Measurement of Sanitary Ventilation

Wells, W. F.; Wells, Mildred Weeks

doi:10.2105/ajph.28.3.343

Cited by 31 publications

(10 citation statements)

References 2 publications

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“…For three of the experiments (BS-d1, BS-d2, and BS-d3, Table 1), a decay method similar to that of Riley et al (1976) and Wells and Wells (1938) was used.…”

Section: Test Protocolmentioning

confidence: 99%

“…We investigated two experimental designs, a steadystate and a decay method, similar to approaches others have used to study the effect of UVGI (Wells and Wells 1938;Riley et al 1976). We designed, equipped, and characterized a chamber with two wall-mounted germicidal lamps, a bacterial aerosol generation system, a ventilation system, and multiple air sampling locations.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Miller¹,

Macher²

2000

Aerosol Science and Technology

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ABSTRACT. As a result of the recent resurgence in tuberculosis (TB) and the increasing incidence of multidrug-resistant TB, there has been renewed interest in engineering controls to reduce the spread of TB and other airborne infectious diseases in high-risk settings. Techniques such as the use of lamps that produce ultraviolet germicidal radiation may reduce exposure to infectious agents by inactivating or killing microorganisms while they are airborne. We designed and evaluated a test method to quantitatively estimate the ef cacy of germicidal lamps, in conjunction with dilution ventilation, for reducing the concentration of viable airborne bacteria. Bacterial particles were generated in a 36 m 3 room and collected with midget impingers at 5 -7 locations. The effectiveness of the control technique was determined by comparing concentrations of culturable airborne bacteria with and without the control in operation. Results for a single, 15 W germicidal lamp showed reductions of 50% for Bacillus subtilis (B. subtilis) and Micrococcus luteus (M. luteus); tests with Escherichia coli (E. coli) showed nearly 100% reduction (E. coli were isolated only from the sampler nearest the aerosol source when the lamp was operating). The addition of louvers to a lamp greatly reduced its ef cacy. Decay experiments showed that roughly 4 -6 equivalent air changes per hour were achieved for B. subtilis with one or two lamps operating. These preliminary experiments demonstrated that this methodology was well suited for these evaluations and identi ed factors that could be modi ed to re ne the study design for future work.

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“…For three of the experiments (BS-d1, BS-d2, and BS-d3, Table 1), a decay method similar to that of Riley et al (1976) and Wells and Wells (1938) was used.…”

Section: Test Protocolmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Miller¹,

Macher²

2000

Aerosol Science and Technology

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“…In the early part of the last century, Wells and Wells (1938) showed that during coughing and sneezing, small microorganism-containing droplets were released into the air and that these droplets could evaporate and remain suspended in the air. Transmission of tuberculosis by inhalation of airborne Mycobacterium tuberculosis aerosolized by coughing has been well documented (Barnes et al 1996;Valway et al 1998).…”

Section: Introductionmentioning

confidence: 99%

Particle Image Velocimetry of Human Cough

VanSciver

Miller

Hertzberg

2011

Aerosol Science and Technology

109

113

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Cough generated infectious aerosols are of interest while developing strategies for the mitigation of disease risks ranging from the common cold to SARS. In this work, the velocity field of human cough was measured using particle image velocimetry (PIV). The project subjects (total 29) coughed into an enclosure seeded with stage fog. Cough flow velocity profiles, average widths of the cough jet, and maximum cough velocities were measured. Maximum cough velocities ranged from 1.5 m/s to 28.8 m/s. The average width of all coughs ranged between 35 to 45 mm. Wide variability in the data suggests that future cough simulations consider a range of conditions.

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“…causing a large number of diseases. 1 The droplets containing pathogens 2 can transmit from an infected individual to a healthy one in several ways, 3 such as through the respiratory system in the form of droplets or aerosols or via direct contact (touching a contaminated hand rail, a hand shake, etc.). The determination of the abundance of viruses in air, 4 their effectiveness to infect, 5 their survivability on the surface of different types of materials, 6 and contrasting among the routes of transmission remain a big challenge; therefore, these factors limit our ability to evaluate the risk.…”

Section: Introductionmentioning

confidence: 99%

Transmission of airborne virus through sneezed and coughed droplets

et al. 2020

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The spread of COVID19 through droplets ejected by infected individuals during sneezing and coughing has been considered a matter of key concern. Therefore, a quantitative understanding of the propagation of droplets containing the virus assumes immense importance. Here, we investigate the evolution of droplets in space and time under varying external conditions of temperature, humidity, and wind flow by using laws of statistical and fluid mechanics. The effects of drag, diffusion, and gravity on droplets of different sizes and ejection velocities have been considered during their motion in air. In still air, we found that bigger droplets traverse a larger distance, but smaller droplets remain suspended in air for a longer time. Therefore, in still air, the horizontal distance that a healthy individual should maintain from an infected one is based on the bigger droplets, but the time interval to be maintained is based on the smaller droplets. We show that in places with wind flow, the lighter droplets travel a larger distance and remain suspended in air for a longer time. Therefore, we conclude that both temporal and geometric distance that a healthy individual should maintain from an infected one is based on the smaller droplets under flowing air, which makes the use of a mask mandatory to prevent the virus. Maintenance of only stationary separation between healthy and infected individuals is not substantiated. The quantitative results obtained here will be useful to devise strategies for preventing the spread of other types of droplets containing microorganisms.

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Measurement of Sanitary Ventilation

Cited by 31 publications

References 2 publications

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Evaluation of a Methodology for Quantifying the Effect of Room Air Ultraviolet Germicidal Irradiation on Airborne Bacteria

Particle Image Velocimetry of Human Cough

Transmission of airborne virus through sneezed and coughed droplets

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