3 minute read
physical distancing is crucial to preventing the spread of covid-19, but the two-metre distancing rules are based on outdated science, says british researchers in a paper published in the bmj this week.
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for example, researchers note that when people are vigorously exercising, heavy panting “produces violent exhalations with higher momentum than tidal breathing,” which can be similar to coughs. heavy breathing and panting will further the distance the droplets can reach. however, this is easily diluted with outdoor air. a preprint study from japan found the risk of transmission is 18.7 times higher indoors compared to outdoors.
the indoor factor is also important because not all infected people will be coughing. research has shown that the most viral load happens days before symptoms even appear.
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the highest risk situations are those indoors with poor ventilation, crowds who have prolonged contact time, and those who aren’t wearing face masks. researchers give the example of a crowded bar or nightclub. other epidemiologists have said movie theatres also pose too high a risk given theatres’ air conditioning and poor ventilation, prolonged time spent with others, and lack of ability to mandate masks in the dark.
dduong@postmedia.com | @dianaduo
