Underground Air Pollution

Questions to the Mayor of London – answered on 17th October 2019.

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Photo of David Kurten David Kurten Brexit Alliance

It is known that PM2.5 levels on the London Underground are many times higher than the legal limit, with Hampstead being one of the worst examples, but what are average annual concentrations of NO2, SO2, methane, ozone and volatile organic compounds at the platform level in Hampstead Station and other PM2.5 blackspots?

Photo of Sadiq Khan Sadiq Khan Mayor of London

Transport for London’s (TfL’s) cleaning regime is effective in ensuring that London Underground operates well within the Health and Safety Executive’s maximum limit for respirable dust, as is confirmed by regular monitoring.

Historically, TfL has not measured PM2.5 levels on the London Underground network. In January 2019 the Committee on the Medical Effects of Air Pollutants (COMEAP) report recommended that future monitoring includes collecting physiologically relevant fractions (e.g. PM10 and PM2.5), to enable London Underground (LU) Particulate Matter to be included in wider toxicity studies. This recommendation has been accepted and will be implemented in TfL’s next round of monitoring.

TfL does not measure these pollutants, which are not produced inside the LU network.

The dust in the London Underground comes from a range of sources. This includes the brakes being applied on trains as well as rail and wheel wear. Other compounds in the dust include textile fibres from customers, and mineral dusts

TfL spends around £60m per annum cleaning its trains, stations and tunnels to ensure dust and particles are kept to an absolute minimum. New cleaning methods are currently being trialled and the most effective will be incorporated into TfL’s cleaning regime.