What is 222nm Far-UVC?
A new category of light that kills airborne pathogens — while being safe for people in the room.
Not all UV light is the same
Ultraviolet light exists on a spectrum. Conventional germicidal UV (254nm) is highly effective at killing pathogens — but it's also dangerous to human skin and eyes, which is why it can only be used in empty rooms.
222nm Far-UVC is different. At this specific wavelength, the light is absorbed by proteins in the outermost layer of human skin and the tear layer of the eye before it can cause damage. But bacteria, viruses, and other microorganisms — which are far smaller — are penetrated and destroyed.
This creates a unique window: effective disinfection that can happen continuously, in occupied spaces, without harming the people inside.
Why 222nm is safe for people
The key is penetration depth. 222nm light has a very short mean free path in biological tissue — it's completely absorbed within the outermost dead cell layer of skin (the stratum corneum) and the aqueous layer of the eye.
It simply cannot reach living cells. This has been confirmed in multiple peer-reviewed studies, including a landmark 66-week chronic exposure study at Columbia University that found no evidence of skin cancer or abnormalities after continuous 222nm exposure.
ACGIH / ICNIRP Safety Limits at 222nm
Well-designed 222nm devices operate well within these limits during normal use.
What it kills — and how well
222nm Far-UVC has demonstrated efficacy against a broad spectrum of airborne pathogens in peer-reviewed research:
- SARS-CoV-2 (COVID-19) — 99.9%+ inactivation in room-sized chamber studies
- Influenza A (H1N1) — effectively inactivated at low doses
- Drug-resistant bacteria (MRSA, C. auris) — proven efficacy against antibiotic-resistant strains
- Tuberculosis (M. tuberculosis) — inactivated at clinically relevant doses in aerosol studies
- RSV and common cold viruses — broad-spectrum effectiveness across respiratory pathogens
- Seasonal coronaviruses — demonstrated inactivation consistent with other enveloped viruses
The mechanism is the same as all UV disinfection: photons damage the nucleic acids (DNA/RNA) of microorganisms, preventing replication. At 222nm, this happens efficiently because pathogens lack the thick protein coat that protects human cells.
Key research institutions
The science behind 222nm Far-UVC has been developed and validated by leading research institutions over the past decade:
"Far-UVC light at 222nm efficiently inactivates airborne human coronaviruses while remaining safe for direct human exposure."— Nature Scientific Reports, Columbia University Irving Medical Center (2020)
Ready to learn more?
Browse member stories from people using 222nm devices in homes, offices, schools, and clinics — or explore our curated device directory.