Why is Far-UVC Safe for Human Exposure?

Far-UVC light (typically at 222 nm) is an effective disinfection technology that can inactivate microorganisms without posing a hazard to human health.

In this blog post, we will go over the safety of Far-UVC, which has been studied for over a decade. Below, we summarize some of the key findings from peer-reviewed scientific literature that explain why Far-UVC is considered safe for human exposure, as well as a list of all published safety studies.

Far-UVC is Absorbed by Protein in Dead Skin Cells

Far-UVC light is strongly absorbed by proteins in the outermost layers of the skin and eyes. Its short wavelength (222 nm) prevents it from penetrating beyond the stratum corneum (the outer dead-cell layer of skin) or the tear film and outermost corneal layer of the eye. This absorption effectively stops Far-UVC from reaching living cells where damage could occur.

Extreme Exposure Study Shows High Safety Margins

A real-world case study found that human skin can tolerate extremely high doses of filtered Far-UVC light. A volunteer exposed his forearms to doses nearly 800 times the ICNIRP TLV (23 mJ/cm²), yet experienced no burns or skin damage. Only at very high doses (above 6000 mJ/cm) did a faint yellowing occur, which faded within hours. Tests confirmed that the effect was superficial and did not reach living skin layers (Eadie et al.,2021).

Long-Term Exposure Evidence on Far-UVC Safety

Multiple long-term studies in mice have confirmed that filtered 222 nm Far-UVC light does not cause tissue damage, even with prolonged exposure.

• In a 66-week study, UV-sensitive hairless mice were exposed to Far-UVC five days a week for eight hours a day at doses far above the ICNIRP TLV (23 mJ/cm²). Researchers found no increase in skin tumors, unusual growths, or tissue changes, and health outcomes were similar to unexposed control groups (Welch et al., 2022).
• To test Far-UVC safety, one study used both normal and UV-sensitive hairless mice, known for their susceptibility to develop UV-induced skin cancer. Despite their vulnerability, no tumors or inflammation developed after repeated 222 nm exposure (Yamano et al., 2020).
• Another study used both normal and UV-sensitive hairless mice, known for their susceptibility to develop UV-induced skin cancer. Despite their vulnerability, no tumors or inflammation developed after repeated 222 nm exposure (Yamano et al., 2020).

A growing body of consistent evidence points to the same conclusion: filtered 222 nm Far-UVC light can provide effective disinfection without harming the skin, even in the long term.

Eye Safety: Evidence from Laboratory and Real-World Studies

One of the most common concerns about UV light is its potential to harm the eyes. However, studies indicate that properly filtered Far-UVC light (222 nm), like UV Medico's products,  poses minimal risk, even with regular exposure.

• A study using rats showed that Far-UVC only reaches the very outermost layers of the eye’s surface,  the layers that are naturally shed every day. The researchers found that signs of corneal damage didn’t appear until exposure reached at least 3,500 mJ/cm², a level vastly higher than the TLVs. This “lowest observed adverse effect level” is over 150 times higher than the ICNIRP TLV of 23 mJ/cm (Kaidzu et al., 2021).
• Another study used a lab-grown human eye model to study DNA changes at different UV wavelengths. Their findings confirm that Far-UVC only causes minor effects in the very top layers of the corneal surface. Critically, no damage was observed in the deeper, regenerative cells that are essential for long-term eye health, even without the protective tear film (Buonanno et al., 2025).
• Finally, real-world data comes from a 3-year clinical study involving eye doctors working daily under filtered 222 nm Far-UVC lighting. Even after 36 months, no participants showed any signs of eye damage. Vision, corneal health, and eye cell counts remained unchanged, and no discomfort or delayed effects were observed (Sugihara et al.,2024).

After more than a decade of research, the science is clear: filtered Far-UVC light at 222 nm is safe for human exposure when used within the established guidelines. It doesn’t penetrate living skin or eye tissue and has consistently shown no harmful effects, even after long-term use. Whether in healthcare, cleanrooms, or public spaces, Far-UVC offers a promising way to reduce pathogens,  safely and continuously