I would assume "crowded areas" are areas where there are more than 1 person per [pi * <social distance recommendation>^2] So as a rough example, let's say soci

I would assume "crowded areas" are areas where there are more than 1 person per [pi * <social distance recommendation>^2] So as a rough example, let's say social distancing recommendation is 6ft (this changes by jurisdiction). Then for a football field to be "crowded" you would need more than 57,600 / (pi * 36) = ~510 people evenly distributed on it. If the social distancing recommendation is 20ft, then you can only have 57,600 / (pi * 400) = 45 people on the football field before it starts getting crowded.