The NAQS identified air quality standards for 8 priority pollutants based on the recommendations of the Expert Panel on Air Quality Standards (EPAQS) or WHO guidance where no EPAQS recommendation existed. EPAQS was set up by the Secretary of State for the Environment in 1991, and is a panel created to "advise, as required, on the establishment and application of air quality standards in the UK… taking account of the best available evidence of the effects of air pollution on human health…". Specific NAQS objectives set out the degree of compliance with each standard to be achieved by the year 2005. The NAQS has been subject to periodic review, with consultation documents being published in 1998 and 1999 (DETR 1998a, 1999).

The NAQS has now evolved into the Air Quality Strategy for England, Scotland, Wales and Northern Ireland (AQS for ESWNI), with the same goals. A second edition of the strategy was published in 2000 (DETR 2000), identifying further revisions and focused on the incorporation of air quality limit values in European Directives, and the impacts of devolution.

Aconsumtation document on new proposals for particles, benzene, carbon monoxide and polycyclic aromatic hydrocarbons was published in September 2001 and is available on the DEFRA website- see http://www.derfa.goc.uk/environment/index.htm.

Local authorities in the UK have a duty, under the 1995 Environment Act: Part IV, to review and assess air quality in their areas. The Air Quality Regulations 2000 define a staged process of review and assessment on the basis of guidance provided by DEFRA and the Devolved Administrations. The first stage primarily involves the collection of existing data on air quality measurements and emission sources for the 8 pollutants of interest in the AQS for ESWNI. These data are then used to define whether there is likely to be an air quality problem in a specific future year (depending on pollutant). The second and third stages require the use of increasingly sophisticated monitoring and modelling tools to identify hotspots of pollution and to determine whether or not the relevant air quality objectives will.be met in each area.

The NAEI is being used as an important source of data for the compilation of appropriate local inventories. Table 4.1 summarises the total 1999 emissions of the 8 priority pollutants covered by the AQS for ESWNI.

Table 4.1 Total UK Emissions of AQS for ESWNI Pollutants