Request ID: FOI-1861-2324 Date published: 18 September 2023
You asked
Hello, I would like to know the amount PM particle pollution on the London Underground. As well as dust, large amounts of PM particles including Iron Oxide will be produced and these will be present on the platforms and inside the train carriages. I expect TfL would have conducted studies and research to monitor and measure this.
Please advise the PM 1.0 and PM2.5 concentration in micrograms per cubic metre measured between April 2019 and March 2023.
We answered
Our ref: FOI-1861-2324/GH Thank you for your request received by Transport for London (TfL) on 29 August 2023 asking for information about PM particle pollution on London Underground. Your request has been considered under the requirements of the Environmental Information Regulations and our information access policy. I can confirm that we do hold the information you require. Tube dust is a mix of metal particles, organic matter and mineral dusts. From analysis undertaken by King’s College the largest proportion is iron oxide, caused by track and wheel wear and braking. It also includes organic materials from people e.g., skin and hair, elemental carbon, some minerals and metal oxides. We undertake annual dust monitoring at 24 locations, details of the locations and results are published on the TfL website. The results go back to December 2018. https://tfl.gov.uk/corporate/publications-and-reports/environment-reports December 2018 - https://content.tfl.gov.uk/simulated-passenger-journeys-2019.pdf April 2019 - https://content.tfl.gov.uk/dust-monitoring-april-2019.pdf February 2020 - https://content.tfl.gov.uk/dust-monitoring-february-2020.pdf October 2021 - https://content.tfl.gov.uk/train-operator-dust-monitoring.pdf https://content.tfl.gov.uk/dust-monitoring-lu-stations.pdf A further report - including station and on-train monitoring from 2023 - will be available on the website later in 2023. TfL apply respirable dust limits for PM4.3 which are set by the Health and Safety Executive. The UK legal ambient limits for PM2.5, or the WHO recommended limits, are not appropriate for enclosed environments such as the London Underground network. This is because these limits for ambient air quality only apply to outdoor areas and are representative of typical population exposure to outdoor air quality concerns such as traffic exhaust fumes. The health evidence beyond ambient air quality limits is based on studies in these environments. Hence there is currently insufficient health evidence to suggest the UK ambient air or WHO limits are appropriate on the Tube network, given that composition of material is different, and customers are only exposed to the dust for relatively short periods of time during their journeys, or for a few hours at time in relation to staff working patterns. the Government’s Committee on the Medical Effects of Air Pollutants (COMEAP) reviewed the evidence on the health effects of particulate matter in the Tube at TfL’s request. COMEAP advised in 2018 that there is currently insufficient evidence to determine the health impact of underground particulate matter and that further research is needed. We have commissioned academic studies to better understand the potential health impacts of Tube dust. While these are undertaken, our monitoring focuses on ensuring we comply with the HSE and IOM legal requirements (based on 8-hour average dust levels). If this is not the information you are looking for, or if you are unable to access it for some reason, please do not hesitate to contact me. If you are not satisfied with this response please see the attached information sheet for details of your right to appeal. Yours sincerely Graham Hurt FOI Case Officer FOI Case Management Team General Counsel Transport for London
