If any clarification of this request is required please do not hesitate to contact me using the details below, rather than waiting until the end of the 20 day timescale. If, for any reason, you are considering not providing the requested information, please provide advice and assistance as to how I may be able to access this information as per section 16(1) of the Act. I would appreciate it if you could acknowledge receipt of this email as soon as possible. Please could you provide the following information, broken down for each TFL underground station: 1. The annual and monthly average levels of PM2.5, PM4.0 and PM10 concentration measurements at platform level 2. The highest levels of PM2.5, PM4.0 and PM10 concentration measurements at platform level recorded in each month of 2019 3. If it is still the case that only PM4.0 is monitored, please provide a reason as to why PM2.5 and PM10 are not yet monitored. If not all of the above mentioned levels of particulate matter are monitored, please do not reject this request but rather provide the information for the levels which are monitored.

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TfL Ref: EIR-3425-1920

Thank you for your request of 10^th February 2020 asking for information about particulate matter in London Underground stations.

Your request has been considered in accordance with the requirements of the Environmental Information Regulations and our information access policy.

I can confirm that we hold some of the information you require. Your questions are answered in turn below:

Question 1: The annual and monthly average levels of PM2.5, PM4.0 and PM10 concentration measurements at platform level

And;

Question 2. The highest levels of PM2.5, PM4.0 and PM10 concentration measurements at platform level recorded in each month of 2019.

TfL does not have any permanent, real time monitoring equipment located on the London Underground network to continuously measure dust levels and therefore cannot answer the questions as asked. London Underground periodically monitors dust levels at a selection of stations and lines only, for occupational exposure purposes using two methodologies. These are:

• Collection of specific aerodynamic diameter fractions (mostly respirable dust – PM 4.3) of dust on filter papers over 4 hour monitoring periods to assess the exposure of London Underground staff and others. This work is undertaken by external contractors at a sample selection of stations and underground lines;

• Use of photo optical light scattering meters to read dust levels in a variation of situations. Depending on the meter used in some instances PM 2.5 and 10 fraction sizes can be measured. These are predominantly used in-house to assess exposures such as those to passengers in cabins travelling along the network.

Given this, we do not hold either annual or monthly ‘average levels’ for each station at platform level, or records of highest levels each month. Data from our selective monitoring is published on our website here, reporting on monitoring undertaken in 2016 and 2017:

http://content.tfl.gov.uk/dust-monitoring-london-underground-network.pdf

http://content.tfl.gov.uk/respirable-airborne-dust-monitoring-at-various-london-underground-stations-and-train-lines-2017.pdf

Question 3. If it is still the case that only PM4.0 is monitored, please provide a reason as to why PM2.5 and PM10 are not yet monitored.

TfL is committed to maintaining the cleanest air possible for its staff and customers when using the Tube. We closely monitors dust levels on the Tube, in both stations and tunnels. It is vital that we operate with the very latest understanding of the risks arising from particles in the air, which is why we have enhanced our sampling regime to include tests for additional metals, have commissioned new research into the effects of Tube dust, and will continue to investigate and implement innovative ways to keep dust and particles to an absolute minimum.

Most dust monitoring to date has been in PM 4.3 fraction (PM 4.0 if taken with a meter) because it is with this that London Underground can compare against Health and Safety regulatory standards. Conversion to PM 2.5 and PM 10 equivalents is a straight forward process in that PM 2.5 from the same sample air mass is approximately 5% less than PM 4. PM 10 is approximately 10% more than the PM 4.0 measurement for the same sample air mass. Moving forward, the next round of monitoring will include PM 2.5 and PM 10 measurements. This is scheduled to take place in spring and summer 2020.

All dust measurements recorded on our network meet Health and Safety Executive limits, and we are working to meet the Institute of Medicine’s much stricter target of 1mg/m3 for respirable dust, averaged over an 8-hour time weighted average reference period. As an average across the Tube network (based on the periodic monitoring that we undertake at selected stations), dust levels do not exceed this level. TfL spend around £60 million every year cleaning its trains, stations and tunnels. We have increased the number of times cleaning is done in areas where inspections show dust is accumulating. We're also trying new cleaning methods, and will incorporate the most effective ones into our cleaning regime.

Please see the attached information sheet for details of your right to appeal as well as information on copyright and what to do if you would like to re-use any of the information we have disclosed.

Yours sincerely,

David Wells

FOI Case Officer

FOI Case Management Team

General Counsel

Transport for London

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