Air pollution from cruise ships could be damaging the health of people living in port cities by increasing inflammation and weakening the body’s defences against viruses such as COVID-19 and the common cold, new research has found.
Researchers, led by the University of Southampton, collected samples from five sites around Southampton’s port, including a cruise terminal, a container ship terminal and a heavy goods vehicle dock gate, with a comparison site located 5km away.
At the cruise terminal, levels of vanadium, nickel and cobalt in fine and ultrafine particles were significantly higher during the busy summer season than in quieter winter months. Concentrations increased when wind came from the direction of cruise ships and when ship presence was higher.
These metals are linked to the heavy fuel oil used to power many large ships.
To understand what this pollution might do to the body, the researchers exposed human lung cells grown in the laboratory to samples collected from different parts of the port.
The lung cells exposed to pollution from cruise ships showed the strongest signs of inflammation, reducing their ability to fight viral infections.
Professor Matthew Loxham, senior author of the study, said: ‘In this research we’ve identified a clear air pollution ‘signature’ coming from cruise ships burning fuel in ports. The ultrafine particles can penetrate deeper into the lungs than larger particulate matter and may be able to enter the bloodstream. Yet particles of this size are essentially unregulated and generally not monitored.’
Dr Nat Easton, lead author, said: ‘We see increases in concentration when the wind was coming from the direction of the cruise ships, and when cruise ship presence was higher.
‘The higher concentrations at the cruise terminal than the rest of the port is perhaps due to increased emissions from ‘hoteling’ cruise ships compared to cargo ships, but difference in fuel origins and berth occupancy times may also play a role.’
Further tests suggested that one metal in particular – vanadium – was largely responsible for these effects. The researchers believe it could play an important role in explaining why emissions from cruise ships appear to have a greater impact than other types of airborne particles.
In a laboratory, the team exposed lung cells to two different viruses: Human rhinovirus – the virus that causes the common cold and is also a major trigger for asthma attacks, and a COVID-19 model (a surrogate that behaves similarly to SARS-CoV-2 virus) to study how the virus infects cells.
When vanadium was present, both viruses replicated much more than they did without it. Instead of fighting off the virus, the cells become less able to stop it from spreading.
Professor Loxham added: ‘This has potential implications for the severity and spread of infection.’
The researchers say the findings strengthen calls for ports to adopt shoreside power from clean energy sources, carefully selected alternative fuels, or improved emissions reduction technology. They also urge better monitoring of ultrafine PM to inform regulation and protect the health of people living near ports worldwide.
The full research can be read here
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