The condition of air quality depends on many external (the amount of pollutant emissions, intensity and type of physico-chemical changes taking place in the atmosphere and large-scale movement of air pollutant masses) as well as internal factors (such as finishing materials, room equipment, heating systems, ventilation systems, and the presence of the humans themselves). As a result, there are various risks related to air quality, including the most important ones related to microbial contamination. For this reason, it was decided to analyze the quality of internal air in terms of microbiological contamination that may occur in university lecture halls with mechanical supply and exhaust ventilation. The analysis also took into account the impact of mechanical ventilation on physical parameters such as temperature, relative humidity as well as the concentration of PM10 and PM2.5 particulate matter pollutants, thus determining the impact of the tested parameters on human health and well-being. All the obtained results were compared with the applicable permissible standards and conclusions were drawn regarding the improvement of the quality of the indoor air microclimate.