Effectiveness of UV Radiation for reducing Aspergillus niger and Actynomices contamination in air-conditioning systems.

The effectiveness of UV radiation lamps in order to reduce fungal contamination of HEPA filters, to extend filter efficacy and to reduce maintenance costs, is experimentally studied by means of a dedicated air conditioning unit. An experimental HVAC system, with HEPA filters and UV-C lamps (lambda=254 nm), was built. Two experiments were performed. After disinfection and control of airtightness, the internal surface of the HVAC system was contaminated (1) with A. niger spores and (2) with Actynomices. Temperature level was 300 K and Relative Humidity (RH) ranged from 30-90%. The results show that the addition of UV-C lamps to HVAC system reduces A. niger and Actynomices air concentrations; the effectiveness increases with the decrease of RH level in the HVAC system.