Visualization: How the coronavirus spreads indoors

In this bar, capacity has been reduced to 50%. There are 15 patrons and three members of staff. The windows are closed and there is no mechanical ventilation.

In the worst-case scenario, if no measures are taken, 14 of the customers will be infected after four hours.

If masks are consistently used, the risk of infection falls to eight new cases.

If the premises are ventilated, which can be done with a good air conditioning unit, and the time spent in the bar is shortened, there is only the risk that one person will be infected.