Air quality on London Underground ’30 times worse than congested roads above’

The Committee on the Medical Effects of Air Pollutants (COMEAP) warned Transport for London it was “likely that there is some health risk associated with exposure to underground PM” – tiny particles known as particulate matter.

In its first study looking into the issue since 1998, COMEAP found underground particles were larger in size and concentration than those in outdoor air above ground.

Researchers found that a person travelling on a bus for two and a half hours was exposed to a third of what they would be travelling on the Tube for just an hour.

Unpublished data from King’s College London also showed that Hampstead station on the Northern Line had the highest levels of pollution.