Tube dust - TUC's precautionary standard

MQT on 2017-02-20
Session date: 
February 20, 2017
Question By: 
Caroline Russell
City Hall Greens
Asked Of: 
The Mayor


When last measured, which places in the London Underground exceeded the Trades Union Congress' (TUC) precautionary standard of 2.5 milligrams per cubic metre (mg/m³) for inhalable dust (as opposed to the current 10 mg/m³ Health and Safety Executive (HSE) standard) and 1 mg/m³ for respirable dust (as opposed to the current 4 mg/m³ HSE standard)? 


Answer for Tube dust - TUC's precautionary standard

Answer for Tube dust - TUC's precautionary standard

Answered By: 
The Mayor

TfL does not routinely monitor inhalable dust, as the dusts found in the Underground network tend to fall within the respirable dust range with a diameter of around 10 µm.

Respirable dust constitutes a significant proportion of inhalable dust, as the two types overlap and, therefore, monitoring respirable dust gives a good indication of the inhalable dust levels in the same atmospheric samples.

Both the HSE and the British Occupational Hygiene Society publish guidance on reducing atmospheric dusts and these are used as part of operational procedures for maintenance and construction work. Where maintenance or construction work which is likely to generate inhalable dusts is carried out, TfL ensures that suitable measures are put in place, such as personal protective equipment and local exhaust ventilation.

TfL works to the Workplace Exposure Limits from the HSE as these are the national occupational exposure standards. TfL strives to reduce exposures to as low as reasonably practical, and ensure that they do not exceed the HSE's time-weighted average over an eight hour period. 

In TfL's most recent Tube dust survey, carried out in 2016, there were nine samples (from a total of 110 samples) where respirable dust exceeded 1mg/m3. These nine samples were collected at Baker Street, Piccadilly Circus, Tottenham Court Road and Waterloo stations. The highest reading collected was 1.30mg/m3, which remains significantly below the HSE standards.