by Daniel Brouse
June 8, 2025
Far-UVC light, typically at a wavelength of 222 nanometers, has gained attention as a potentially safer alternative to traditional germicidal ultraviolet light (254 nm) for disinfecting public spaces, especially during and after the COVID-19 pandemic. While Far-UVC does not penetrate the skin or eyes as deeply as conventional UV light, its safety is still under active investigation, and there are important risks to consider—particularly with prolonged or high-dose exposure.
For the skin, Far-UVC is largely absorbed by the outermost dead cell layer, the stratum corneum, which limits its ability to reach living tissues. However, studies have shown that at high enough doses, Far-UVC can still cause erythema (skin redness) and DNA damage in superficial cells. These effects may be more pronounced in people with compromised skin barriers, such as those with cuts, thin or damaged skin, or in vulnerable populations like infants. Although some animal studies suggest a low risk of tumor formation, others raise concerns about whether repeated exposure might accelerate skin aging or increase cancer risk.
The eyes are particularly vulnerable to Far-UVC. While the light does not reach the retina, it is absorbed by the cornea and conjunctiva, where it can cause irritation, dryness, and in some cases photokeratitis—an inflammation similar to a sunburn on the eye. Because the eyes lack the protective outer layers that the skin has, they are considered a high-risk area for Far-UVC exposure, especially in settings with prolonged human presence.
Another area of concern is DNA damage. Far-UVC can still induce the formation of DNA lesions, such as cyclobutane pyrimidine dimers (CPDs), even if it doesn’t penetrate deeply. While the body has mechanisms to repair such damage, the long-term implications are still unclear, and there’s ongoing debate over whether chronic, low-level exposure may increase the risk of skin cancer or systemic effects through epigenetic changes.
Adding to the uncertainty is the lack of standardized safety regulations. While organizations like the American Conference of Governmental Industrial Hygienists (ACGIH) have issued provisional exposure limits, there is no universally accepted standard for safe daily exposure, especially in workplaces, schools, or hospitals. Until more long-term research is available, the use of Far-UVC in occupied spaces should be approached with caution.
In summary, while Far-UVC may offer a promising way to disinfect air and surfaces without the same level of harm as traditional UV light, it is not without risk. Safe implementation requires strict adherence to exposure guidelines, avoiding direct eye contact, and monitoring for signs of skin or eye irritation. Long-term studies are still needed to fully understand the effects of chronic exposure, and the current scientific consensus leans toward a cautious, carefully regulated approach.
Caution and Recommendation:
Far-UVC poses unknown long-term risks to human health, particularly to the eyes and skin with repeated or prolonged exposure. While current studies suggest it may be safer than conventional UV light, the lack of definitive safety data warrants a precautionary approach. The most effective and safest use of Far-UVC is to enclose it within HVAC systems, where it can disinfect circulating air without direct human exposure. This setup not only maximizes its pathogen-killing potential but also greatly reduces the likelihood of adverse health effects, making it a preferred strategy for schools, hospitals, offices, and other occupied indoor environments.