once every ten minutes.

This is huge improvement in indoor air quality, but it’s not foolproof. The finest HEPA filters will trap particles as small as 300 nanometers (nm), but an aerosolized coronavirus is less than 140 nm. And it’s these super-fine particles that linger in the air the longest. It’s also worth noting that filters don’t kill viruses, so you’ll want to use extra caution cleaning and changing filters, with PPE properly in place.

The AirPHX system doesn’t clean the air as efficiently as a HEPA filter, but for killing viruses, bacteria, and molds, it’s unmatched. AirPHX uses a non-thermal plasma to generate oxidizing molecules to destroy germs at a cellular level. Studies have shown it reduces viruses up to 95%, not only in the air but on contact surfaces. And unlike ozone-generating systems, the low levels of ozone an AirPHX system releases are quite safe.

Of course, the 5% of viruses remaining still constitute a risk. Neither of these solutions will take the place of mask wearing, hand washing, and social distancing. But we’re sold on the AirPHX system’s efficacy–literally. We’re buying one for our office.