Think globally, suffer locally.
I like to have a look on the air pollution problem also from the global perspective. Where are the hotspots? How polluted is my city in comparison to others?
Lucky there are some online sources of measurement data like https://www.pollution.org/ or http://aqicn.org/map/world/ which seem to come from same source.
Looking on the live data you must immediately see where the problem is extreme. Some of the data were surprising for me. It came out that air pollution on the street where I am stuck in the traffic each day compares to some industrial places in China. In my case it is 'just' a local pollution, however in middle of flat towers full of people. One street away the air is more or less fine. It is the localized air pollution that causes me the headache (letter for letter) because I have to return to that location against my will every day. It is the pollution on the way to work, around the playground and the shopping center parking space we should worry about.
You can always find places in your city where the pollution is extreme and localized. It happens when an limited area is affected by an industry plant, heavy traffic or building site. In the same time few hundred meters away, on the next street is the air almost fine.
The typical example is an average traffic jam. You sit in an car which emits pollution surrounded by other cars and utility vehicles which do the same. Pedestrians walking next to a dense traffic are affected directly too. An Airport is another classical example where also air in an adjected seemingly idyllic village is affected by the permanent emissions from landing and starting planes. Ship engines are certainly not known to be environmentally friendly, therefore harbor air is seriously polluted as well.
It does little that your house is situated in a clean area, of course it helps, but you still have to travel to work and spend there 8 hours, go to a shopping center or somewhere else in the city which is in most cases polluted anyway. Everyone is exposed if you'r living in a city, if you work in the city or just stuck in regular rush hour traffic jam.