Taking the Tube may be a convenient way of getting around London, but new research reveals that levels of fine particle pollution in some of the most popular Underground stations can be far higher than above ground – and in subway systems across the world.
Almost 8% of lung cancers each year in the UK are thought to be caused by exposure to PM2.5 fine particles. They’re often emitted into the air by diesel engines and other heavy machinery.
Being so small – around 1/30th of the width of a human hair – these particles can penetrate deep into the lungs. As well as lung cancer, they can cause stroke, heart disease and respiratory infections.
Researchers from Kings College London wanted to see how variations in the levels of PM2.5 particles in the Underground network compared with those above ground in traffic-congested areas like Oxford Street or open spaces such as Hyde Park.
They found that in some parts of the Tube network, concentrations of PM2.5 particles were approximately 15 times greater than on the surface in central London. This means that Underground passengers are exposed to higher concentrations of fine particle pollution than those who walk, cycle or take the bus.
Paula Chadwick, chief executive of Roy Castle Lung Cancer Foundation, was shocked by the findings.
She said, “We’ve known for some time that PM2.5 particles in the air can cause lung cancer. So, evidence about exposure to this type of air pollution when taking the Tube is particularly worrying.
“Many people still mistakenly assume that smoking is the only cause of lung cancer, but the real picture is more complex. Exposure to air pollution is also a major risk factor.
“We urge Transport for London to act on these findings and take urgent steps to protect their passengers from fine particle pollution.
“In the meantime, we’d advise anyone planning journeys in London to carefully consider their options. Walking or cycling may take a bit longer, but it will help protect your lungs, it’s good exercise, and it’s better for the environment too”.
The study also revealed that:
- PM2.5 concentrations varied between lines and locations, with the Victoria Line experiencing the highest levels and Docklands Light Railway and the District Line the lowest.
- Oxford Circus, Waterloo and London Bridge were the stations with the most exposure.
- Concentrations on the Victoria and Northern lines are greater than any reported in Beijing, Guangzhou, Los Angeles, Mexico, New York, Seoul, Taipei, Sydney and Barcelona.
On average, the London Underground handles 2.8 million passenger journeys each day and the average journey takes 47 minutes.
The study was carried out in collaboration with Transport for London (TfL) and provides information for their ongoing program of improving the air quality of the London Underground.
The King’s College research team is working with TfL to fully examine the health effects, including on London Underground workers. Using this interactive map you can learn more about the research project and how the pollution levels were calculated.