Evaluation of an automated far ultraviolet-C light technology for decontamination of surfaces and aerosolized viruses in bathrooms

Aerosols generated during toilet flushing are a potential source for transmission of viral and bacterial pathogens in bathrooms. However, manual decontamination of bathrooms after each use is not feasible.

We tested the efficacy of a wall-mounted far ultraviolet-C (UV-C) light technology that only delivers far UV-C when people are not present for decontamination of surfaces and aerosolized viral particles in an unoccupied hospital bathroom. A quantitative disk carrier test method was used to test efficacy against organisms on steel disk carriers placed in 9 sites in the bathroom with an exposure time of 45 min and 2 h; Clostridioides difficile spores were also exposed for 24 h. Efficacy against aerosolized bacteriophage MS2 was tested with a 45-minute exposure.

The far UV-C technology reduced methicillin-resistant Staphylococcus aureus (MRSA), vancomycin-resistant enterococci (VRE), Candida auris, and bacteriophage MS2 on steel disk carriers by ≥ 1.2 log₁₀ (range, 1.2 to 4.2 log₁₀) at all test sites after 2 h of exposure. The technology reduced C. difficile spores by < 1 log₁₀ after 2 h exposure, but 4 of 9 test locations had ≥ 2 log₁₀ reductions after 24 h exposure. Aerosolized bacteriophage MS2 was reduced by 4 log₁₀ plaque-forming units in 45 min.

The far UV-C light technology could potentially be useful for automated decontamination of air and surfaces in bathrooms in healthcare and community settings.