On the road pollution tests

MQT on 2015-09-16
Session date: 
September 16, 2015
Question By: 
Darren Johnson
City Hall Greens
Asked Of: 
The Mayor


Should TfL undertake an annual reality check of the emissions being produced by its own taxis and buses using portable emissions technology, such as the Nanoparticle Emission Tester?


Answer for On the road pollution tests

Answer for On the road pollution tests

Answered By: 
The Mayor

The London Buses emissions test cycle remains the best way to measure all types of exhaust emissions in real-world conditions from the different vehicle types that make up the fleet.

This product - one of a range of portable emissions measurement systems (PEMS) which companies market - can be used to check if a particular diesel particulate filter is working at a garage.

It does not measure oxides of nitrogen, however, and the results would not be representative of actual emissions on a route when the bus engine and exhaust system has warmed up to run at normal efficiency. To measure other emissions would require other types of PEMS which are quite bulky and protrude from the rear of the exhaust system making them a potential hazard to motorists behind.