Disinfection of Simulated Residual SARS-CoV-2 in Air by Chlorine Dioxide Gas in an Ambulance Setting.

Introduction: Disinfecting contaminated ambulances presents a challenge to emergency medical services. The process relies on a manual cleaning step or the use of foggers and gas generators. Equipment requires training, power supply, and access to reagent refills. Chlorine dioxide (ClO2) gas is an affordable, easy-to-use alternative. Methods: We field-tested ClO2 dry inside an ambulance against a surrogate for SARS-CoV-2. MS2 bacteriophage was aerosolized inside of an enclosed. Airborne MS2 concentrations were measured before and after ClO2 applications to compare reductions in viable virus. ClO2 gas was generated using ICA-TriNova UltraShok™ 2-part media in different concentrations and time courses. Petri dishes were used to determine the surface deposition of residual MS2 phage. ClO2 gas was monitored using a PortaSens III gas detector with high and low range sensors. Results: MS2 bacteriophage measured at 15-min averaged 99.99% in both 100 g and 130 g applications, compared to 83.48% in controls. At 60-min, air MS2 percent reductions averaged 99.99% in 100 g applications compared to 98.05% in controls. Mean surface MS2 counts within protocols using ClO2 gas ranged from 245 to 5110 plaque-forming unit (PFU)/petri-dish compared to 13,900-44,900 PFU/petri-dish in controls. ClO2 gas concentrations fell below OSHA 15-min short-term exposure limit of 0.3 PPM within 5 min of passive ventilation in all tests. There were no observed detrimental impacts on materials and surfaces. Conclusion: ClO2 gas produced using ICA-TriNova UltraShok™ 2-part media is an effective air disinfection technique for contaminated ambulance settings. Integration with manual cleaning permits safe, rapid decontamination of ambulance vehicles.