Verification and Challenges of Dry Mist and Vaporized H ₂ O ₂ Disinfection in Space and HEPA Unit in BSL-3

The disinfection of high - level bio-safety laboratories poses challenges in terms of personnel safety, disinfection efficacy, and corrosiveness to items. In this study, whole- room disinfection of BSL-3 using a dry mist H 2 O 2 generator and a vaporized H 2 O 2 generator, as well as dry mist disinfection of HEPA exhaust, were proposed. A dry-mist H 2 O 2 generator and a vaporized H 2 O 2 generator were applied individually to disinfect the space of the BSL-3, along with BSC and HEPA unit. Spores of B. subtilis var. niger and B. stearothermophilus were applied as biological indicators to conduct a qualitative assessment of the disinfection efficacy. The dry- mist H 2 O 2 generator, utilizing a 10% H 2 O 2 solution at a dosage of 10 mL/m³ and with a disinfection duration of 3h, achieved a killing logarithm of 5- 6 log10 for the two types of spores. The identical efficacy was achieved for the vaporized H 2 O 2 generator, by 35% H 2 O 2 at a dosage of 6.5 mL/m³ and with a residual duration of 3h. The disinfection of the exhaust HEPA verification port using 10% dry-mist H 2 O 2 presented significant challenges. All spores were capable of being inactivated when the port was uncovered; while the inactivation of all spores was not achieved when the port was covered. Dry mist H 2 O 2 and vaporized H 2 O 2 disinfection methods demonstrated stable spatial disinfection effect on B. subtilis var. niger and B. stearothermophilus . Achieving the disinfection effect at the disinfection verification port of the HEPA exhaust for the dry mist H 2 O 2 disinfection poses a significant challenge.