1 Introduction

‘Transport 2010: The Ten Year Plan’ (DETR, 2000a) sets out the Government’s strategy to tackle congestion and pollution and deliver better integrated, high quality, transport systems over the next decade. A background paper ‘Transport 2010: The Background Analysis’ (DETR, 2000b) (‘Background Paper’) has also been published which provides an overview of the modelling and analytical work that has informed the Plan. The Background Paper includes forecasts of emissions of oxides of nitrogen and particles from road and rail transport in England in 2000 and in 2010 under a number of different scenarios. It also includes an assessment of the impact of the measures in the Plan on ambient NO2 and PM10 concentrations based on the methods described in the Air Quality Strategy for England, Scotland, Wales and Northern Ireland (DETR et al, 2000) (AQS) and supporting technical reports (Stedman et al, 1998a, Stedman et al, 1998b). These methods have been updated to incorporate more recent ambient air monitoring results, understanding of atmospheric chemistry and emissions estimates and projections. This report describes these methods and presents the results of the site specific analyses of NO2 and PM10 concentrations.

NO2 and PM10 are two important pollutants addressed in the AQS. They are pollutants for which the objectives set out within the Strategy and in recent EC Directives are likely to be the most challenging. The AQS sets the following provisional objectives for NO2, to be achieved by 31 December 2005:

The first EU air quality ‘daughter directive’ (AQDD) sets the same concentrations as limit values, to be achieved by 1 January 2010. The annual mean objective and limit value is expected to be the more stringent of the two.

The AQS sets the following objectives for PM10, to be achieved by 1 January 2005:

  • Annual mean: 40 mgm-3
  • 24-hour mean: 50 mgm-3, not to be exceeded more than 35 times a year.

The AQS adopted the AQDD stage 1 limit values for PM10 as national objectives. The 24-hour mean objective and limit value is expected to be the more stringent of the two. Indicative stage 2 limit values have also been set at 20 mgm-3 as an annual mean and 50 mgm-3 as a 24-hour mean, not to be exceeded more than 7 times a year, to be achieved by 1 January 2010. Our analysis of the impacts of the Plan on PM10 concentrations has focussed on the achievement of the indicative annual mean Stage 2 limit value in 2010 - the timeframe of the Plan

The Government is currently considering the possibility of a more stringent AQS objective for PM10. The 10 Year Plan provides an important input to this analysis as it will provide a basis on which the impact of possible additional measures on ambient concentrations can be assessed.

The emissions projections derived for the scenarios described in the Background Paper are set out in section 2. Sections 3 and 4 describe the methods that have been used to derive estimates of NO2 and PM10 concentration in 2010 from a combination of ambient monitoring data and emissions information. Site specific projections have been calculated for both pollutants. This method has the advantage of not incorporating the additional uncertainty that would be introduced by the use of a dispersion model or mapping method. The site specific projection method involves separating the measured concentration into a number of component parts, projecting each of these parts forwards and recombining to derive an estimate of the concentration in 2010. The results of the analysis for the Plan are listed in sections 5 and 6 and discussed in section 7.

Summary           Chapter 2

Report and site prepared by the National Environmental Technology Centre, part of AEA Technology, on behalf of the UK Department of the Environment, Transport and the Regions