Bactericidal effects of the partial irradiation of a room with ultra-violet light

Abstract

The process of removal of bacteria from the air of a room of which part only is irradiated with ultra-violet light is discussed.Formulae are derived for the rate of disappearance of bacteria from the air in such circumstances and for The equilibrium levels reached when bacteria-carrying particles are being continuously introduced into the air at a constant rate. These formulae include terms for the effect of simultaneous ventilation and for the effect of sedimentation of the bacteria-carrying particles.The results of a short series of tests are compared with those calculated from these formulae and the two found to agree reasonably well on the assumption that the air within both the irradiated and nonirradiated zones is effectively mixed.Figures are given over a range of humidities for the sensitivity of salivary organisms to ultra-violet irradiation when suspended as small particles in the air.A chart is presented for the evaluation of the mean radiation intensity within a rectangular volume produced by a point source situated within or on the boundaries of the volume.