Some come with 10-storey slides, running tracks and private gyms while one boasts as many trees as a small city suburb. But the luxury ocean liners luring record numbers of tourists on to round-the-world cruises may not be as healthy as they seem.
Even on the open water, the air pollution on some ships is double that of central London, according to an investigation by Dispatches, the investigative series on the UK’s Channel 4.
The exhaust fumes the boats belch out at sea are not covered by regulations that limit emissions on land, and the heavy fuel oil that powers the ships’ engines is allowed to contain 3,500 times more sulphur than road fuel.
Standing on the deck, downwind of a ship’s funnel, investigators found air pollution of 84,000 ultrafine particles per cubic centimetre. This is more than double the 38,400 ultrafine particles per cubic centimetre found at Piccadilly Circus and almost 20 times as much as the 4,285 particles at Camber Sands beach on the south coast of England.
Ultrafine particles are particularly damaging to human health because they are small enough to cross the membranes in our lungs.
Matt Loxham, a respiration biologist at Southampton University, said that ultrafine particles were about a thousand times thinner than a strand of human hair. “Larger particles that we inhale usually get trapped in the airways by phlegm, or by hairs in the nostrils. But ultrafines can get right into the depths of the lung and distribute throughout the body,” he said.
“There are some areas of the ship deck that are affected by really quite high levels of particulate matter. These are levels you would expect in some of the most polluted cities in the world.”
About 1.9 million people in the UK go on a cruise each year, a 60 per cent increase since 2007. At sea, ships are free to dump raw sewage 12 miles offshore. The liners, which can carry more than 7,000 passengers and crew, are also largely unfettered when it comes to flushing out “grey water” from sinks and showers. “Although there are local regulations, there are no global regulations despite the fact the water can contain pollutants such as cooking oil, detergents, soaps and food waste,” Dispatchessaid. “Grey water is believed to have similar environmental impacts to sewage. It would be illegal to dump it in rivers on land, but not at sea.”
Dr Loxham said the air pollution could affect asthmatics and exacerbate cardiovascular symptoms for passengers with pre-existing conditions.
Daniel Rieger, of the German eco-charity Nabu, said a single cruise liner could create as much particulate matter as one million cars. “You can say that 30 cruise ships pollute as much as all the cars in the United Kingdom,” he said.
A team from Dispatches travelled on the P&O ship Oceana, which is more than 250m long, 15 storeys high and can carry more than 2,000 passengers. They used an infra-red camera to film gases that are not visible to the naked eye, and a P-Trak ultrafine particle counter to measure air pollution.
Carnival Corporation, which owns P&O, said that cruise liners made up less than 1 per cent of the world’s “50,000 commercial maritime vessels”.
“Although a tiny fraction of the global maritime industry, cruise lines are leaders in implementing alternative fuels and emission-reduction technology,” a spokesman said. “The industry has invested more than $US10 billion ($13bn) in new ships that can use alternative fuels such as liquefied natural gas.”
The company said it had spent $US400 million installing exhaust gas cleaning systems on 60 ships that could reduce particulate matter by up to 80 per cent. According to Carnival’s figures for 2015, its fleet released the equivalent of 10 million tonnes of CO2 into the atmosphere.