Bayern introduced obligatory facemask (FFP2) end-January 2021.
The three regions around Bayern do not have any facemask-obligation.
Below are the graphs of detected COVID-cases in Bayern and the three regions around.
Can you see which one in Bayern?
Answer: Graph 1
Idea and elaboration: Jacob Gudiol (Twitter)
(I just translated it and put it here in my blog to have it more available)
