Smoke-spewing ferries spew more sulfur pollution than cars in several EU capitals, according to one analysis.
Dublin, Helsinki, Stockholm and Tallinn are among 13 of Europe’s 15 largest port cities choked more by sulfur oxides (SOx) from ferries than by road vehicles, data shared exclusively with The Guardian shows.
Europe’s aging fleet of nearly 2,000 ferries is a major but overlooked source of bad air in coastal cities.
Emissions of sulfur oxides (toxic gases that smell like burnt matches and rotten eggs) react to form small particles that enter the lungs, travel through the bloodstream, and damage organs throughout the body.
Analysis by Transport & Environment (T&E), a group that advocates for clean transportation, also found that ferries pollute more than cars in Athens and Rome, which did not feature in the ranking because their ports are considered separate cities, and in Valletta, Malta’s small capital.
The top non-capital cities on the list include Barcelona, Marseille, Rotterdam and Valencia.
“Ferris should connect communities, not pollute them,” said Felix Klann, shipping policy analyst at T&E and lead author of the report.
According to the report, ferries in Europe spend most of their time within five nautical miles of densely populated ports and, unlike larger vessels that cross oceans, many could be powered by electricity rather than dirty fuels or expensive synthetic alternatives.
The analysis found that it would have been “technically feasible and profitable” to electrify 20% of Europe’s ferries in 2025, a proportion that rises to 43% by 2030 as battery technology improves and prices fall.
“Too many ferries burn polluting fossil fuels, pumping toxic air into Europe’s port cities,” Klann said. “Electrifying them could dramatically reduce emissions and bring a breath of fresh air to millions of people.”
Analysts modeled air pollution at Europe’s 100 busiest ferry ports using methods from an International Maritime Organization (IMO) study and compared SOx emissions with those from cars based on vehicle registration data within city limits.
They represented emissions controls in three regions (the North Sea, the Baltic Sea and, from 2025, the Mediterranean) that limit sulfur content in ships to 0.1% of fuel mass. The limit is five times lower than what the IMO requires.
Together, the restrictions have contributed to a 70% drop in sulfur emissions since 2014, according to the European Environment Agency.
The report found that requirements for charging infrastructure were the main obstacle to adoption, but that most ports would only require small chargers of less than 5 MW.
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 port infrastructure to support electrification.”
Dublin Port did not respond to a request for comment. Ingrid Hansson, spokesperson for the Ports of Stockholm, said most of its customers operate “well below” the required sulfur content thresholds.
“We have been working with terrestrial energy supply since the 1980s,” he said.
“Today, a large proportion of scheduled ferry services calling at Stockholm ports are connected to shore power while docked, significantly reducing emissions of carbon dioxide, sulfur oxides and nitrogen oxides in the port area.”
Ellen Kaasik, environmental manager of the Port of Tallinn, said it has already invested in shore power supplies at five docks and installed automatic mooring systems at three boat docks in the Old City Port.
“Together with our shipping partners, we are currently evaluating other solutions, including charging infrastructure, to introduce electric or hybrid ferries on the Tallinn-Helsinki route,” he said.
The 88-kilometer (55-mile) route between the capitals of Estonia and Finland is one of the busiest in the world. The first vessel converted to hybrid technology is expected to begin operations in early 2026, while a fully electrified vessel is being planned.
“Due to the short sailing distance between Helsinki and Tallinn, the route is very suitable for electrified vessels,” said Andreas Slotte, head of sustainability at the Port of Helsinki.
He added that ports needed strong customer commitments and early cooperation before they could undertake such large investments.
“Charging infrastructure cannot be planned and built in a vacuum,” he said. “Without input from the shipping company on the real demands of its hypothetical new building, a port can’t do much.”
