People travelling in London are exposed to more air pollution on the Underground than beside its busy roads, according to scientists.
In an interactive map, King’s College London scientists have revealed how air pollution can reach staggering levels inside some of the city’s Tube trains, which are used by around two million people every day.
Stockwell, on the Victoria line, was the most polluted station in the city, with 639 micrograms of PM2.5 particulate pollution per square metre.
This is 25 times higher than the European target limit of 25ug/m3 – exposure to high levels of PM2.5 is known to be linked to heart and lung diseases and cancer.
Six of the 10 worst offenders were all also on the Victoria Line – Vauxhall, Finsbury Park, Pimlico, Highbury & Islington and Brixton all scored particularly badly.
Meanwhile, commuters travelling on the District Line are blessed with the cleanest air, with Upminster, Turnham Green, Stamford Brook, Ravenscourt Park, Ealing Broadway, Chiswick Park and Acton Town all recording just 2ug/m3.
HOW TO USE THE INTERACTIVE MAP
The map below shows the readings the scientists collected in London Underground stations around the city.
To see a pollution reading for a station, zoom in and hover over the station’s name. In the top left corner, the name of the station will appear alongside a reading such as ‘4 ug m3’. This measurement shows how much PM2.5 particulate pollution was found at that station in micrograms per cubic metre of air. A cubic metre (three cubic feet) measures 1mx1mx1m.
The EU’s target limit for PM2.5 matter in the air is 25ug/m3. Figures for the Tube stations range from 2ug/m3 to 639ug/m3.
The map shows which stations have the highest levels of PM2.5 pollution (name highlighted in red) and which have the least (name in green). Stations in the centre of the city and along the Northern Line have some of the worst levels, while those in the east and west have cleaner air
To use the map on King’s College London’s website click here.
The King’s College researchers did their study by sending people with monitoring devices on testing visits.
They compared variations in PM2.5 levels – the smallest type of pollution – above ground and underground, as well as in different areas of the metro system.
While underground, the pollution was measured inside a train carriage and readings for stations represent pollution levels in that area on a specific train line. For this reason, some stations have significantly different readings for different lines at the same platforms – for example, the District and Piccadilly lines in Hammersmith.
Factors such as how much time the train spends underground, the ages of the tunnels and infrastructure, and how busy the carriages are were all factors in how much pollution each station had, the scientists said.
And they added that taking the tube was found to be the most polluted way of getting around the city – more so than cycling, taking the bus or driving.
PM2.5 pollution is known to damage the lungs and heart and people who breathe in large amounts are at risk of various serious and deadly health problems.
It raises the risk of heart attacks, irregular heartbeats, severe asthma, decreased lung function and more coughing and breathing problems.
Pollution has also been linked to cancers, particularly lung cancer.
Transport for London said the type of pollution underground is different to that which comes from roads, and is made up mainly of metal dust, rather than exhaust fumes.
WHICH UNDERGROUND STATIONS ARE MOST POLLUTED?
- Stockwell (Victoria line) – 639 ug/m3 of PM2.5
- Vauxhall (Victoria) – 481
- Finsbury Park (Victoria) – 468
- Pimlico (Victoria) – 460
- Highbury & Islington (Victoria) – 378
- Brixton (Victoria) – 374
- Bond Street (Central) – 367
- Kennington (Northern) – 361
- Oval (Northern) – 359
- Chancery Lane (Central) – 349
WHICH UNDERGROUND STATIONS ARE LEAST POLLUTED?
- Ladbroke Grove (Circle line) – 2 ug/m3 of PM2.5
- Latimer Road (Circle) – 2
- Shepherd’s Bush Market (Circle) – 2
- Wood Lane (Circle) – 2
- Acton Town (District) – 2
- Chiswick Park (District) – 2
- Ealing Broadway (District) – 2
- Ravenscourt Park (District) – 2
- Stamford Brook (District) – 2
- Turnham Green (District) – 2
‘Our aim in this study was to make high-quality measurements of the PM2.5 that people are exposed to in the London Underground,’ said senior researcher Dr David Green.
‘The results show that they can be some of the highest concentrations they will encounter during their day.
‘Currently, our understanding of the health effects of air pollution is based on measurements taken by fixed measurement stations above ground.
‘Clearly these don’t represent what people are exposed to as they travel on the underground and these new measurements will help us improve these assessments.’
Dr Green and his colleagues also said the concentrations of pollution on the Victoria and Northern lines were higher than have been recorded on underground trains in other countries.
Studies of Beijing, Guangzhou, Los Angeles, Mexico, New York, Seoul, Taipei, Sydney and Barcelona have all revealed lower levels of pollution than were found in London.
The figures showed that people travelling on the District, Circle and DLR lines of the Underground are exposed to the least pollution – these are known for spending more time above ground than others, and travelling through less built-up areas.
Values for many stations on those lines were around two to three micrograms per cubed metre.
Whereas the Victoria, Northern and Central lines appeared to be the most polluted.
Values for some of the stations on these deeper, more urban lines exceeded 300 micrograms and topped out at more than 600 in Stockwell.
The London Underground is used by around two million people every day and many of them may be exposed to harmful levels of air pollution on their journeys, King’s College London research shows (stock image)
Lilli Matson, Transport for London’s chief safety, health and environment officer said: ‘We welcome this research and will continue to engage with academics conducting further research to gain a better understanding of the health risks associated with air on the Tube.
‘The particulates found Underground are very different to those found on the surface, consisting predominantly of iron oxide rather than traffic pollutants.
‘Particulates found in air above ground are known to be carcinogens, whereas those on the Tube are not known to have that effect.
‘We spend around £60million every year cleaning our trains, stations and tunnel and are committed to maintaining the cleanest air possible for our staff and customers.’
The King’s researchers’ work was published in the journal Environment International.
WHAT HAVE RECENT STUDIES SHOWN POLLUTION CAN DO TO OUR HEALTH AND BODIES?
CAUSE CHILDREN TO HAVE A LOW IQ: Researchers at the University of California, San Francisco, found in May 2019 that children born to mothers who live in polluted areas have an IQ that is up to seven points lower than those living in places with cleaner air.
CAUSE CHILDREN TO HAVE POORER MEMORY: Researchers at the Barcelona Institute for Global Health found boys exposed to greater levels of PM2.5 in the womb performed worse on memory tests by the time they are 10.
DELAY THE DEVELOPMENT OF CHILDREN: Youngsters who live less than one-third of a mile away from busy roads are twice as likely to score lower on tests of communication skills in infancy, found researchers at Eunice Kennedy Shriver National Institute of Child Health in April. They were also more likely to have poorer hand-eye coordination.
MAKE CHILDREN MORE ANXIOUS: University of Cincinnati scientists claimed pollution may alter the structure of children’s brains to make them more anxious. Their study of 14 youngsters found rates of anxiety was higher among those exposed to greater levels of pollution.
CUT YOUR CHILD’S LIFE SHORT: Children born today will lose nearly two years of their lives because of air pollution, according to a report by the US-based Health Effects Institute and the University of British Columbia in April 2019. UNICEF called for action on the back of the study.
RAISE A CHILD’S RISK OF AUTISM: Researchers at Monash University in Australia discovered youngsters living in highly polluted parts of Shanghai have a 86 per cent greater chance of developing ASD. Lead author Dr Yuming Guo said: ‘The developing brains of young children are more vulnerable to toxic exposures in the environment.’
CAUSE ASTHMA IN CHILDREN: Four million children around the world develop asthma each year because of road traffic pollution, a major study by academics at George Washington University estimated. Experts are divided as to what causes asthma – but exposure to pollution in childhood increases the risk by damaging the lungs.
MAKE CHILDREN FAT: University of Southern California experts found last November that 10 year olds who lived in polluted areas when they were babies are, on average, 2.2lbs (1kg), heavier than those who grew up around cleaner air. Nitrogen dioxide pollution could disrupt how well children burn fat, the scientists said.
LEAVE WOMEN INFERTILE EARLIER: Scientists at the University of Modena, Italy, claimed in May 2019 that they believe pollution speeds up ageing in women, just like smoking, meaning they run out of eggs faster. This was based on them finding almost two-thirds of women who have a low ‘reserve’ of eggs regularly inhaled toxic air.
RAISE THE RISK OF A MISCARRIAGE: University of Utah scientists found in January that pregnant women are 16 per cent more likely to suffer the heartbreak of a miscarriage if they live in areas of high pollution.
RAISE THE RISK OF BREAST CANCER: Scientists at the University of Stirling found six women working at the same bridge next to a busy road in the US got breast cancer within three years of each other. There was a one in 10,000 chance the cases were a coincidence, the study said. It suggested chemicals in the traffic fumes caused the cancer by shutting down the BRCA genes, which try to stop tumours growing.
DAMAGE A MAN’S SPERM: Brazilian scientists at the University of Sao Paulo found in March that mice exposed to toxic air had lower counts and worse quality sperm compared to those who had inhaled clean air since birth.
MAKE MEN LESS LIKELY TO GET SEXUALLY AROUSED: Scientists at Guangzhou Medical University in China found rats exposed to air pollution struggled to get sexually aroused. Scientists believe it may also affect men, as inhaling poisonous particles may trigger inflammation in blood vessels and starve the genitals of oxygen – affecting men’s ability to become sexually aroused.
MAKE MEN MORE LIKELY TO HAVE ERECTILE DYSFUNCTION: Men who live on main roads are more likely to have difficulty getting an erection due to exposure to pollution, a Guangzhou University in China study suggested in February. Toxic fumes reduced blood flow to the genitals, tests on rats showed, putting them at risk of developing erectile dysfunction.
RAISE THE RISK OF PSYCHOSIS: In March, King’s College London scientists linked toxic air to intense paranoia and hearing voices in young people for the first time. They said uncovering exactly how pollution may lead to psychosis should be an ‘urgent health priority’.
MAKE YOU DEPRESSED: Massachusetts Institute of Technology researchers found in January that that the more polluted the air, the sadder we are. Their study was based on analysing social media users in China alongside the average daily PM2.5 concentration and weather data where they lived.
CAUSE DEMENTIA: Air pollution could be responsible for 60,000 cases of dementia in the UK, researchers from King’s College London and St George’s, University of London, calculated last September. Tiny pollutants breathed deep into the lungs and enter the blood stream, where they may travel into the brain and cause inflammation – a problem which may trigger dementia.