Where does air pollution come from?

My problem with pollution is that… you need to measure it, and those who pollute don’t do it consciously. Anecdotally I often drive through a small town. You can smell pollution, a plastic smell. In winter you can see column of smoke coming out of chimney. Sometimes it’s milky white, sometimes it thick black. There are many like that. I asked shop keeper is it happening often, she confirmed and said that no one is interested in doing otherwise, installing sensors was directly opposed by town council.

The town is not on a pollution map. Nearby cities are with medium-high pollution but that particular region is supposedly clean as reported by a single sensor positioned somewhere on a hill.

It’s not like there is one town like that in the world. There are nations that pollute heavily and don’t care and don’t meter the impact. I would be curious if all the effort, regulations etc. are worth it when applied to average Joe versus huge polluters.

One way to address this sort of localism (where there's a significant risk that the owners of the factory are slipping the town councillors the odd brown envelope) is a national regulator. The Irish EPA, which was created to take this sort of thing out of the hands of the local authorities, has been very effective in reducing nuisance pollution; the local authorities used to be mostly pretty useless. Any industrial facility of this sort would be required to self-monitor, and would be subject to inspection; it would have to respond to any complaints, and if the regulator wasn't satisfied it could demand improvements, on pain of withdrawing its operating license.