Experiments on terminal disinfection of cubicles with formaldehyde

Abstract

The conditions for satisfactory fumigation with formaldehyde were investigated using suspensions of Staph. aureus and Ps. aeruginosa dried as drops on strips of polythene or after mixing with cotton dust. In laboratory experiments with controlled concentrations of formaldehyde and water vapour, satisfactory results were obtained at 86 % humidity, but at 32 % humidity the formaldehyde was virtually inactive.Measurements under field conditions showed that the permanganate method of vaporizing formaldehyde did not vaporize enough water to produce optimum conditions for sterilization, and that great care was necessary in the sealing of rooms. When sterilization was incomplete the surviving organisms were not uniformly distributed within the room.In the limited circumstances in which fumigation with formaldehyde is thought to be essential, the process should be controlled by estimating the formaldehyde and water vapour concentrations initially and after 3 hr.