Hampstead station

TfL’s research found that particulate matter in some tube stations was up to 30 times higher with respect to roads in London. Credit: Sunil060902.

A study has found that the pollution levels on the London Underground are significantly higher compared to busy city roads, according to media sources.

Commissioned by Transport for London (TfL), the research found that particulate matter (PM) in some tube stations was up to 30 times higher than that found on roads in London.

It reported that the Northern Line of the subway system is the most polluted, with Hampstead Station on the line recording the highest concentration of PM.

Over a ten-day period, Hampstead recorded on average 492 micrograms of PM 2.5 per cubic metre (μg/m3) of air, compared to 16 on a busy road in London.

The research was carried out by the Committee on the Medical Effects of Air Pollutants.

“It is likely that there is some health risk associated with exposure to underground PM.”

In the report, the committee was quoted by media sources as saying: “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.”

London Underground is the world’s oldest subway system, with 11 lines serving 270 stations.

The report cited ‘deep, poorly ventilated tunnels’ as one of the potential causes of such severe pollution.

Transport for London asset operations director Peter McNaught was quoted by the Guardian as saying: “We are committed to maintaining the cleanest air possible for our staff and customers when using the tube.”

According to a 2015 study by researchers at King’s College London, around 9,500 people in London die every year due to air pollution, reported Reuters.