Air Quality on the Tube (1)

MQT on 2013-07-17
Session date: 
July 17, 2013
Question By: 
Stephen Knight
Liberal Democrats
Asked Of: 
The Mayor


Why did you recently state that dust levels on the tube were below 1 mg/m3 (MQ1298/2013), when in answer to MQ 0788/2013 you made clear that the most recent readings were up to 1.23 mg/m3?


Answer for Air Quality on the Tube (1)

Answer for Air Quality on the Tube (1)

Answered By: 
The Mayor

The answer to MQ0788 / 2013 contains the actual dust levels recorded during the monitoring period (typically an eight hour period). In order to compare to the HSE levels, staff exposure is calculated as a time weighted average over an eight hour working day. This means their specific exposure to dust is lower than the actual dust levels recorded because station staff are based at several locations during the course of their working day and train operators aren't typically in the cab for the entirety of their shift.

The answer provided last month said: TfL measures air quality regularly on the Tube and results show dust levels are consistently below the Workplace Exposure limits set by the Health and Safety Executive (HSE) as the enforcing body. They are also below the guidance levels recommended by the Institute of Occupational Medicine (IOM), at 1 mg/m3 and 5mg/m3 for 'respirable' and 'inhalable' dust respectively.