Simplified Model of Humidity in the Space of a Protective Mask and Experimental Verification—A Pilot Study

Air humidity is an important parameter of the microclimate in the mask space. The aim of the study is to assess the mask microclimate in terms of air humidity and to develop a simplified model of humidity distribution as a function of time, which can be used to estimate and predict humidity in the mask space. Humidity and temperature parameters were tested for five different types of protective masks. The protective masks used for the tests differed in their construction and material thickness of the mask walls. The microclimate in the mask space was assessed based on one-hour measurements of temperature and humidity during office work, based on publicly available guidelines and standards. Based on the moisture balance in the space between the face and the mask wall, a simplified one-dimensional model of absolute humidity in space was determined. The results of the study indicated that in all cases, regardless of the type of mask, the permissible values of temperature and relative humidity were exceeded. The average values of temperature and relative humidity in the mask space for all masks and people were 31.94 °C and 83.65%, respectively. The absolute humidity value is strongly dependent on the ambient air humidity. In months with higher absolute humidity values, such as September, a higher absolute humidity occurs in the mask space. One way to lower the humidity level in the mask is to dry the air in the room.