This I did not know.
That shipping is the greatest source of air pollution in Hong Kong.
I would have thought the culprits were China factories (notoriously dirty) or cars (just as in the headline above).
The good news: straight after Hong Kong forced ships to use low sulphur fuels, air pollutants dropped 30%. So tightening up those restrictions will also have marked effects. Details in the article.
Said article being a great reference piece.
