The Airfilter description says, that it only purifies the chunk in which it was placed, but what happens if the Airfilter was placed on the border of two chunks or even between four.
See https://i.postimg.cc/Kz7Q25YJ/Factorio-Airfilter.png for an example, the yellow lines are the chunk borders, the top-left one is between two chunks and the bottom one between four. Will they choose one at random, or purify all 2/4 touched chunks?
