In gearing up to implement IMO 2020, the US and Canada bring years of experience enforcing an even stronger mandate.

Since 2015, the North American emissions control area (ECA) has capped the allowable sulphur content in bunkers to 0.1% for ships sailing along their coasts.

The US Coast Guard (USCG) can hold non-compliant ships within the ECA and issue civil penalties, spokeswoman Lieutenant Amy Midgett says.