Where does air pollution come from?

I suspect readings are quite dependent on the specific location of the reading device. E.g. if the air quality monitor is located in a claustrophobic city street with lots of motorcycle traffic (e.g. Nha Trang), air pollution might be through the roof, but 100m away on the beach it might be clean(ish) air. Similar for 'leafy' cities (e.g. Singapore), where 100m can make a huge difference in air quality e.g. near a park vs beside a busy road.

Curious to know if the science backs up my suspicion that ostensibly 'polluted' cities sometimes have unpolluted alcoves (and 'clean' cities have spaces with bad air), so your micro environment really matters (more than the 'average' reading for that city, anyway).

but in absolute terms, pollution is so high in that street that even 1% of said beach pollution (which is already 1% of street) is already out of bounds of limits considered safe. Blue "haze" is pollution, not fog (water vapor).

Look, people do not understand scale, one motorcycle/lawnmower can have emissions of 300 cars equipped with catalytic converter. So in your street, there is 100 motorcycles which produce as much pollution as 30 000 cars in new york. this is not hyperbole to make a point. These ratios are physical reality.

electric cars have no emissions (except dust from tires which is same as fossil car). so why even use fossil transport is beyond me. also you can charge motorcycle from solar panel on your roof.

buses, vans, boats can have solar panels on their own roof to expand range of said vehicle. in malay or indonesia there is sun shining almost same throughout year. in europe /usa we have huge difference between summer and winter insolation and sun angle.