This chart explains why reopening the economy is still so risky

So, for example, with the current scenario of 400,000 cases, a restaurant or bar with more than 100 patrons would have more than a 11 percent chance of having one positive individual present at a given time. But if there are actually 2 million cases, the chances are 46 percent. And the virus also lives on surfaces for hours and days. So over the course of a day, viral particles of a few individuals on tables, door handles, and restroom sinks will certainly expose more people.

Here’s an instructive way to think about this. In Atlanta, the cars of MARTA, the rapid transit system, have a seating capacity of 64 and a total capacity of 96. Georgia had reported 26,000 cases as of Friday, though many experts assume the number is far higher. But assuming that is right, the chance of being on MARTA car with someone with the virus is 21 percent. Even if somehow only 10,000 people in Georgia have the virus, the chance of being exposed to someone with the virus during one single train ride is still around 9 percent. But if the real number of cases in Georgia is 50,000 or even 100,000, as some believe, the chances are 36 to 60 percent. And that doesn’t even take into account the viral particles left by the commuters who have already left the train. Nor repeated rides day after day.