Effect of Relative Humidity on Formaldehyde Decontamination

Formaldehyde gas inactivation ofBacillus anthracis,Bacillus subtilis, andGeobacillus stearothermophilusspores on indoor surface materials

“…These results suggest that when using the decontamination parameters outlined in this study, material porosity did not appear to affect decontamination efficacy of formaldehyde gas. As with previous studies (Braswell et al 1970;Hoffman and Spiner 1970;Spiner and Hoffman 1971;Sweet 1971;Ackland et al 1980;Canter et al 2005), a similar starting paraformaldehyde concentration (10AE5 g per cubic meter) was used in this study to yield a theoretical vapor phase concentration of approx. 8500 ppm formaldehyde gas in the decontamination chamber.…”

“…Methods for producing spores could vary between laboratories and differences in incubation temperature and growth medium can influence spore resistance to decontamination (Palop et al 1999;Cazemier et al 2001;Melly et al 2002b). The presence or absence of debris in spore preparations can also influence the rate at which formaldehyde gas inactivates spores, especially on nonporous surfaces (Spiner and Hoffman 1971). However, the spore preparations used in this study exhibited little to no debris and greater than 95% spore refractility under phase contrast microscopy, suggesting the effect of spore cleanliness on formaldehyde decontamination in this study was probably not a factor.…”

“…Temperature, relative humidity, formaldehyde concentration, and formaldehyde adsorption onto surfaces are crucial factors contributing to the sporicidal activity of formaldehyde gas (vapor phase equilibrium concentration of formaldehyde; Munro et al 1999). Formaldehyde gas sporicidal efficacy is directly proportional to its concentration at a relative humidity greater than 50% (Spiner and Hoffman 1971). Munro et al (1999) showed that the optimal decontamination conditions for Bacillus spores, M. bovis, and poliovirus were 66% relative humidity, a minimum temperature of 28°C, and 10AE5 g paraformaldehyde ⁄ m 3 (theoretical concentration of 8500 ppm).…”

Pharmaceutical Sciences—1972: Literature Review of Pharmaceutics I‡‡Editor's note: Part I1 of this article will appear in the August 1973 issue of the Journal of Pharmaceutical Sciences.

“…were essential for the sterilization of spore-contaminated materials using formaldehyde (293). The history and an extensive review of the use of radiation methods for the sterilization of drugs were presented (294).…”

The effects of controlled exposure to formaldehyde vapour on spores of Bacillus globigii NCTC 10073

“…The most detailed study of the effects of formaldehyde vapour was carried out by Nordgren (1938) who used a specially constructed apparatus supplied with formaldehyde vapour from a separate generator. The method most commonly used (Braswell et Spiner & Hoffman 1971) is to carry out the test exposures in small containers into which a known amount of formaldehyde is introduced. It is not normally possible, however, to measure the conditions within these containers since the removal of air samples for analysis will change them.…”