Effect of relative humidity on the stability of Mycoplasma pneumoniae exposed to simulated solar ultraviolet and to visible radiation

Abstract

Airborne Mycoplasma pneumoniae was exposed to near ultraviolet (3000–4000 Å) light, daylight fluorescent light, or total darkness at 25%, 50%, or 95% relative humidity. Without light, survival of the organisms was good at both high and low R.H. with poorest survival occurring at 50% R.H. The effect of ultraviolet light was to decrease the survival of airborne organisms at all R.H. levels, but was most dramatically seen at 25%. The high (95%) R.H. appeared to provide some protection against ultraviolet damage. The relationship between R.H. and ultraviolet light to survival was a second order reaction and supports the theory of indirect, possibly multiple site, injury that results from ultraviolet radiation. The possibility of using a combination of conditions deleterious to survival of airborne M. pneumoniae as a means of epidemiologic control is discussed.