Future Air Quality in Danish cities

1. Introduction

Background and Objectives

The EU Commission has in co-operation with the European Auto- and Oil industry carried out the Auto-Oil Programme. The aim of the programme was to identify cost effective measures to comply to future EU air quality standards in cities in 2010 according to the new EU directive "Council directive 1999/30/EC of 22 April 1999 relating to limit values for sulphur dioxide, nitrogen dioxide and oxides of nitrogen, particulate matter and lead in ambient air". Based on the study, EU directives have been proposed and partly approved to regulate vehicle emissions and fuel qualities. These directives include directive 98/69/EC on emissions from motor vehicles (EC 1998), directive 98/70/EC on the quality of petrol and diesel fuels (EC 1998a), and directive 99/96/EC relating to heavy trucks (EC 1999).

The aim of the present project is to evaluate the impact on the future air quality in selected Danish cities of the new EU directives and proposals on vehicle emissions and fuel qualities. Furthermore, the objective is to compare the estimated future air quality with air quality limit values for protection of human health approved or proposed by EU as well as air quality guidelines by WHO and the Danish EPA.

Overall Methodology

The assessment is carried out for the reference year 1995 and the scenario years: 2000, 2005, 2010, 2015 and 2020.

Modelled substances include health related substances: NO₂ (NO_x), O_3, CO and benzene. Predictions for particles are based on expert judgement.

Future air quality levels are predicted in a selected street in Copenhagen (Jagtvej) that represent a near worst case. Air quality levels in the street is modelled by nested modelling taking into account emissions in the street, urban background levels and regional background levels. Interactions between the street air, the urban background air and the regional background air together with chemical transformations are modelled.

Additionally, calculations are carried out with less detailed input data for 103 other streets in the Copenhagen area with a wide range of traffic loads and street configurations to be able to generalise and relate the results to general traffic conditions in urban areas.

Danish Eulerian Model (DEM)

Regional background levels are predicted by the Danish Eulerian Model (DEM), a large-scale transport model based on 50 x 50 km² emission grids for all Europe and meteorology on a 150 x 150 km² grid. Development in European emissions is based on proposals for the new ECE protocols on regulation of trans-boundary air pollution.

Danish Urban Background Model (UBM) and Urban Emission Model (UBE)

The urban background levels are modelled by the Danish Urban Background Model (UBM) based on a 2 x 2 km² emission grid for the urban area. Grid emissions are determined by a Urban Emission Model (UEM) that takes into account the traffic levels on the road network. The model was originally developed by the Danish Road Directorate but it has been improved as part of the present project. Development in traffic emission factors is based on the EU COPERT III emission model, proposed emission reductions and prediction of the development of the age profile of the Danish car fleet.

Danish Operational Street Pollution Model (OSPM)

Air pollution levels in the street are modelled by the Danish Operational Street Pollution Model (OSPM) as a contribution from the direct traffic emission in the street and a contribution from the urban background. Vehicle emission factors are also based on COPERT III.

Content of Report

Chapter 2 outlines the overall methodology for prediction of future air quality levels. The applied models are shortly described, and this chapter also includes a short description of the selected case areas and scenario studies.

Chapter 3 describes the assumptions for and the development in emission factors based on COPERT III.

Chapter 4 includes a validation study of the prediction of the regional background levels by the DEM model and results from scenario studies.

Chapter 5 comprises a validation study of the prediction of the urban background levels by the UBM and UEM models and results from scenario studies.

Chapter 6 includes a validation study of the prediction of the street levels by the OSPM model and results from scenario studies. The results are compared with EU air quality limit values as well as WHO air quality guidelines and the Danish EPA air quality criteria.

In chapter 7 the results of the present study is compared with the ongoing EU study "Urban Impact Assessment" of the Auto-Oil Programme in 11 European cities as well as national vehicle emission scenarios carried out by the EU Commission.

Appendices include detailed information about the assumed development in traffic and emissions used as input for the different models.

Unit Conversion

The following values are used for conversion between different units:

*As NO₂-units.
**ppm to mg/m³.
***mg/m³ to ppm