| Topic: | Re:Re:Re:Re:Re:Air pollution in Putney | |
| Posted by: | Tim Henderson | |
| Date/Time: | 16/08/13 08:14:00 |
| "there is evidence the new buses are not as clean as they were made out to be." Indeed,David Carslaw's summary of the big remote sensing study done at four sites in the City of London and Ealing in summer 2012 http://www.londonair.org.uk/london/asp/LAQNSeminar/pdf/June2013/David_Carslaw_New_findings_from_vehicle_emission_remote.pdf includes slide 24 : "Emissions from TfL buses By manufacturer and type for NOx Little evidence that more modern buses reduce NOx In particular, SCR (a system designed to reduce NOx) is ineffective Reasonably consistent emissions across manufacturers, but some variation" However, it appears that at this time the selective catalyst reduction system (SCR) used on the buses was standard equipment from the original manufacturer and was not adjusted for the slow-speed stop/start nature of most bus journeys. It is claimed that TfL are now using optimised SCR techniques which are much better - but I have yet to see data substantiating this. More remote-sensing work was done in Putney High Street earlier this year (?analysis in progress now / ?due to be reported in September) and the King's College team reported in early July : http://www.londonair.org.uk/london/asp/news.asp?NewsId=Emissionremote&StartIndex=1 "After Oxford the team will move on to London where the focus will be the quantification of NOx, NO2 and ammonia from TfL’s new bus retrofits which use an optimised Selective Catalytic Reduction (SCR) system to reduce NOx." Keeping the fingers crossed for good news. It isn't clear at the moment what penetration the optimised buses have got in the total fleet servicing Putney to judge whether they have had an impact on the July figure recorded in the local press. |