Dust and air pollution which could pose “health risks” to passengers is higher on the Northern Line than any other part of London Underground Network.

A new report, by the Committee on the Medical Effects of Air Pollutants (COMEAP), found ‘particulate pollution’ is up to 30 times higher on the London Underground than levels beside the roads in the capital – with the highest concentrations found on the Northern Line.

Particulate pollution refers materials such as dust, dirt and smoke particles.

The chairman of the London Assembly transport committee, Caroline Pidgeon, said: “With large parts of the London Underground in deep and poorly ventilated tunnels it is vital that there is far more monitoring of dust and air pollution.

“Most importantly we need to fully understand the health risk facing passengers and staff from being exposed to high levels of particulate matter.”

The report does not definitively say there is a health risk from exposure to this type of dust and air pollution.

But it said it could not “rule out the possibility” and said it is “likely” there is some health risks associated with exposure to dust and air pollution on the Underground.

In a bid to determine whether this dust and air pollution could be harmful the report called for more monitoring of it on the London Undergrounds and said it is a “key public health challenge”.

It said “deep and poorly ventilated tunnels” could be to blame for the pollution levels.

Peter McNaught, director of asset operations 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.

“Although the report emphasises further monitoring and research is needed, it is an important contribution to the study of health effects associated with dust exposure.

“We closely monitor dust levels on the Tube and, through a wide range of measures, ensure that particle levels are well within Health & Safety Executive guidelines.”