A comparison of projections published in the 2000 United Kingdom air quality strategy with recent measurements and modelling assessments

Air quality modelling assessments were carried out to inform the development of the UK Air Quality Strategy and in particular the setting the timescale for the achievement of objectives. These assessments were carried out in 1998 and the projections derived for 2005 and 2010 have been compared with air quality monitoring data for 2004 and 2005 and recent modelling assessments. Overall the predictions of air quality for 2005 are in reasonably good agreement with measurements and recent modelling assessments. This gives us confidence that the assessment methods used were suitable to inform the development of policy. Ambient benzene concentrations have declined more rapidly than expected and ambient NO2 concentrations have not shown as steep a decline as expected, particularly at the roadside. The most challenging objectives to achieve are those for NO2, PM10 and ozone. The challenges presented by these pollutants are because of their trans-boundary nature and the importance of chemical processes.