Why Far-UVC Can Be Used in Occupied Spaces

Far-UVC light (typically at 222 nm) is an effective disinfection technology that can inactivate microorganisms and is designed for use in occupied spaces when applied within established exposure limits

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 use in occupied spaces, 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) limits its penetration beyond the stratum corneum (the outer dead-cell layer of skin) or the tear film and outermost corneal layer of the eye. This absorption significantly limits Far-UVC penetration into deeper, living cells where biological 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 did not show observable burns or clinically apparent skin damage under the conditions tested. Only at very high doses (above 6000 mJ/cm) did a faint yellowing occur, which faded within hours. Tests confirmed that the effect was limited to superficial layers and was not observed to affect deeper living skin tissue (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 has not been shown to cause tissue damage in the studied conditions, 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 did not observe an increase in skin tumors, unusual growths, or tissue changes compared to non-irradiated control mice (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 were observed under the study conditions with repeated 222 nm exposure (Yamano et al., 2020).
• A third study looked for cumulative damage from repeated high doses of Far-UVC light. The researchers observed no skin abnormalities or DNA lesions under the study conditions, supporting the view that filtered Far-UVC is suitable for repeated use when applied within established exposure limits (Narita et al., 2018).

A growing body of evidence demonstrates that filtered 222 nm Far-UVC light can provide effective disinfection, with studies not reporting harmful skin effects under the tested conditions, including in longer-term exposure scenarios.

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 when used within established safety limits, 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 observed no signs of corneal damage under the tested experimental conditions. Signs of damage were only observed at exposure levels of 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 signs of eye damage were reported or detected among participants during the study period. 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 can be used in occupied environments when operated within established safety guidelines. It has been shown to have limited penetration into living skin and eye tissue and  has not demonstrated harmful effects in the controlled studies conducted to date. Whether in healthcare, cleanrooms, or public spaces, Far-UVC offers a promising way to reduce pathogens in occupied spaces.