In the table, R is the reduction in viral load, C is an average of TCID₅₀ of the positive control groups, andT is the TCID₅₀ values of the test groups. The residence time of the air was 1.44 seconds at the air flow rate of 0.6 m³/h in the heater with a cross-section area of 4x4 cm² and length of 15 cm. During this time, the air temperature increased from 20 ^oC to 150^oC or 220 ^oC.

An analytical model based on the rate law for a first-order reaction and the Arrhenius equation was used to determine the temperature dependence of the rate constant and estimate the time required to inactivate SARS-CoV-2(Hessling et al., 2020; Yap et al., 2020) . The rate constantk (T ) for thermal inactivation of both SARS-CoV-2 and SARS-CoV was obtained(Hessling et al., 2020). Using the same data, we calculated the inactivation time 0.320 s for 3 log₁₀reductions at 150 ^oC and 0.007 s for 5 log₁₀ reductions at 220 ^oC in the viral load. The residence time of the virus in the heater is 4.5 times and 205 times longer than the calculated time needed to inactivate the virus at the temperature of 150 ^oC and 220^oC. The approach of using the heater outlet temperature as a reference is reasonable since the estimated times for inactivation of the viruses are a fraction of a second and much smaller the residence time for the selected temperatures.

4 | CONCLUSION

Our results show that high-temperature is very effective in inactivating aerosolized SARS-CoV-2 within a second. It can be implemented primarily during winter, just by increasing the heater’s temperature to 150^oC or above for a fraction of a second to provide 3 log₁₀ reductions in the viral load of SARS-CoV-2 in air. It has the potential to be used in houses, hospitals, shopping centers, HVAC (heating, ventilating, and air conditioning) systems, and public transport vehicles during winter.