Dust levels on the Victoria line are the worst on the London Underground, having more than trebled in the last year.
An independent study found that average concentrations of “respirable dust” – which can penetrate down deep into the lungs – detected in drivers’ cabs had increased from 0.13 to 0.43 mg/m3 (milligrams per cubic metre).
The highest level of 0.56 mg/m3 was recorded at Seven Sisters.
Respirable dust can be linked to fibrosis, scarring of the lung as well as cancer and other health complaints.
However, the levels found on the Tube were well below the legal maximum of 4mg/m3.
The Victoria line – which replaced the Northern line as having the worst dust levels - also had the highest rates of “inhalable” dust, which enters the nose and mouth during breathing.
The 0.7mg/m3 figure was well below the 10mg/m3 level before it would be considered hazardous to health.
The line runs entirely in deep-level tunnels between its two terminus stations, Walthamstow Central and Brixton.
It is subject to repeated passenger complaints due to its lack of ventilation and high temperatures in trains and within its stations.
Vauxhall station’s southbound Victoria line platform had the highest respirable dust concentration of all stations studied, of 1.62mg/m3.
Other stations with high dust levels were Embankment - on the southbound Northern line platform and northbound Bakerloo line platform - and Holborn’s Piccadilly line westbound platform.
The Circle/Hammersmith & City and District lines – all “subsurface” lines with much better ventilation – had the lowest average respirable dust concentrations.
The Jubilee line was found to have the highest concentrations of PM10 particulates while the Central line had the highest level of smaller PM2.5 particles.
On the Tube, particulate matter mainly originates from the train wheels grinding against the rails and during braking.
Iron oxide makes up about half of particulates.
Transport for London commissions experts to monitor in-cab levels of pollution experienced by drivers each year.
The study examined eight lines – the Victoria, Piccadilly, Central, Northern, Jubilee, Bakerloo, Circle/Hammersmith and City and District.
It found that particulate matter concentrations varied during the train driver’s journey.
The report said: “There were no exceedances to the COSHH (control of substances hazardous to health) limit for respirable and inhalable dust during the monitoring.
“The concentrations recorded were all below half the limit for dust of any composition to be considered hazardous to health.
“There were no exceedances to the HSE EH40 Workplace Exposure Limits for respirable crystalline silica.
“The mean respirable dust concentrations of the train operators recorded across all lines were similar for the data obtained in the 2023 and 2024.”
TfL spends about £2m a year removing dust and debris from the Tube.
Lilli Matson, TfL’s chief safety, health & environment officer said: “The robust research we have supported and commissioned means we now know more than ever about air quality on the Tube.
“Air pollution on the Tube is different to air pollution found above ground, and common air pollutants classified as carcinogenic to humans such as nitrogen oxide are not produced inside the Tube network.
“Our latest monitoring shows that dust levels have remained broadly stable in 2024, and have decreased since 2019. We’ll continue our work to reduce levels further.
"This result demonstrates our approach to understanding and tackling the issue of dust and air quality on the Tube network is making a difference, both for our colleagues and our customers.”
