No legislation is perfect. But the IMO's call for sulphur levels in marine fuel to be cut from 3.5% to 0.5% is fair and straight, as shipping emits enough SOx, NOx and particulate matter to kill 100,000 vulnerable people a year worldwide.

It is IMO policy to reduce emissions from ships, with a target to cut greenhouse gases (GHGs) by at least 50% by 2050.