Inactivation of viruses on surfaces by infrared techniques

Several studies on vaccines and medicines against virus-based illnesses (COVID-19, SARS, MERS) are being conducted worldwide. However, virus mutation is an issue. Therefore, inactivation and disinfection of viruses are crucial. This paper presents a method for virus inactivation by physical techniques. The infrared (IR) technique is preferred over other disinfection techniques such as ultraviolet (UV) and chemical disinfectants (alcohol) due to the associated health and environmental benefits. In this study, IR sources with various wavelengths were characterized and a far infrared (FIR) source was used to inactivate viruses. FIR sources have a therapeutic effect on the human body and have been used in medical centers. Virus spread is highly affected by environmental conditions such as temperature, humidity, and airflow. A setup with IR sources, an IR camera, an automatically controlled humidity chamber, and an airflow unit was constructed to study the viability of viruses in stationary droplets as a function of relative humidity and temperature. Bacteriophage Phi6 was used as a model organism for studying enveloped viruses such as influenza and coronavirus. IR techniques were used for studying virus inactivation. The effect of various physical conditions such as temperature, humidity, and airflows was considered to study the effect of radiation on the stationary droplets of Phi6. All measurements were performed under laboratory conditions with controlled temperature and humidity. The IR camera system was used to measure the surface temperature of Phi6 suspension droplets. The samples subjected to IR radiation were processed for plaque assay preparation and counting. Measurements were carried out to reduce and eliminate droplets, which are one of the transmission pathways of viruses. IR was radiated in closed and open-air conditions with appropriate humidity and temperature. This study reports the effective inactivation of viruses by FIR. The inactivation rate under 50 %rh for IR radiated at 1.4 m height for 3 h in closed environmental chamber was 90%, and that under an airflow rate of 0.20 m/s for 10 min in open-air conditions at a height of 1.0 m was 45.7%.