Evaluation of dust suppressants programme

MQT on 2013-03-20
Session date: 
March 20, 2013
Question By: 
Stephen Knight
Liberal Democrats
Asked Of: 
The Mayor


How do you respond to King's College London's recent evaluation of TfL's Cleaning and Dust Suppressants (CADS) programme, which found that the application of dust suppressant had 'no identifiable effect' on ambient PM10 concentrations in more typical roadside locations across London? Do you now regret describing this technology as a "wonderful contraption that tackles air quality head on" which would have an "immediate impact on air quality"?


Answer for Evaluation of dust suppressants programme

Answer for Evaluation of dust suppressants programme

Answered By: 
The Mayor

The evaluation by King's College London showed that dust suppressants can be very effective in reducing local PM10 concentrations at some locations in London, in line with my comments quoted.

The extensive and valuable TfL trial of the effectiveness of dust suppressants took place over a two year period and assessed the impact of dust suppressant application in nine locations - on five highway corridors and at four industrial waste sites. The full results of this trial and the other innovative Clean Air Fund measures delivered are available on the TfL website at: http://www.tfl.gov.uk/corporate/projectsandschemes/21103.aspx.

This trial highlighted that dust suppressants are most effective in locations with unusually high local levels of PM10 most likely due to re-suspension. For example, at industrial waste sites their use reduced local PM10 concentrations by up to 59 per cent. Some evidence of a positive effect was found at the A3211 Upper Thames Street study site, where the estimated impact was an average reduction in total PM10 concentration of approximately 16 per cent. There were unclear results or no significant effect was identified at the four other roadside locations where application took place. I will support the roll out of dust suppressants where it is most likely to be effective i.e. at industrial and major construction and demolition sites across London.