USING FACE MASKS IN THE CLASSROOM: THE EFFECT ON THE INDOOR ENVIRONMENT PARAMETERS AND FACE THERMOPHYSIOLOGICAL REACTIONS

Masks have been recommended as a protective tool for effectively combating the COVID-19 pandemic. In many countries, masks are required indoors, but the obligation temporarily and sporadically extends to all public places indoors and outdoors in some regions. Our study investigated the effect of wearing face masks in the classroom on the indoor environmental parameters and the human body experimentally. The study was performed at the Technical University of Sofia with 14 volunteers during regular lecture classes. Two stages were considered: with and without face masks. Measurement of the indoor environment parameters, oxygen (O-2) and carbon dioxide (CO2) concentration was continuously performed. Thermal image analysis was used to obtain the face thermograms of the participants. The results clearly showed the retention effect of the face masks on the exhaled air, leading to lower CO2 concentration in the classroom and higher O-2 concentration and humidity. It was also found that the continuous wear of a face mask for 40-45 min provoked an increment of the facial skin temperature under the mask to 37 degrees CC and even more. The rise of the temperature of the inner cantus of the eye showed that the face mask triggered the body's thermoregulation, causing thermophysiological reactions.