Fume-belching ferries spew more sulphur pollution than cars in several EU capitals, analysis has found.
Dublin, Helsinki, Stockholm and Tallinn are among 13 of Europe’s 15 biggest port cities choked more by sulphur oxides (SOx) from ferries than road vehicles, data shared exclusively with the Guardian shows.
Europe’s ageing fleet of nearly 2,000 ferries are a large but overlooked source of foul air in coastal cities.
Emissions of sulphurous oxides – toxic gases that smell like burnt matches and rotten eggs – react to form tiny particles that penetrate the lungs, ride the bloodstream and damage organs throughout the body.
The analysis from Transport & Environment (T&E), a clean transport advocacy group, also found ferries to be a bigger polluter than cars in Athens and Rome, which did not feature in the ranking because their ports are considered separate cities, and in Valletta, the tiny capital of Malta.
Major non-capital cities on the list include Barcelona, Marseille, Rotterdam and Valencia.
“Ferries should connect communities, not pollute them,” said Felix Klann, a shipping policy analyst at T&E and lead author of the report.
Ferries in Europe spend most of their time within five nautical miles of densely populated ports, according to the report, and – unlike bigger vessels that cross oceans – many could run on electricity instead of dirty fuels or expensive synthetic alternatives.
The analysis found it would have been “technically feasible and cost-effective” to electrify 20% of Europe’s ferries in 2025, a share that rises to 43% by 2030 as battery technology improves and prices fall.
“Too many ferries are burning polluting fossil fuels, pumping toxic air into Europe’s port cities,” said Klann. “Electrifying them could dramatically cut emissions and bring a breath of fresh air to millions of people.”
The analysts modelled air pollution in Europe’s 100 busiest ferry ports using methods from an International Maritime Organisation (IMO) study and compared SOx emissions with those of cars based on vehicle registration data from within the cities’ limits.
They accounted for emission controls in three regions – the North Sea, the Baltic Sea and, as of 2025, the Mediterranean – that limit sulphur content in ships to 0.1% of fuel mass. The limit is five times lower than the IMO requires.
Together, the restrictions have contributed to a 70% drop in sulphur emissions since 2014, according to the European Environment Agency.
The report found requirements for charging infrastructure were the main barrier to adoption, but that most ports would require only small chargers below 5MW.
Sotiris Raptis, secretary-general of the European Community Shipowners’ Association, said the EU had introduced ambitious policies to support electrification – including a requirement for passenger and container ships to use electricity in ports by 2030 – but that “enormous” investments were needed to finance the energy transition in shipping.
“What we are missing is investment in clean fuels, energy and infrastructure in ports to support electrification.”
The Port of Dublin did not respond to a request for comment. Ingrid Hansson, spokesperson for the Ports of Stockholm, said the majority of their customers operate “well below” the required sulphur content thresholds.
“We have been working with onshore power supply since the 1980s,” she said.
“Today, a large proportion of regular ferry services calling at Ports of Stockholm connect to onshore power while at berth, significantly reducing emissions of carbon dioxide, sulphur oxides and nitrogen oxides in the port area.”
Ellen Kaasik, environmental manager at the Port of Tallinn, said it has already invested in onshore power supply at five quays and installed auto-mooring systems at three vessel quays in the Old City Harbour.
“Together with our shipping partners, we are currently assessing further solutions – including charging infrastructure – to introduce electric or hybrid ferries on the Tallinn-Helsinki route,” she said.
The 55-mile (88km) route between the Estonian and Finnish capitals is one of the busiest in the world. The first vessel converted to hybrid technology is expected to start operations in early 2026, while a fully electrified vessel is in planning.
“Because of the short sailing distance between Helsinki and Tallinn, the route is very well suited for electrified vessels,” said Andreas Slotte, head of sustainability at the Port of Helsinki.
He added that ports needed firm commitments from customers and earlier cooperation before they could undertake such large investments.
“Charging infrastructure cannot be planned and built in a vacuum,” he said. “Without the input from the shipping company of the actual demands of their hypothetical newbuild, there is only so much a port can do.”
