Underground travel ‘increases pollution exposure’, study suggests

Using overground transport routes, instead of London’s Underground network, could cut exposure to air pollution for commuters travelling into and out of the capital, research has suggested.

This was among the recommendations in a study carried out by King’s College London’s Environmental Research Group on behalf of the Northbank Business Improvement District, looking at the particulate air pollution exposure characteristics of workers commuting into the area on a daily basis.

Commuters may be exposed to higher levels of particulate pollution when travelling on the Underground network in London, research has suggested

Funded by the Mayor of London’s Air Quality Fund, the study followed the personal commutes of eight professionals, over two weeks, in and around Trafalgar Square, through to the Strand and the Aldwych area.

The study is thought to be one of the largest and most comprehensive assessments of the personal exposure characteristics of commuters undertaken in London.

For the first week participants took their usual route to and from work and in the second, they changed their route or mode of travel.


During both weeks they compiled data on exposure to particulate levels by wearing AethLabs microAeth AE51 portable monitoring equipment in order to compare their exposure during the different stages of the journey.

Participants used a variety of different transport methods including Underground and overground trains, cycling, driving, using the bus and walking.

In each case, the study identified that making adjustments to their journeys, either by switching transport method, or taking a route which encompassed quieter, less congested streets, led to an overall reduction in exposure to particulates of between 25% and 90%.

Eight commuters took part in the study, which monitored their journeys into and out of the Northbank BID

Perhaps most significantly the study suggested that overground trains and sections of Tube network where trains are above ground had much lower concentrations of particulate pollution than Underground sections, particularly the deeper lines.

The study noted: “The biggest contrasts in this study were between overground and Underground train journeys. Volunteers travelling in overground trains had some of the lowest particulate exposures and those on the Underground some of the highest. One volunteer in this study reduced their exposure by 89% by switching from an Underground to overground train. Overground trains are low exposure environments as they are fast and separated from the road network.”

Lead author on the study, Andrew Grieve senior air quality analyst at King’s College London, commented: “This study shows that, while it is important for the government to continue efforts to reduce pollution, there are small actions we can all take in our daily routines to reduce our exposure.”

Related Links
Personal Exposure and Air Quality in the Northbank Report


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