Air pollution from cruise ships could be increasing the risk and severity of viral infections among people living near busy ports, according to new research from the University of Southampton published in Environment International. The study examined air quality around Southampton Port and found that emissions from cruise ships contain ultrafine particulate matter (PM) enriched with trace elements produced by burning shipping fuel. Laboratory experiments showed that these tiny particles can trigger inflammation while weakening the body’s natural defences against viruses such as the common cold and COVID-19.
Ultrafine particles are far smaller than most regulated forms of air pollution, measuring no more than one thousandth the width of a human hair. Because of their size, they can penetrate deep into the lungs and may even enter the bloodstream. The researchers identified a distinct pollution “signature” associated with cruise ship emissions, particularly high levels of the metals vanadium, nickel and cobalt. “We found that exposure of cells to these particles, and vanadium – the most enriched element in the particles – was both pro-inflammatory and facilitated the replication of viruses,” said Professor Matthew Loxham, senior author of the study. He added that ultrafine particles remain largely unregulated and are rarely monitored despite their potential health risks.
To identify the source of the pollution, the research team collected particulate matter samples from five locations around Southampton Port, including a cruise terminal, a container terminal and a dock gate used by heavy goods vehicles. A comparison site located five kilometres away provided a benchmark. Sampling took place during both the busy spring and summer cruise season and the quieter winter off-season, allowing the researchers to compare changes in pollution levels throughout the year.
The analysis showed substantially higher concentrations of vanadium, nickel and cobalt in fine and ultrafine particles at the cruise terminal during the summer, when cruise ship traffic was at its highest. These trace elements were also generally more abundant across the port than at the comparison site. Lead author Dr Nat Easton said pollution levels consistently increased when winds carried emissions from cruise ships towards the sampling locations. The researchers believe emissions from cruise ships while docked, together with differences in fuel types and time spent in port, likely contributed to the elevated concentrations.
Laboratory tests using human lung lining cells revealed that exposure to ultrafine particles collected during the busy cruise season increased the activity of genes linked to inflammation while suppressing genes involved in antiviral defence. Additional experiments focused on vanadium showed that lung cells exposed to the metal produced significantly more copies of both human rhinovirus, which causes the common cold, and the virus responsible for COVID-19. These findings suggest that vanadium reduces the ability of lung cells to limit viral replication, potentially increasing both the severity of illness and the likelihood of transmission.
The researchers say their findings strengthen the case for reducing emissions from ships operating near populated ports. They recommend greater use of shoreside electricity generated from clean energy, cleaner alternative fuels and improved emission-control technologies to reduce harmful pollution. They also call for routine monitoring of ultrafine particulate matter and further investigation into its health effects, arguing that stronger evidence could help shape future regulations aimed at protecting communities living near ports around the world.
More information: Natasha Easton et al, Ultrafine particulate matter emitted from ships drives inflammation and susceptibility to viral infection, Environment International. DOI: 10.1016/j.envint.2026.110381
Journal information: Environment International Provided by University of Southampton
