Bert Blocken of Eindhoven University of Technology (TU / e) and Catholic University (KU) Leuven told Belgian media that computer simulations show that breath, cough and sneeze droplets can still hang in the air after a cyclist or jogger has passed. It is unclear what this means for the spread of the coronavirus.

On Thursday, Blocken told the Flemish newspaper Het Laatste Nieuws that, according to computer simulations, a hiker's breath, cough and sneeze droplets may still be present in the air 4 to 5 meters behind the hiker and that cyclist's breath, cough and sneeze droplets may even be present up to can still be in the air 20 meters behind the cyclist.

The drops are in the so-called 'slipstream' of the athlete, the zone that arises immediately behind someone when he or she moves quickly. If someone is behind this athlete, they can come into contact with those breath, cough or sneeze droplets, according to Blocken.

Blocken has not yet published his research and the results have therefore not yet been checked by scientists who were not involved in the research.

Outdoor contamination hazard unclear

Cough and sneeze droplets are thought to be the primary way people get infected with the coronavirus. However, it is still unclear how easily the coronavirus spreads in the open air and we therefore do not know the role of outdoor sports. For example, Blocken himself writes that it is still a subject of debate whether cough and sneeze droplets still pose a risk of infection after they have got on your clothes or body and have evaporated.

Blocking certainly does not want to discourage people from exercising. He advises people to exercise side by side or diagonally behind each other, in order to stay out of the slipstream. "People have to be a little more careful than the government now recommends," says the professor.

RIVM advises to keep at least 1.5 meters away from others.

Improvement: It was previously not stated that the study has not yet been published and it is unclear how the coronavirus spreads in the open air. That's added in this version.

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The coronavirus in short

  • The coronavirus mainly spreads through sneezes and cough drops. Most patients have mild (flu-like) complaints. These are the symptoms.
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