For obvious (political) reasons, very little is being said about the disproportionate contribution Hong Kong's harbour makes toward pollution. It's so much easier to zero into cars, trucks and planes, plus the "filthy" industries just across the border.
Yet here you have a massive traffic in ships burning what is essentially refinery waste - even whilst docked (just to generate a few kWs). Sulphur, fine dust particals, soot....... nobody cares. As long as we can make hou doh chinnah.