It is a Dutch-Belgian study which caused a stir on the web in recent days. According to aerodynamic physicists from the Universities of Eindhoven and Louvin, the social distancing measures recommended by governments would be insufficient for athletes and their close entourage. Sport and Covid-19 would not therefore mix so well?
En within just a few months, the Covid-19 has managed to spread to many countries around the world. Research has shown that the virus is spread by means of the micro-droplets of saliva. Airborne when a person sneezes, coughs or even expires, they are a vector of transmission. The inhalation of these droplets by another person or the deposit on the hands would therefore be vectors of pandemic spread. A person carrying the virus is considered to infect 2 to 5 other people. And what about covid-19 contamination while playing sports?
This is how the governments of countries around the world have asked their citizens to respect a distance of 1 to 2 meters between each person. Their goal is quite simply to limit the spread of the virus. If this measure is considered effective for stationary people, it would seem that the aerodynamic effects induced by moving people, increase the required distance. People moving near athletes who practice brisk walking, running or cycling would therefore be more exposed.
Wind tunnel simulations
During their research, the scientists carried out wind tunnel simulations. They thus highlighted the air flow around a runner. The analysis also helps to define the movement and evaporation of droplets emitted by a person walking or running, exhaling near another. The outside wind was considered to be absent. Different configurations of people were analyzed. Side by side, in line and staggered. The exposure of the second person to the droplets emitted by the first was then evaluated.
The results indicate that the greatest droplet exposure is obtained when the second person is aligned in the wake of the first. The exposure increases as the distance between the two runners decreases. The study concludes that while the effective social distancing measure for two immobile people is 1,5m, it is significantly increased for people on the move. In the absence of headwind, tailwind and crosswind, for a walker moving at 4 km / h, the distance would be approximately 5 meters. To walk or run safely behind a person moving at 14,4 km / h, this distance would be approximately 10 meters.
. # COVID19 #SocialDistancing when walking / running /#cycling nearby non-family members. Summary in @hbvl & @HLN_BE. Message: keep exercising but stay outside slipstreams. Movie below: for walking.
Research @TUeindhoven @LeuvenU @ansys #CFD #aerodynamics #COVID #CoronaCrisis pic.twitter.com/LFA7EkU5xG
- Bert Blocken (@realBertBlocken) April 7, 2020
Sport and Covid-19, disputed results
This study was published by the most serious academics. But it has not, however, been proven by other physicists. Specialists from other disciplines were also not consulted to adjust the parameters. The results are therefore debated within the scientific community. Jennifer kasten, assistant professor in the department of pathology at the University of Cincinnati, for example denounced the scientific publication on Facebook. She states that humans are not "spray nozzles generating a mist of droplets under constant pressure." It also indicates that the study does not take into account the notion of "viral load".
Towards a consensus?
This notion would be decisive in the spread of the virus. Bert Blocken maintains the relevance of his publication at the heart of this unprecedented "health emergency" situation. Speaking on Twitter, he recalls his precautionary measure.
“As you pass, try to step aside far enough in advance that you can follow a straight line alongside the other person. Conversely, if someone passes you, it is better to wait a certain distance before positioning yourself on the same line. "
He is also joined by other scientists, who believe that the measure is common sense. For Lim Poh Lian, consultant for the National Center for Infectious Diseases in Singapore, there is "healthy skepticism".
“For example, if a stiff breeze blows. And if you are 1 meter away. Depending on whether you are upwind or downwind of the infected person, this could decrease or increase your risk of infection. "