The pandemic did provide Transport for London (TfL), who manage the Underground, the opportunity to make some improvements. Ventilation systems were assessed and according to the Mayor\u2019s Transport Strategy Update in 2021<\/a> \u201cthe London Underground ventilation infrastructure is typically designed in excess of statutory minimum requirements with an adequate provision of fresh air.\u201d<\/p>\n But how fresh is the air that you\u2019re breathing on the tube?<\/p>\n \u201cThe air, even before it gets to the Underground, isn\u2019t perfectly clean,\u201d explained Dr David Green<\/a>, who leads the aerosol science team at Imperial College London and is a member of the UK\u2019s Committee on the Medical Effects of Air Pollution (COMEAP). Green is also part of a group commissioned by TfL to regularly assess the COVID-19 risk on the Underground.<\/p>\n \u201cThe urban background air already has a low level of particulate matter, but on top of that you have all these extra emissions [coming from the tube].\u201d<\/p>\n Read more about air pollution:<\/strong><\/p>\n These include particles that come from the carriage moving along the rails, the brake blocks rubbing on the wheels, and the electrical connection between the collector plate and the live rail.<\/p>\n \u201cSo you\u2019ve got iron rubbing on steel, steel on steel, iron and copper and barium from the brakers,\u201d says Green. \u201cThere\u2019s lubricant on the wheels and that contains things like carbon and molybdenum. We find these metallic compounds in the atmosphere [on the Underground].\u201d<\/p>\n There are also particles that come from tube passengers, human and otherwise. Hair and skin cells, plastic fibres from clothing, and animal particulates from the creatures that call the Underground their home all contribute to the air quality.<\/p>\n Some particles are large enough to be caught by the hairs in our nose and throat, stopping them from getting into our lungs and causing damage there. These are typically referred to as PM10<\/sub>; particulate matter that is under 10 micrometres in diameter, or roughly 0.01mm.<\/p>\n The smaller particles that are under 2.5 micrometres in diameter are referred to as PM2.5<\/sub>, and these are the ones that can penetrate deep into the lungs and may also enter the bloodstream to be transported around the body, affecting the brain, heart and other organs. These are roughly about 3 per cent of the diameter of a human hair.<\/p>\n \u201cWe do not have enough evidence to state categorically whether pollution on the tube does or doesn\u2019t harm your health, but we do know that exposure to PM2.5<\/sub> is harmful. [This is shown by] studies from all over the world looking at deaths and hospital admissions, and studies on smaller groups of people including those with existing health problems.<\/p>\n \u201cHowever, the dust in subway systems is quite different from PM2.5<\/sub> in outdoor air and we do not know whether we can extrapolate these findings to the subway environment. So, we are now studying groups of vulnerable people and TfL staff to understand whether exposure to this type of PM2.5<\/sub> is harmful.\u201d<\/p>\n On top of these small particulates, there are also gaseous pollutants in the air, including ozone, O3<\/sub>, and nitrogen dioxide, NO2<\/sub>. All are monitored by the UK Government\u2019s Department for Environment Food & Rural Affairs, whose 2020 publication found that there has been a long-term decrease in all of the pollutants<\/a> measured.<\/p>\n However, UK values for PM2.5<\/sub> are still higher than the guidelines set by the World Health Organization<\/a>, who recently changed their target to a mean annual exposure not exceeding 5 micrograms per metre cubed (\u03bcg\/m3<\/sup>). Previously, this was 10\u03bcg\/m3<\/sup>. The European Union limit is 25\u03bcg\/m3<\/sup>, which is also the limit put in place by UK law.<\/p>\n \u201cThe new WHO guideline is very challenging and currently I don\u2019t think any location in the UK will meet this,\u201d says Green. One study by the UK government from 2020 found that four out of the top five urban environments with the greatest annual PM2.5<\/sub> values were located in the London, South East or East of England<\/a> regions. According to the latest COMEAP study, concentrations of PM2.5<\/sub>\u00a0on the London Underground were many times greater than in other London transport environments, and greater than on other subway systems around the world.<\/p>\n However, when thinking about the air quality in the Underground, Green says it\u2019s important to consider the context within the range of transport modes. A report in 2021 compared the PM2.5<\/sub> averages across the tube, bus, car, three types of trains, cycling and walking.<\/p>\n Interestingly, the lowest exposures were found on electric and hybrid-style trains, even compared to cycling and walking \u00ad\u2013 though this was not the case when these trains were in stations alongside diesel-powered trains.<\/p>\n \u201c[Travelling on the tube] for one hour every weekday for 48 weeks a year (assuming 4 weeks holiday) on the Victoria line would increase your annual exposure to PM2.5<\/sub> by 6.8\u03bcg\/m3<\/sup>,\u201d says Green. This increase is on top of individuals\u2019 usual exposure to pollutants in the air, which varies by location, as some of the small particles measured as PM2.5<\/sub> occur naturally, like dust and salt from the sea.<\/p>\n \u201cThis compares to 0.3\u03bcg\/m3<\/sup> at a background site in London, 2.6\u03bcg\/m3<\/sup> on an average London Underground line or 1.2\u03bcg\/m3<\/sup> in a car. But remember the car pollutes everyone else as well.\u201d<\/p>\n For Green, this is key. \u201cIt is much better that people get on the London Underground than it is for them to get in their car to move around London. That\u2019s because if you\u2019re sitting in your car, you\u2019re exposed to very high concentrations of vehicle pollutants.<\/p>\n \u201cYou\u2019re sitting directly behind the exhaust of the car [in front], so you have a higher exposure than cyclists riding along the road or the pedestrians walking past. And the other thing is you\u2019re also polluting the world for everybody else. So, while the car isn\u2019t worse than the tube in the case of PM2.5<\/sub>, it is much worse for other pollutants like nitrous oxides.\u201d<\/p>\n For those who need to travel on the tube, then, it becomes a matter of choosing the best route. Green\u2019s research found that the lines that run deeper are generally worse, like the Northern line, compared to higher level lines like the Circle, District, Hammersmith & City, and Metropolitan lines. Older lines and the type of trains used all play a part. So, Green suggests opting for newer lines and stations that have platform doors installed to reduce exposure. \u201cBut in general, there\u2019s not a great deal of choice,\u201d he admits.<\/p>\n Green is also concerned with the health of the staff on the London Underground, who spend much longer on the tube or at one station. Unfortunately, there isn\u2019t enough data to say yet what the long-term health impacts of this will be.<\/p>\n \u201cWe\u2019re working closely with Transport for London (TFL) to compare sickness absence from people working in London Underground with other TFL workers. We also want to look at pension data, to see if people who work on the tube may die a little earlier than people who don\u2019t. But [these studies] are in the early stages at the moment.\u201d<\/p>\n Tube passengers can be reassured that the risk of catching COVID-19, however, is minimal across all of the Underground.<\/p>\n \u201cTube trains and stations are cleaned with hospital-grade cleaning substances that kill viruses and bacteria on contact and provide ongoing protection,\u201d a TfL spokesperson told BBC Science Focus<\/em> magazine.<\/p>\n \u201cIndependent testing by Imperial College London has been carried out monthly since September 2020, taking swabs of touch points in stations, on buses and of air samples in ticket\u202fhalls and\u202fup to the last verified testing round in December 2021 has found no traces\u202fof\u202fcoronavirus\u202fon the public transport network.\u201d<\/p>\n Dr David Green<\/strong> is a senior research fellow at Imperial College London, where he leads the Aerosol Science Team. His research focuses on particulate matter in the air and how this affects the health of populations.<\/p>\n Read more from\u00a0Reality Check<\/em>:<\/strong><\/p>\n <\/p><\/div> <\/section><\/body><\/html>\n By Amy Barrett Published: Monday, 07 March 2022 at 12:00 am On any given weekday, the London Underground sees up to five million passengers hopping on and off its network. Its 11 lines serve 272 stations, and at peak times there can be over 500 trains hurtling around beneath the streets of London. Despite its […]<\/p>\n","protected":false},"author":24,"featured_media":6374,"template":"","categories":[27],"acf":{"readingTimeMinutes":"7"},"uagb_featured_image_src":{"full":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health.jpg",1200,800,false],"thumbnail":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health-150x150.jpg",150,150,true],"medium":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health-300x200.jpg",300,200,true],"medium_large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health-768x512.jpg",768,512,true],"large":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health-1024x683.jpg",800,534,true],"1536x1536":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health.jpg",1200,800,false],"2048x2048":["https:\/\/c01.purpledshub.com\/uploads\/sites\/42\/2022\/03\/does-the-air-pollution-on-the-london-underground-harm-your-health.jpg",1200,800,false]},"uagb_author_info":{"display_name":"importmanagerhub@sprylab.com","author_link":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/author\/importmanagerhubsprylab-com\/"},"uagb_comment_info":0,"uagb_excerpt":"By Amy Barrett Published: Monday, 07 March 2022 at 12:00 am On any given weekday, the London Underground sees up to five million passengers hopping on and off its network. Its 11 lines serve 272 stations, and at peak times there can be over 500 trains hurtling around beneath the streets of London. Despite its…","_links":{"self":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/rss_feed\/6373"}],"collection":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/rss_feed"}],"about":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/types\/rss_feed"}],"author":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/users\/24"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/media\/6374"}],"wp:attachment":[{"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/media?parent=6373"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/c01.purpledshub.com\/bbcsciencefocus\/wp-json\/wp\/v2\/categories?post=6373"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}![\""Crowds\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/4\/2022\/02\/Crowds-of-passengers-on-Tube-platform-9947595.jpg?quality=90&resize=620%2C412"\" "\\"\"Crowds\\"")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>![\""London\"](\""https:\/\/images.immediate.co.uk\/production\/volatile\/sites\/4\/2022\/02\/London-Underground-passengers-on-escalator-c384eca.jpg?quality=90&resize=620%2C413"\" "\\"\"London\\"")
<\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/source><\/picture><\/div>About our expert<\/h4>\n
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