Bactericidal Action of Ultraviolet Radiation on Air-Borne Organisms

Effect of Relative Humidity on the Inactivation of Airborne Serratia marcescens by Ultraviolet Radiation

“…3) confirm and extend the findings of Gates (5) and of Whisler (22) which showed a precipitous loss of UV sensitivity at RH values above 60%. Our data are not compatible with the work of Rentschler and Nagy who found no RH effect (13). These workers all used Escherichia coli aerosols.…”

“…In exploring the application of ultraviolet (UV) air disinfection in rooms for the purpose of reducing airborne infection (15)(16)(17)(18), it became apparent that more complete information is needed on the relationship between-relative humidity (RH) and the effectiveness of UV as an air disinfectant. Although a number of workers have reported decreased killing of airborne organisms by UV at humidities in excess of 60 to 70% (5,10,21,22), there are statements in the literature denying any RH effect (12)(13)(14). This controversy needs to be resolved both as a contribution to basic knowledge of the germicidal effects of UV and as a basis for predicting the effectiveness of UV installations under various conditions of RH.…”

PLOIDY STUDIES ON THE LARGE CELLS OF MICROCOCCUS AUREUS

“…The ultraviolet survival curve of a 4-day-old resistant culture was decidedly sigmoidal and was quite similar to the survival curve of large cells. Similar results were reported in M. albus, in which the ultraviolet survival curves of the resistant forms weie sigmoidal and the survival curves of the nonresistant forms were exponential (Rentschler and Nagy, 1942). Witkin (1947) reported that ultraviolet-resistant strains of E. coli strain B showed a sigmoidal survival curve in contrast to the exponential type curve for the nonresistant forms.…”

Environmental control for tuberculosis: basic upper-room ultraviolet germicidal irradiation guidelines for healthcare settings.

“…Several studies have examined the relationship between ambient RH and the effects of UVGI on airborne microorganisms. Two studies [Rentschler and Nagy 1942;Rentschler et al 1941] reported that RH did not have any effect on the ability of UVGI to kill or inactivate Esherichia coli. However, most reports [Gates 1929a;Ko et al 2000;Luckiesh and Holladay 1942;Miller et al 2002;Peccia 2000;Riley and Kaufman 1972;Wells 1942Wells , 1955Wells and Wells 1936] have indicated that UVGI effectiveness decreases as RH increases.…”