The Mechanism of Aerial Disinfection by Glycols and Other Chemical Agents I. Demonstration That the Germicidal Action Occurs

In a series of publications which have appeared during the last five years (1-8), the activity of certain organic compounds, particularly propylene and triethylene glycols, in killing air-borne bacteria and viruses has been described. The types of microorganisms found to be susceptible and some effects on this killing action of changes in the temperature, relative humidity, and concentration of the bactericidal agent, have been presented. An hypothesis was advanced to account for these observations, namely, that the lethal effect is due to condensation of vapor molecules of the active agent on to the bacteriacontaining particles so that a bactericidal concentration of the germicide accumulates about the microorganisms. Some of the evidence in support of this theory has been briefly described in preliminary reports from this laboratory (3, 4, 9), and additional confirmation has since been presented by other investigators (10-12). It is the purpose of the present paper to give a detailed account of the experimental evidence which demonstrated the validity of this mechanism. :In subsequent publications some of the factors which govern the attainment of effective contact between molecules of the germicide and air-borne microorganisms will be developed (13) and studies on the metabolic character of the killing process by some specific aerial bactericides witl be presented (14). Killing of air-borne bacteria has been reported to occur through the action of a number of chemical agents, for example, phenol (15), NaOC1 solutions (16, 17), resorcin01 and n-hexyl resorcinol (18). 1 All of these compounds, however, are powerful bactericidal agents in viiro. The demonstration that propylene and triethylene glycols are effective in the air even in very great dilution revealed that it is not essential for an aerial disinfectant to be a powerful inhibitor