Air quality strategy

The National Air Quality Strategy (NAQS) was first published by the Department of The Environment in 1997. It sets out a framework of standards and objectives for the air pollutants of most concern, with the aim of reducing the number and extent of episodes of air pollution, both in summer and winter. The eight priority pollutants are:

sulphur dioxide (SO₂)
particulate matter (PM₁₀)
nitrogen dioxide (NO₂)
carbon monoxide (CO)
lead
benzene
1, 3-butadiene
tropospheric ozone (O₃ )

The strategy identifies air quality standards for these pollutants based on the recommendations of The Expert Panel on Air Quality Standards (EPAQS[1]) guidance or, where this doesn't exist, the World Health Organisation (WHO). Specific objectives set out the required concentration limit of each pollutant, the degree of compliance with each standard expected and the relevant measurement timescale.

The Air Quality Strategy for England, Scotland, Wales, and Northern Ireland (2007)

The strategy was reviewed, updated and published by the Department for Environment Food and Rural Affairs (Defra) and the devolved administrations in July 2007. This was with close involvement from the Air Quality Forum – a group of stakeholders (including SEPA) and other Government Department representatives who act as a sounding board on air quality strategy in the UK.

The 2007 strategy is split into three volumes:

Volume One
The Air Quality Strategy for England, Scotland, Wales and Northern Ireland may be considered as the working strategy document. It lays out the UK Government and devolved administrations’ air quality objectives and describes measures selected to effect air quality improvements.
Volume Two
Sets out the scientific evidence bases underpinning the strategy, describes the methodology used in the baseline modelling and gives details of individual pollutant emissions inventories. It also contains an assessment of the policy measures which were considered and the Regulatory Impact Assessment (RIA).
Volume Three
An economic analysis to inform the review of the Air Quality Strategy, this volume includes the updated third report of the Interdepartmental Group on Costs and Benefits (IGCB) and presents the economic methodology and analysis used throughout the development of the strategy.

The full strategy can be accessed on the Defra website:

Air Quality Strategy for England, Scotland, Wales and Northern Ireland (2007)

The main differences between the 2007 strategy and previous strategy documents can be summarised as follows:

Particulate matter

As a result of on-going research, it has been recognised that it is likely that human health effects are more likely to be closely correlated with fine particulate matter (PM), referred to as PM_2.5 than with the coarser PM₁₀ fraction. As a result of this, PM_2.5 is included in the strategy for the first time. The Scottish annual objective is set more stringently compared to the rest of the UK. In addition, the concept of exposure reduction is introduced for the first time in recognition that fine particulate matter has no 'no effect' exposure threshold. As a result of this, it is beneficial, in terms of health, to reduce human exposure as a percentage of a starting baseline over a wide area, rather than specifically focus efforts on local “hot spots”. This should not, however, be taken to mean that the PM₁₀ fraction is harmless. This links closely to the requirements of the new Directive on ambient air quality and cleaner air for Europe:

Ambient Air Quality and Cleaner Air for Europe Directive

Ozone (ecosystems)

A new objective for tropospheric ozone for the protection of vegetation and ecosystems has been introduced. This UK wide target is for 2010 on a five year rolling average basis for the plant growing season. Note that this supplements and does not replace the pre-existing human health objective.

Consideration of new measures

A number of measures which could be taken to improve air quality were considered during the development of the strategy (discussed in Volume 3). These measures are in addition to existing air quality policies and were evaluated on the basis net present value (NPV) and divided into three categories:

Measures to be considered;
Measures requiring additional work;
Measures no longer under immediate consideration;

The three measures which were identified as having the best NPV were:

Incentivisation of the early uptake of new tighter European vehicle emissions standards (Euro Standards);
Increasing the uptake of low emission vehicles (LEVs);
Reducing the emissions from shipping.

All of these measures will require significant national and international agreement in terms of implementation.

Legal context

It should be noted throughout that the strategy documents referred to above are policy documents: they are not legislation. Primary legislation flows from the EU. The strategy takes cognisance of EU legislation but is free to tailor air quality improvement measures and even to alter standards, targets and objectives as long as they are at least as stringent as the EU requirements. In turn, there is a requirement for EU Directives to be transposed into Scottish law via Scottish statutory instruments with the same restrictions.

[1] this committee is to be merged with The Committee on Medical Effects of Air Pollutants