SARS-CoV-2 inactivation on hard non-porous airplane cabin material surfaces was limited after exposure to far UV-C (222 nm) radiation.

Aims To test the efficacy of 222 nm far UV-C for surface disinfection of SARS-CoV-2 on inanimate surfaces from airplane cabins. Methods and results Two far ultraviolet (UV-C) irradiation light systems were evaluated for disinfection of SARS-CoV-2. Materials used for carriers (test surfaces) included polished stainless steel and used airplane materials, including seat belt latches, window dust covers, sidewall laminates, and tray tables. Conclusions While demonstrating reasonable efficacy under some experimental conditions, the data indicated that 222 nm far UV-C disinfection alone does not reliably provide a 3 log₁₀ or 99.9% reduction of SARS-CoV-2 on inanimate surfaces from an airplane cabin. An Ushio (Cypress, CA) 1.7″ × 2.3″ Care222^® 12 W 222 nm BI lamp module tested in triplicate at a low (⁓1.5 mJ cm⁻²), medium (⁓3.0 mJ cm⁻²), and high (⁓6–9 mJ cm⁻²) fluence did not provide a ≥3 log₁₀ or 99.9% reduction of SARS-CoV-2. The reduction of SARS-CoV-2 was greatest on stainless steel. The result was a log₁₀ reduction of 2.83, 1.33, 2.58, and 2.21 logs for virus samples containing saline, saline with 2.5 mg BSA, saline with 0.25 mg BSA, and artificial saliva, respectively, at a dosage of 5–9 mJ cm⁻². The log₁₀ reduction of SARS-CoV-2 in saline with 2.5 mg bovine serum albumin was lowest with 1.33 for stainless steel, 0.93 for belt latch, and 0.61 for tray table at a dosage of 5–6 mJ cm⁻². The second UV lighting system tested was a prototype mobile wand with a built-in short-pass filtered krypton-chloride cylindrical lamp. One pass of the wand over a tray holding carriers inoculated with SARS-CoV-2 in artificial saliva at a rate of ∼1 foot (1′) per second exposed the carriers to 7.3 mJ cm⁻². The log₁₀ reductions determined for the single pass were 2.97, 3.75, 1.78, 1.91, and 1.28 logs for stainless steel, belt latch, dust cover, sidewall, and tray table, respectively. Two passes of the wand generated 17.2 mJ cm⁻² and resulted in log₁₀ reductions of 4.04, 3.74, 4.24, 3.68, and 1.66 logs for stainless steel, belt latch, dust cover, sidewall, and tray table, respectively. The combination of higher fluence from multiple passes of the wand, the close proximity (10 cm wand to the carrier), the exposure to elevated temperatures up to 35°C, and ozone from the bulb being blown directly onto the carriers contributed to effective viral inactivation on all surfaces except the airplane tray table. The impact of temperature and ozone on viral inactivation should be determined for future testing of the 222 nm UV-C wand. [ABSTRACT FROM AUTHOR]