Concerns grow over poor air quality on London underground

Spending one hour on the London underground could expose you to as much air pollution as spending an entire day by a busy road, a new report suggests.

The report, commissioned by Transport for London (known as TfL) and published on Wednesday by the Committee on the Medical Effects of Air Pollutants, is the first study on air pollution on the Underground carried out since 1998.

It said the London Underground was affected more than any other subway system due to its age and the depths of its tunnels. It found that the Northern line was among the most polluted sections of the network due to its depth, with the highest concentration of PM2.5 (tiny particles linked to health problems). On some sections the air quality was five times over the level deemed unhealthy by the Air Quality Index.

Platforms at Hampstead tube station, one of the deepest stations at 60 meters below ground level, reported levels of pollution 30 times higher than the roadside.

Using data from the London Travel Demand survey, the study found that the majority of people aged between 30-59 spent roughly 60 minutes on the underground. During that time, the exposure to harmful particle PM 2.5 is the equivalent of spending 24 hours next to a busy road.

The new report said: "We cannot, rule out the possibility that there is a health risk from exposure to underground PM.

"Given that there is strong evidence that both long and short term exposure to particle pollutants in ambient air are harmful to health, it is likely that there is some health risk associated with exposure to underground PM."

However, Frank Kelly, chair of COMEAP, said: "You're down there for a short period of time – passengers should just use the tube as usual until we have better understanding of the risks."

Caroline Pidgeon, chair of the London Assembly transport committee, said more monitoring of dust and air pollution was vital: "We need to fully understand the health risk facing passengers and staff from being exposed to high levels of particulate matter."

Peter McNaught, director of asset operations at TfL, said: "It is vital that we operate with the very latest understanding of the risks arising from particles in the air, which is why we commissioned COMEAP to undertake this research. "We are committed to maintaining the cleanest air possible for our staff and customers when using the Tube."