Basically title, i put one filter in, it starts running and removing pollution, and then i cut out power to it, so the recipe is unfinished, machine is without power, but it keep removing pollution around it. Also it seems like you cannot put multiple air purifiers in the same chunk, the amount of pollution they all remove together is the same as if i used a single one

removed

A single filter removes 200 pollution per second. I made the number so big for the time being so may be you saw no difference because your factory doesn't produce so much pollution per chunk.