Air-Borne Infection

Wells, W. F.; Wells, Mildred Weeks

doi:10.1001/jama.1936.02770470016004

Cited by 125 publications

(46 citation statements)

References 9 publications

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“…This is based on the assumption that SARS-CoV-2 is only transmitted as a droplet infection via the nasopharynx pathway, which mostly occurs during coughing or sneezing. These droplets do not stay in the air, but rather drop to the ground within a 1.5 m radius if larger than 5 µm [3]. It has been postulated that for SARS-CoV-2-in contrast to other respiratory-driven infections-the droplets in the aerosols are of little relevance for a COVID-19 outbreak.…”

Section: Current Decree On Wearing a Mouth And Nose Coveringmentioning

confidence: 99%

Face masks: benefits and risks during the COVID-19 crisis

et al. 2020

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Background: The German government has made it mandatory to wear respiratory masks covering mouth and nose (MNC) as an effective strategy to fight SARS-CoV-2 infections. In many countries, this directive has been extended on shopping malls or public transportation. The aim of this paper is to critically analyze the statutory regulation to wear protective masks during the COVID-19 crisis from a medical standpoint. Methods: We performed an extensive query of the most recent publications addressing the prevention of viral infections including the use of face masks in the community as a method to prevent the spread of the infection. We addressed the issues of practicability, professional use, and acceptability based on the community and the environment where the user resided. Results: Upon our critical review of the available literature, we found only weak evidence for wearing a face mask as an efficient hygienic tool to prevent the spread of a viral infection. However, the use of MNC seems to be linked to relevant protection during close contact scenarios by limiting pathogen-containing aerosol and liquid droplet dissemination. Importantly, we found evidence for significant respiratory compromise in patients with severe obstructive pulmonary disease, secondary to the development of hypercapnia. This could also happen in patients with lung infections, with or without SARS-CoV-2. Conclusion: Epidemiologists currently emphasize that wearing MNC will effectively interrupt airborne infections in the community. The government and the politicians have followed these recommendations and used them to both advise and, in some cases, mandate the general population to wear MNC in public locations. Overall, the results seem to suggest that there are some clinically relevant scenarios where the use of MNC necessitates more defined recommendations. Our critical evaluation of the literature both highlights the protective effects of certain types of face masks in defined risk groups, and emphasizes their potential risks.

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Section: Current Decree On Wearing a Mouth And Nose Coveringmentioning

confidence: 99%

Face masks: benefits and risks during the COVID-19 crisis

et al. 2020

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“…The concept of the large‐droplet sub‐route originated from Flügge, 22 who observed that respiratory activities released droplets, and that the expired organisms could not be recovered by sampling plates exposed at distances beyond 1‐2 m from the infectious person. Flügge thus concluded that the expired droplets “settled out in short distances and in brief time intervals” and that “airborne infection seemed almost eliminated” 23 . Chapin 4 then used the findings of Flügge and others to justify his theory that large droplets are the dominant route of contact transmission.…”

Section: Mechanisms Of Close Contact Transmissionmentioning

confidence: 99%

Close contact behavior in indoor environment and transmission of respiratory infection

et al. 2020

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Close contact was first identified as the primary route of transmission for most respiratory infections in the early 20th century. In this review, we synthesize the existing understanding of the mechanisms of close contact transmission. We focus on two issues: the mechanism of transmission in close contact, namely the transmission of the expired particles between two people, and the physical parameters of close contact that affect the exposure of particles from one individual to another, or how the nature of close contact plays a role in transmission. We propose the existence of three sub‐routes of transmission: short‐range airborne, large droplets, and immediate body‐surface contact. We also distinguish a “body contact,” which is defined with an interpersonal distance of zero, from a close contact. We demonstrate herein that the short‐range airborne sub‐route may be most common. The timescales over which data should be collected to assess the transmission risk during close contact events are much shorter than those required for the distant airborne or fomite routes. The current paucity of high‐resolution data over short distances and timescales makes it very difficult to assess the risk of infection in these circumstances.

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“…Since every human being carries an immense number of bacteria (Noble & Somerville, 1974), shedding from the upper respiratory tract, oral cavity, skin and hair of every person present in the operating-theatre will occur (Wells & Wells, 1936;Duguid & Wallace, 1948;Noble & Davies, 1965;Bethune et al 1965). Contamination of the air by these microorganisms is reduced by wearing a facemask, a cap and special clothing (Duguid & Wallace, 1948;Blowers & McCluskey, 1965, Bernard et al 1965Mitchell & Gamble, 1974).…”

Section: Introductionmentioning

confidence: 99%