
 
 Summary
 The epidemics of severe acute respiratory syndrome (SARS) in 2003 highlighted both short- and long-range transmission routes, i.e. between infected patients and healthcare workers, and between distant locations. With other infections such as tuberculosis, measles and chickenpox, the concept of aerosol transmission is so well accepted that isolation of such patients is the norm. With current concerns about a possible approaching influenza pandemic, the control of transmission via infectious air has become more important. Therefore, the aim of this review is to describe the factors involved in: (1) the generation of an infectious aerosol, (2) the transmission of infectious droplets or droplet nuclei from this aerosol, and (3) the potential for inhalation of such droplets or droplet nuclei by a susceptible host. On this basis, recommendations are made to improve the control of aerosol-transmitted infections in hospitals as well as in the design and construction of future isolation facilities.
 


Iconographies supplémentaires de l'article : Factors involved in the aerosol transmission of infection and control of ventilation in healthcare premises

https://www.tandfonline.com/doi/pdf/10.1080/01441647.2020.1857886

Public transport planning adaption under the COVID-19 pandemic crisis: literature review of research needs and directions

Host-to-Host Airborne Transmission As a Multiphase Flow Problem For Science-Based Social Distance Guidelines

The ongoing Covid-19 pandemic has focused our attention on airborne droplet transmission. In this study, we simulate the dispersion of cough droplets in a tropical outdoor environment, accounting for the effects of non-volatile components on droplet evaporation. The effects of relative humidity, wind speed, and social distancing on evaporative droplet transport are investigated. Transmission risks are evaluated based on SARS-CoV-2 viral deposition on a person standing 1 m or 2 m away from the cougher. Our results show that the travel distance for a 100 µm droplet can be up to 6.6 m under a wind speed of 2 m/s. This can be further increased under dry conditions. We found that the travel distance of a small droplet is relatively insensitive to relative humidity. For a millimetric droplet, the projected distance can be more than 1 m, even in still air. Significantly greater droplets and viral deposition are found on a body 1 m away from a cougher, compared to 2 m. Despite low inhalation exposure based on a single cough, infection risks may still manifest through successive coughs or higher viral loadings.

Dispersion of evaporating cough droplets in tropical outdoor environment

Wearing face masks is recommended for the prevention of contracting or exposing others to cardiorespiratory infections, such as COVID-19. Controversy exists on whether wearing face masks during vigorous exercise affects performance. We used a randomized, counterbalanced cross-over design to evaluate the effects of wearing a surgical mask, a cloth mask, or no mask in 14 participants (7 men and 7 women; 28.2 ± 8.7 y) during a cycle ergometry test to exhaustion. Arterial oxygen saturation (pulse oximetry) and tissue oxygenation index (indicator of hemoglobin saturation/desaturation) at vastus lateralis (near-infrared spectroscopy) were assessed throughout the exercise tests. Wearing face masks had no effect on performance (time to exhaustion (mean ± SD): no mask 622 ± 141 s, surgical mask 657 ± 158 s, cloth mask 637 ± 153 s (p = 0.20); peak power: no mask 234 ± 56 W, surgical mask 241 ± 57 W, cloth mask 241 ± 51 W (p = 0.49)). When expressed relative to peak exercise performance, no differences were evident between wearing or not wearing a mask for arterial oxygen saturation, tissue oxygenation index, rating of perceived exertion, or heart rate at any time during the exercise tests. Wearing a face mask during vigorous exercise had no discernable detrimental effect on blood or muscle oxygenation, and exercise performance in young, healthy participants (ClinicalTrials.gov, NCT04557605).

https://www.mdpi.com/1660-4601/17/21/8110/pdf

Wearing of Cloth or Disposable Surgical Face Masks has no Effect on Vigorous Exercise Performance in Healthy Individuals

Rigid safe distancing rules are an oversimplification based on outdated science and experiences of past viruses, argue Nicholas R Jones and colleagues

https://www.bmj.com/content/bmj/370/bmj.m3223.full.pdf

Zeshan U Qureshi

Papers

Two metres or one: what is the evidence for physical distancing in covid-19?