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BOC Immingham Dissolved Acetylene Project Environmental Statement: Vol. 2 Main Text
Assessment Methodology and Significance
Criteria
Legislation and Policy
Air Quality Strategy
6.5 The UK Government’s Air Quality Strategy (AQS) for England, Scotland, Wales and Northern
Ireland 22 provides details of national air quality standards and objectives for a number of local air
pollutants. These statutory criteria are defined in Regulations SI 2000/928 and SI 2002/3043.
6.6 The standards define the level of pollution below which health effects are unlikely to be
experienced even by the most sensitive members of the population. These are based upon the
recommendations of the Expert Panel on Air Quality Standards (EPAQS). The objectives are
targets for air pollution concentrations which take account of the costs and benefits of achieving
the standard. In the case of short-term targets, the permissible number of hours or days above the
objective concentration is also specified. The number of permissible ’exceedences’ is considered
when determining compliance with the short-term objectives over an annual period.
6.7 The AQS objectives also implement the requirements of European Directives on air quality. The
first European Community (EC) air pollution limit values were introduced in the 1980s. The
directives contain mandatory limit values that must be attained and more stringent, but nonobligatory,
guide values. In April 2008, the European Commission adopted a directive on ambient
air quality and cleaner air for Europe (2008/50/EC). This directive merged the previous Air Quality
Framework Directive and the first three daughter directives and introduced new objectives for
PM2.5. It has recently been transposed into UK Regulations (SI 2010/1001).
6.8 It should be noted that the UK air quality objectives only apply in locations where there may be a
‘relevant exposure’. These human health objectives are applicable where members of the public
may be exposed to pollutant levels for periods equal to or exceeding the averaging periods set for
these criteria. Locations of relevant exposure include building façades of residential premises,
schools, public buildings and medical facilities. Places of work (other than certain community
facilities) are excluded.
6.9 The air quality objectives for the protection of human health and for the protection of vegetation
and ecosystems, relevant to transport emissions, are presented in Table 6.1.
Ecosystems
6.10 The objectives set for the protection of ecosystems apply in areas that are:
� more than 20 km from towns with more than 250,000 inhabitants; or
� more than 5 km from industrial sources regulated under Part 1 of the Environmental
Protection Act 1990, motorways and built up areas of more than 5,000 people.
6.11 Nevertheless, the regulatory agencies have agreed with the countryside agencies that these
objectives (also referred to as critical levels) should be applied at all locations as a matter of
policy, and therefore they have been included in this study.
6.12 Critical loads for nitrogen and acid deposition have been set by the United Nations Economic
Commission for Europe (UNECE). A critical load is defined as a quantitative estimate of an
exposure to one or more pollutants below which significant harmful effects on specified sensitive
elements of the environment do not occur, according to present knowledge. Critical loads vary by
type of habitat and species. The critical load for nitrogen deposition (eutrophication) is given as a
range and is quoted in units of kg N/ha/year. A single critical load is quoted for acidification, in keq
H + /ha/year. The critical load for acidification considers both nitrogen and sulphur deposition fluxes.
5100935.404 Environmental Statement August 2011 71