Credit :José-Luis Olivares, MIT
Key points:
- Devices that use UV light at a safe 222 nanometer wavelength to kill pathogens also produce harmful air pollution compounds when used indoors.
- UV light interacts with oxygen to form ozone and OH radicals that are especially harmful in areas with low ventilation rates.
- To utilize these devices properly, it is critical to identify the potential negative health impacts and ensure proper ventilation.
New efforts to reduce disease transmission have focused on UV light sources. These devices, called KrCl excimers, use UV light at a safe 222 nanometer wavelength to kill pathogens, including SARS-CoV-2. However, a recent study, published in Environmental Science and Technology, finds that these UV lights can produce potentially harmful compounds when used indoors.
Devices that clean indoor air via UV light bring air pollution and oxidation indoors. The UV light interacts with oxygen in the air to form ozone, which on its own poses a health risk. UV radiation can also interact with ozone, producing OH radicals that are powerful, harmful oxidizers.
Since people spend a substantial amount of time indoors, the formation of these compounds becomes problematic. Additionally, low ventilation rates cause the accumulation of these compounds at high and potentially hazardous levels.
To assess pollution-forming processes indoors, researchers exposed clean air to the UV lights inside a controlled Teflon container and then added one organic compound at a time to observe their impact on the produced compounds. Although this experiment did not precisely replicate indoor environments, it clearly demonstrated the formation of secondary products under UV radiation.
“Our big finding was that these lights are not a replacement for ventilation, but rather a complement to it,” said Jesse Kroll, professor at MIT.
Due to their high cost, these devices have been mainly used in hospital, restaurant, and commercial settings. As they gain popularity and are deployed in more settings, it is critical to fully consider the potential benefits and risks associated with their operation.
“This work lays the foundation for a proper qualification of potential negative health impacts of these devices,” explained Dustin Poppendjeck, a research scientist at the National Institute for Standards and Technology. “It is important this process is completed prior to relying on the technology to help prevent the next pandemic.”