Hello,
My first post. A local school in Thailand (BanChang, Rayong) is continuously publishing high levels of PM2.5, and I used Windy to check where it might be coming from, as the school is in the country, 10km from the nearest town.
It seems that Bangkok is responsible, which is around 100km away and when the wind blows from Bangkok, it is clear what the effect is.

Now to the point... the school is also close to the sea, and whenever the wind blows from the sea it is expected that the air is cleaner. Not always.
It seems that according to the Windy forecast, the PM 2.5 is prevalent in the gulf of Thailand, and is partially fed by Cambodia.

So I checked Cambodia sources, and I see a very bad area consistently and cyclically every day.
It looks like a non industrial area. My question is why?