Mathematical modeling of ultraviolet germicidal irradiation for air disinfection

Abstract. A comprehensive treatment of the mathematical basis for modeling the disinfection process for air using ultraviolet germicidal irradiation (UVGI). A complete mathematical description of the survival curve is developed that incorporates both a two stage inactivation curve and a shoulder. A methodology for the evaluation of the three-dimensional intensity fields around UV lamps and within reflective enclosures is summarized that will enable determination of the UV dose absorbed by aerosolized microbes. The results of past UVGI studies on airborne pathogens are tabulated. The airborne rate constant for Bacillus subtilis is confirmed based on results of an independent test. A re-evaluation of data from several previous studies demonstrates the application of the shoulder and two-stage models. The methods presented here will enable accurate interpretation of experimental results involving aerosolized microorganisms exposed to UVGI and associated relative humidity effects Key words: UVGI, UV air disinfection, surface disinfection, survival curve, decay curve 1