For the record, it is mentioned here that 'dust' naturally gives dust in the lungs, 'dust lungs' is not good either, but that is different from what I understand air pollution to be.
This has been on my mind for a long time, because after moving from Phuket to the Thayang area of Phetchaburi province, I have been wondering for a long time 'what air pollution', as there is no polluting industry at all in my area, and road traffic is also nil.
But when I look around, the air is indeed cloudy, and now I realise it is dust.