A new study has found that a significant proportion of ships are breaching air pollution limits.
Although the International Maritime Organization (IMO) has set regulations for shipping pollution since 2005, it is hard to know what happens once ships are at sea.
In response to this challenge, Prof James Lee from the University of York began measuring air pollution from individual ships. He said: “We wanted to see how widely the new regulations were being adhered to and then look at the effect on the atmosphere. We flew the FAAM aircraft out from the UK and Portugal to investigate in 2019 and then again in 2021 and 2022.”
The UK’s FAAM aircraft started life as a prototype short-haul airliner for about 100 passengers. Nowadays it carries up to 18 researchers and four tonnes of science equipment.
Dr Dominika Pasternak, one of the researchers on the study, said: “The most difficult part was finding the plume. We would position the FAAM aircraft in the area of operation. A person back at the airport used a ship tracker website and relayed coordinates, heading and visual description over Satcom.
“We often flew just 30 metres over water. With data on wind speed and direction, the speed and heading of the ship, some trigonometry and very skilled flying, we were able to intercept 130 ship plumes.”
In the open ocean, eight ships out of 19 were emitting more sulphur than permitted in 2019. These included a 61,900 tonne container ship and an 86,100 tonne crude oil tanker. Five ships out of 78 exceeded the stricter limits in 2021 and 2022.
A tighter air pollution zone operates in the Channel and North Sea. This was largely effective but here two out of 33 ships breached limits. In one case, a 200,000 tonne container ship was found breaching sulphur limits in the open ocean but had later switched to cleaner fuel when it was sampled nearer land in the Channel and North Sea zone.
Air pollution from burning shipping fuels can be measured further inland – in London for example – and was estimated to have cost the UK £1.5bn in health impacts in 2017.
Lee offered a message to policymakers: “The reduction in sulphur shows that regulations can have an effect. Our work also showed that ships are a significant source of local air pollution when they are sailing close to shore.
“As the road vehicle fleet becomes cleaner, shipping and aviation are likely to become the main source. Consideration should be given to any policy to reduce these.”
The IMO is expected to adopt a new emissions control area for shipping around the western UK and the north-east Atlantic, which will come into force from 2027.
