Scientists uncover side-effects of UVC-based air purifiers

Millions of UVC-based air purifiers run all day, everywhere from daycares and hospitals to retail stores and transport, eliminating viruses and bacteria from the air to keep us safe. But scientists have just discovered that when powered up, they create a surge in by-products, raising indoor air quality pollutants by up to 160 times.

The problem is that these units are used in occupied rooms, and occupants have no idea what they’re breathing in. Even scientists can’t predict the pollutants because it varies by room.

The report from the University of Helsinki, just published by the American Chemical Society, reports, “We find that the UVC (254 nm) caused dramatic increases in particle number concentrations, and nearly all (∼1000) monitored gas phase species also increased. These responses were unsurprising when considering the typical impacts of UVC on atmospheric chemistry.”

They focused on the so-called PM2.5 size of particles most associated with indoor air pollution because, at 2.5 nm, they are small enough to be inhaled deeply and absorbed by the lungs. The particulates sky-rocketed from just 16,000 per cubic inch to over 2.6 million.

These unintended pollutants eventually physically leave the room, but not before occupants have inhaled them. They found that the intermediary pollutants dissipate within 30-45 minutes, sucked out by the HVAC system.

In summary, it is inaccurate to think of UVC air purifiers as ‘quietly running 24/7 in the background, and cannot do any harm’. They do have unpredictable consequences for occupants while they are running.

What you can do if you have a UVC air purifier

  • Only use the purifier overnight in unoccupied rooms, and wait 30-45 minutes before re-entering.
  • If your unit only has a manual start and stop, it may be impractical to do this for every room, but if it can be scheduled on a timer, then use that to run it at night.
  • Evaluate an automated whole-room disinfection system such as EPIC iO AURA™, which is scheduled to run each night and disinfect both the air and all surfaces, leaving no by-products for occupants to inhale or touch in the morning.