Project: TRAMAQ - Assessment of Primary NO2 Emissions

Reference: UG294

Last update: 04/11/2003 15:42:19


The main objective of this project is to assess the levels of NO2 actually emitted by modern engines; and to compare and reconcile the emissions with quantities from roadside sampling methods (the latter will be influenced by conversion and formation of ozone).


This was a joint project with the Highways Agency. The project has provided information on how much NO2 is actually emitted by vehicles rather than formed by the reaction of nitric oxide with ozone in the atmosphere. The objectives of the study were to:

- establish the quantity of NO2;
- determine what discrepancies exist between NO2 emitted and that measured using standard sampling measures;
- determine the sensitivity of NO2 to cold starts and transient driving cycles;
- estimate the contribution of primary NO2 emitted from vehicles to measured at road side locations.

The results were disseminated through a report (on the Department and TRL websites).

The DTI became interested in the work and requested extra testing (to be carried out at their expense).


TRL Limited
Crowthorne House, Nine Mile Ride, Wokingham, Berkshire, RG40 3GA
+44 (0)1344 773131

Contract details

Cost to the Department: £119,148.00

Actual start date: 28 June 1999

Actual completion date: 01 June 2002


Assessment of primary NO2 emissions, hydrocarbon speciation and particulate sizing on a range of road vehicles
Author: S Latham, S Kollamthodi, P G Boulter, P M Nelson and A J Hickman
July 2001
ISBN: PR/SE/353/2001
Source: TRL (not published) - available on the TRAMAQ web pages at DfT

Summary of results

  1. The key finding from the project is that the amount of nitrogen dioxide emitted directly from vehicles is greater than previously thuoght. For LDVs there was seen to be a step change in emissions between the pre-Euro 1 and Euro 1 standards but there is little change between Euro 1 and later standards. For HGVs no clear link between the vehicle standard and emissions was established.
    The research has also established a link between vehicle speed and NO2 emissions. The intricacies of this link have not been established but it is clear that a reduction in flow, for example due to a low emission zone, would cause a reduction in NO2 emissions and could be a tool to help meet national air quality objectives.