Thermal Inactivation of Airborne SARS-CoV-2 by an Electric Fan Heater in Winter and Defining Conditions to Ensure That All the Air Passes Through the Fan

Abstract The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is spread, especially in closed environments, by airborne transmission. The study aims to assess the thermal inactivation of airborne SARS-CoV-2 in a 30 m3 test room as a function of outlet temperature, airflow rate, and operating time of an electric heater, then define a condition to ensure that all air in the room passes through the electric heater. Aerosolized SARS-CoV-2 was delivered to the test room at an ambient temperature of 20 °C and 40% humidity. Two electric heaters with different powers and airflow rates were operated respectively in the test room to compare their efficiencies in the inactivation of airborne SARS-CoV-2. The first and second electric heaters had power, airflow rates, and outlet temperatures of 1.5 kW, 44 m3/h, 220 °C, and 3 kW, 324 m3/h, and 150 °C, respectively. A fan drew the outside air into the heater. In the first experiment, a 1.5 kW electric heater was operated in the test room for 80 min. In the second experiment, a 3 kW electric heater was used in the test room for 75 min. Airborne SARS-CoV-2 in the test room was inactivated by 99.00% and 99.96% in the first and second experiments, respectively. A condition is defined to ensure that all the air in the room passes at least once through the electric heater fan.