Efficacy and safety of 222-nm far-UVC radiation in humans and occupied spaces: a systematic review

Objective. To characterize evidence on skin, ocular, microbiological and clinical effects of 222-nm far-UVC in humans and occupied spaces, considering exposure and study design.

Methods. Retrospective systematic review of human and environmental evidence, with a main cutoff of 6 September 2026 and targeted updates through 27 September. The inventory contains 2,552 records. Design, exposure, comparator, outcomes and denominators were extracted with AI assistance and human review of study selection and data extraction. Published adjusted coefficients were retained and exact study-level intervals calculated, without meta-analysis.

Results. Seventeen human and 13 environmental reports were included; two additional environmental reports and seven candidate groups did not contribute to the main synthesis because documentation was insufficient. Human reports represented 16 study families and 1,145 recruitments, including controls. In the wound trial, adjusted day-15 interactions favored wound status (PSST: β −4.79; 95% CI −7.29 to −2.29) and bioburden (β −2,214.33 CFU/mL; −4,303.54 to −125.13); the confidence interval for wound area included zero (β −11.06 cm²; −22.19 to 0.07; p=0.051). Some ocular regimens produced discomfort and superficial findings. Registry D17 yielded no DNA-damage data. E15 reported surface-bioburden reductions, with statistical differences in four of five surface types.

Conclusions. The synthesis identifies antimicrobial activity of 222-nm far-UVC and favorable adjusted PSST and bioburden outcomes in one wound trial; the day-15 wound-area effect was uncertain. Its contribution is to link each result and adverse effect to exposure, study design and its denominator. Findings apply to the conditions studied and do not establish causal prevention of infections or universal or long-term safety.