Experts warn Tube trains with open windows are exposing Londoners to filthy air

District line commuters faced unusually high levels of toxic air
PA

Tube trains running underground with open windows are exposing commuters to a “very high concentration” of filthy air, scientists warned today.

The academics from Surrey University compared journeys on the District line with those on the deep Northern and Victoria lines.

Carriages on the District line with windows left open were found to have more than double the small particulate matter (PM2.5) pollution level than those with non-openable windows.

Trains in underground tunnels on the Northern line had more than 12 times the PM2.5 pollution than for carriages on sections overground.

Research into Tube air toxicity is still at an early stage, with one 2005 report finding it was unlikely to represent a significant risk. But the Surrey study concluded: “Substantially higher concentrations of all pollutants, especially PM, were observed in underground carriages with openable windows and in the underground sections.”

London Pollution - In pictures

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Particulate pollution on both the Victoria and Northern lines, where windows were normally open, was found to be more than three times higher than on the District, with “extreme peaks” on trains when they were in the underground tunnels. New carriages being introduced by Transport for London on the deep lines have sealed windows.

Dr Olivia Carlton, TfL’s head of occupational health, said: “Levels of dust on the Tube ... remain well below the limit set by the Health and Safety Executive. We always consider the results of research in this area and will review this study.”

People walking to Tube stations were exposed to “much higher” particulate pollution than on the streets as soon as they entered the building. Underground platforms had significantly raised pollution levels compared with those above ground. Tube pollution is largely believed to be due to brake and rail friction and dust, but the study found sulphur readings suggesting that traffic pollution is seeping into the network.

The research also compared commuting by Tube, bus and car into the City from four locations, Haringey, Newham, Barnet and Wandsworth, including walking to and from stations and bus stops.

Field workers, monitored by GPS, made 232 journeys between February 25 and June 17 last year. Although particulate pollution was highest on the Tube, levels of ultrafine fine particles, linked to combustion sources and believed to be more harmful, were significantly higher on buses, and cars.

Dr Prashant Kumar, one of the papers’ authors, said: “We found that there is definitely an element of environmental injustice among those commuting in London, with those who create the most pollution having the least exposure to it.”

People on lower incomes tend to use buses rather than drive.

The journeys explored also found that by bus they took between 67 to 108 minutes, car 50 to 66 minutes, and Tube 43 to 56 minutes.

Buses also have higher particulate pollution than cars, according to the study published in Environment International, and drivers cause the most pollution per commuter.

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