Germicidal mists and vapours in air disinfection

Baker, A. H.; Twort, C. C.

doi:10.1017/s0022172400013139

Cited by 8 publications

(5 citation statements)

References 5 publications

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“…The methods described by them utilize the following principles for collection of particles from the air: (1) thermal precipitation, (2) filtration, (3) electrical precipitation, and (4) impingement. (5) In addition, we seriously considered a direct count of particles containing radioactive materials by means of a Geiger counter. ( 6) Use of an electrostatic counter devised by Guyton (41) appeared unsuitable, since it is not sufficiently sensitive (39).…”

Section: A Introductionmentioning

confidence: 99%

“…This method was therefore used for appraising the photoelectronic counter. (5) We seriously considered the use of a Geiger counter to count particles containing radioactive material. Specious counts due to the presence of minute radioactive particles outside the bacteria were possible, and proof of their absence seemed difficult.…”

Section: A Introductionmentioning

confidence: 99%

“…None the less, epidemiological investigations of the more common respiratory diseases such as pulmonary tuberculosis (1), influenza, and the common cold demonstrate the importance of airborne agents (16). On this basis, air sterilization by ultraviolet light (27,57) or by chemical agents (4,5,15,26,28,29,31,42,54,60,70,71,72,74,75,87,88) has been applied to their control. These methods will not be reviewed here.…”

mentioning

confidence: 99%

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The Preparation and Measurement of the Concentration of Dilute Bacterial Aerosols.

Ferry¹,

Farr²,

Hartman³

1949

Chem. Rev.

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Section: A Introductionmentioning

confidence: 99%

Section: A Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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The Preparation and Measurement of the Concentration of Dilute Bacterial Aerosols.

Ferry¹,

Farr²,

Hartman³

1949

Chem. Rev.

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“…DISCUSSION Experimental results which are consistent with the thesis that aerial disinfectants operate through the medium of the vapor phase have been reported by several investigators (12,14,26). Those of Baker and Twort (27) are worthy of mention. Recently they repeated our demonstration (28,29) that pure vapors produced by evaporation from exposed liquid surfaces are rapidly lethal toward air-borne bacteria, and succeeded in obtaining excellent results with compounds like phenol, and chlorthymol for which their earlier reports had claimed activity only when dispersed as aerosols, but not as vapors (30).…”

Section: Effect Of Temperature Changes At Constant Relative Hura~ditymentioning

confidence: 94%

The Mechanism of Aerial Disinfection by Glycols and Other Chemical Agents

Puck

1947

Journal of Experimental Medicine

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The effectiveness of any compound as an aerial germicide depends upon the extent of condensation of its vapor on air-suspended bacteria, and on the rate at which the resulting concentration of germicide can produce death of the microorganisms. The properties of any compound conducive to production of the highest rate of kill of air-borne microorganisms by means of the smallest possible concentration of germicide vapor, are as folows: (a) a low vapor pressure, but not lower than 0.001 mm. Hg at 25°C.; (b) high hygroscopicity; (c) toxicity for bacterial metabolism—a high degree of potency is not necessary although the killing action will be more efficient the higher the antibacterial activity of the compound employed. For any compound the killing action is always a direct function of the concentration of its vapor in the air. The maximum amount of a hygroscopic substance which can exist in the vapor state decreases as the relative humidity increases. Hence, at high relative humidities the bactericidal efficiency is lowest. At lower relative humidities the air can contain more vapor, and hence a greater effect is possible. At any relative humidity, the killing action is greater, the more closely the germicide vapor concentration approaches the saturation point. The presence of soluble compounds in droplets containing bacteria promotes more extensive condensation of the germicide than would otherwise occur, and so enhances its effectiveness. In the absence of such soluble substances, low atmospheric humidities may cause complete desiccation of a bacterial particle. Under these conditions its surface may become resistant to the condensation of the vapor, and thus prevent effective germicidal action. The influence of temperature changes on the killing efficiency maybe correctly deduced from a consideration of the effect of a rise in temperature on the vapor pressure of the germicide and on the rate of its bactericidal action in vitro. Equations are presented for estimating quantitatively the magnitude of some of the effects discussed.

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“…The atomization of various mixtures has been recommended and diverse effects dealing with the relationship of bactericidal efficiency to the persistence of such aerosol mists, have been ascribed to the relative humidity and the temperature of the atmosphere, and the vapor pressure and hygroscopicity of the components of the solutions nebulized (12,18,25,28,29). However, it is not possible to secure from any of these data, a dear explanation for the action of these factors nor to predict accurately how any particular alteration in either the environmental conditions or the composition of the substance employed as the disinfectant, will affect the bactericidal efficiency.…”

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confidence: 99%

The Mechanism of Aerial Disinfection by Glycols and Other Chemical Agents

Puck

1947

Journal of Experimental Medicine

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Theoretical analysis of the mechanism of action of chemical aerial disinfectants reveals that the rapid killing action which is obtained cannot be accounted for by a collision process between germicidal aerosol particles and the air-borne bacteria. However, a mechanism involving condensation of germicide molecules in the vapor state on to the bacteria-containing droplets results in a theoretical velocity of the correct order of magnitude. Experimental tests of this theory show that pure germicide vapors free of aerosol droplets are almost instantly lethal to air-borne bacteria. Conversely, pure germicidal aerosols in the absence of vapor, had no effect on air-borne bacteria within 20 minutes or more. Therefore, it may be concluded on both theoretical and experimental grounds that rapid air sterilization requires the existence of the germicide in the vapor state.

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Germicidal mists and vapours in air disinfection

Cited by 8 publications

References 5 publications

The Preparation and Measurement of the Concentration of Dilute Bacterial Aerosols.

The Preparation and Measurement of the Concentration of Dilute Bacterial Aerosols.

The Mechanism of Aerial Disinfection by Glycols and Other Chemical Agents

The Mechanism of Aerial Disinfection by Glycols and Other Chemical Agents

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