Hudson Shipping Lines (HSL) has doubled down on its stance against using exhaust gas scrubbers to meet pending IMO 2020 regulations.

The US ship operator has joined Trident Alliance, a group of shipping companies focused on ensuring full enforcement of pending IMO 2020 rules.

Four months ago, it said publicly that it would boycott scrubber-fitted vessels on the premise that they transfer airborne ship exhaust into the ocean.