Methods for Indoor Air Disinfection and Purification from Airborne Pathogens for Application in Hvac Systems

The present paper is a review on methods and technologies for air cleaning from micro organisms and viruses, which are applicable with the present HVAC practices. The advantages and the drawbacks of air dilution, filtration (HEPA, ULPA), ultraviolet germicidal irradiation (UVGI), photocatalytic oxidation (PCO), plasmacluster ions and other technologies for air disinfection and purification is critically analyzed with respect to the used today air distribution principles. The importance of indoor air characteristics, such as temperature, relative humidity and velocity on the efficiency of the methods is analyzed with consideration of nature of the pathogens themselves. Recent encouraging studies show the benefit of using essential oils as antimicrobial and anti-fungal agents (thyme, bay, cinnamon, clove, etc.). Though their application is confined to the food industry and pharmaceutics, some promising results show possible applicability in the field of ventilation and air conditioning to deactivate the airborne micro-organisms. The applicability of the methods with different types of ventilation used at present indoors, i.e. total volume ventilation (mixing and displacement), as well as advanced air distribution techniques (such as personalized ventilation) is discussed.