Memorandum submitted by the Department for Environment Food and Rural Affairs (Defra) (AQ 24)

This evidence has been provided in consultation with Department for Transport (DfT), Department of Health (DoH) and the Health Protection Agency (HPA).

Short Bulleted Summary of submission

Air quality in the UK has improved significantly over recent decades, but improvements are now levelling off for key pollutants and are increasingly costly to achieve.

Notwithstanding these improvements, air quality remains a significant health issue, particularly in urban areas, and reduces the life expectancy of the UK population by an average of 7-8 months, with social costs estimated at 9-21 billion per year. This excludes additional health costs that cannot currently be quantified. Air pollution also affects ecosystems and can lead to loss of biodiversity.

In common with many other Member States, the UK is not yet meeting in full European obligations or UK Air Quality objectives for particulate matter (PM10) and nitrogen dioxide (NO2)

Road transport and large combustion plant (power stations, refineries) are the key UK-based sources of overall pollution emissions but urban exposure are dominated by transport emissions. London generally has the highest levels of air pollution, but levels exceed European Limit Values for NO2, in particular along main roads in other major urban areas as well.

EU legislation; the Air Quality Strategy for England, Scotland, Wales and Northern Ireland and Local Air Quality Management provide the framework for delivery of improvements in air quality. The UK has submitted an application for additional time to meet EU limit value deadlines for PM10 and work is in hand on measures to help the UK meet EU obligations on NO2 by 2015.

The National Air Quality strategy provides the framework for regular review of air quality in the UK including health impacts and possible action for continued improvements in air quality. Looking to the future, links with climate change will be increasingly important to ensure that any measures taken will maximise the benefits to both areas.


1. Air quality has improved in the UK over recent decades. Levels of most pollutants are declining significantly, driven primarily by domestic and international legislation; legal limits are met across 99% of the country. The Environment Act 1995 requires the Government to set out a strategy for improving air quality in the UK. The first Air Quality Strategy for England, Scotland and Wales (later versions included Northern Ireland) was published in 2000 and was most recently revised in 2007. This set objectives for a number of different pollutants that have impacts on human health and or ecosystems. The key pollutants in the strategy are sulphur dioxide (SO2), particulate matter (PM10 and PM2.5), ozone (O3) polycyclic aromatic hydrocarbons (PAHs), benzene, 1,3 butadiene, carbon monoxide (CO) lead, ammonia, and oxides of nitrogen (NOX) including nitrogen dioxide (NO2). Many of these objectives are now reflected in EU legislation.

2. The UK is not meeting air quality strategy objectives for NO2 and PM10. Breaches of EU obligations for other pollutants such as SO2, PAHs or benzene are uncommon and usually associated with activities in a particular location. Excessive deposition of nitrogen as a result of ammonia and NOX emissions remains a threat to ecosystems.

3. Levels of particulate matter (from road transport, stationary fuel combustion, tyre and brake wear and construction and quarrying) remain above legal limits in a very small number of (mainly urban) areas in London. However health evidence suggests that there is no "safe" level for fine particulate matter, and so health benefits (in terms of reduced mortality and morbidity) can be achieved through reductions in population exposure below current legal limits. Concentrations of NO2 remain above the EU limit value (and UK objectives) at about a third of major roadside sites in urban areas. The recent decline in concentrations of NO2 is now levelling off and further research is needed to understand why this is the case. Where improvements are most needed (notably urban areas near busy roads) these are increasingly challenging and expensive to achieve.

4. Peak ozone episodes (summer smogs) have decreased due to pollution control in the UK and Europe, but background ground-level ozone levels are rising. In addition to causing health effects, ozone damages both crops and natural ecosystems, and is a powerful greenhouse gas.

Health and environmental impacts of poor air quality

5. Defra works with the Health Protection Agency, Department of Health and other Government Departments to maintain and develop methodologies for assessing air quality impacts on health and the environment.

6. The quantified health impacts of air pollution in the UK are valued in accordance with Treasury guidelines and follow the approach set out by the Interdepartmental Group on Costs and Benefits (IGCB) in Volume 3 of the Air Quality Strategy (2007). A monetary cost benefit analysis (CBA) forms a major part of the overall assessment of measures to improve air quality including those set out in the Air Quality Strategy 2007. The monetary assessment of benefits is based on an impact-pathway approach that follows a logical progression from emissions through dispersion, concentration and exposure to quantification of impacts and their valuation. The benefits are then compared on a consistent basis with the estimated costs associated with the implementation of each policy measure under consideration.

Overview of health impacts from air pollution

7. Advice to Government on the health impacts of air pollutants is provided by the Committee on Medical Effects of Air Pollutants (COMEAP). Several members of COMEAP have contributed to the development of the air quality guidelines published by the World Health Organization (WHO) over the years (WHO, 1987; 2000; 2005). The WHO air quality guidelines form the basis for the European limit values set out in the UK's Air Quality Strategy.

8. Extensive research considered by COMEAP has shown that both short-term and long-term exposure to air pollution can have effects on health. Of the nine air pollutants covered in the UK's Air Quality Strategy (2007) the effects of particulate pollution have dominated the overall impact of air pollution on health. The available evidence shows that day to day variations in concentrations of airborne particles are associated with day to day variations in a range of health effects. These include deaths, admissions to hospital for the treatment of both respiratory and cardiovascular diseases and asthmatic symptoms. In addition to these effects there is evidence that long-term exposure to particulate air pollution is associated with a decrease in life expectancy. These associations are believed to be causal.

9. The available health evidence suggests that there is no "safe" level for fine particulate matter (measured as PM2.5). Therefore there are further benefits to health that can be achieved through reductions in population exposure below current legal limits. The Air Quality Strategy 2007 sets out an 'exposure reduction' approach for PM2.5. This seeks further reductions in the health effects of air pollution by providing a driver to improve air quality everywhere in the UK rather than just in a small number of localised hotspot areas, where the costs of reducing concentrations are likely to be exceedingly high. This approach will act to make policy measures more cost-effective and is more likely to maximise public health improvements across the general population. This approach was adopted for PM2.5 by the EU in Directive 2008/50/EC on ambient air quality.

10. Air pollution is currently estimated to reduce life expectancy by an average of 7-8 months across the UK population with estimated equivalent costs of between 9 billion and 20 billion. However there are important uncertainties associated with the quantification and valuation of health impacts. These uncertainties are set out in full in Volume 3 of the Air Quality Strategy 2007.

11. Significantly of all the common air pollutants covered in the Strategy (2007), the evidence on the health effects associated with both short-term and long-term exposure to NO2 has been inconsistent. Whilst the health effects of particulate pollution are well understood, those resulting from NO2 are less clear. The available evidence suggests that the reported effects of NO2 might be due to exposure to particulate pollution owing to the close correlations between their concentrations and similarity of sources.

12. Previous attempts by COMEAP to quantify the possible effects of exposure to NO2 have not been successful as COMEAP did not regard the available evidence sufficient enough for quantification (DH, 1998); and the available studies have also had difficulties in disentangling the effects of NO2 from those of particles and other pollutants/factors (COMEAP, 2009). As a result, Defra (and DH) has been unable to assess the direct health benefits for measures to control NO2 and no direct health benefits have been included in the main cost-benefit analyses for measures assessed in the Air Quality Strategy (2007). Only a sensitivity analysis is presented for the effects of NO2 on respiratory hospital admissions. The 1998 report by COMEAP suggested a concentration-response function that could be used in sensitivity analyses to illustrate the possible size of the effect of short-term exposure to NO2 on respiratory hospital admissions. It should be noted that NO2 can be converted to nitrate which is a component of particle aerosols; the indirect effect of NO2 via nitrates (secondary particle) on mortality, as part of this fine particle mixture (measured as PM2.5), is currently quantified.

13. COMEAP acknowledge that further work is required in order to understand the health effects associated with exposure to NO2 and is currently in discussion with the Health Protection Agency in developing a programme of work in this area.

14. There is currently an underestimation of the full range of possible health benefits that could be attained from policy measures to improve air quality, because it has not been possible to quantify all health outcomes. Work to review the evidence is ongoing and it is expected that this would lead to an increase in the number of health outcomes identified. Inclusion of other health effects in the central analysis would increase the monetised health benefits that could result from measures targeted at reducing concentrations of air pollutants in the UK.

15. There is some evidence from limited UK studies to suggest that air pollution exposure is higher amongst some communities who rate poorly on social deprivation indices (Defra, 2007). Although this work was limited in scope (it covered only five urban areas in the UK), it illustrates possible health inequalities.

Overview of the impact of air pollution on ecosystems

16. There is a large body of literature demonstrating that air pollutants can affect aquatic and terrestrial ecosystems. Concern began in the 1970s with the identification of problems caused by acid rain and continues today with the issues of eutrophication and ground-level ozone.

17. An indication of the potential for effects of pollutants on the environment to occur is provided via the critical load concept. A critical load is an estimate of the exposure to one or more air pollutants, above which there is risk of damage to certain sensitive elements of the environment. If the amount of deposition is greater than the critical load for that habitat, an exceedance is reported. Exceeding critical loads does not necessarily indicate that damage has occurred, but it indicates the potential for damage to occur.


18. Acidification of soils and waters can be caused by deposition of sulphur, nitrogen (from emissions of NOX and ammonia) or hydrochloric acid (or a combination of these pollutants). Emission controls have reduced sulphur dioxide emissions by over 90% from their peak value in the 1950s, resulting in reduced concentrations of sulphur and levels of acidity in the atmosphere, soils and freshwater.

19. There has been a reduction in the area of terrestrial broad habitats exceeding critical Loads for acidity from 71% of ecosystem area using 1996-98 acid deposition, to 58% using deposition data for 2004-06; this is predicted to reduce to 40% in 2020. Current critical load exceedences for acidity are mainly due to the deposition of nitrogen rather than sulphur. Typically, most of the deposited nitrogen is accumulating in soils and vegetation, and relatively little is currently contributing directly to acidification, but significant leaching to surface waters is occurring in higher deposition areas, and in particularly in catchments with sparse soils.

20. Since the problem was identified in the 1970s, UK and International policy action has achieved considerable success in managing acid deposition. Acid deposition has been greatly reduced and the acidity of soils and acidified surface waters has declined. Ecological recovery of these habitats is underway but soils and freshwaters in some regions remain acidified and the legacy of previous emissions, land use and climate change may limit the extent of the recovery. Further reductions in the emissions of sulphur may be required to aid ecological improvement.


21. Eutrophication from atmospheric deposition in the UK is caused by the emissions of nitrogen oxides and ammonia. Emissions of nitrogen oxides have decreased by 50% since 1970, with a corresponding 50% reduction in air concentrations of nitrogen oxides. Emissions of ammonia are only reliable from 1990 onwards, since when they have decreased by 24%, although there is large annual variability, masking any overall trend. Concentrations of ammonia have changed little over the last decade.

22. Despite the large reduction in emissions, total deposition of nitrogen has changed little. This is due to changes in the chemistry and removal of nitrogen compounds accelerating the removal from the atmosphere over twenty years of monitoring. Thus a larger proportion of nitrogen emissions are deposited in the UK than occurred twenty years ago. At sites in the UK where nitrogen deposition exceeds the capacity of the vegetation and soil to sequester inputs, nitrate is leaching into surface waters and has the potential to stimulate algal growth and affect species composition. In the terrestrial environment, changes in species composition have been observed close to sources of ammonia, and in the national surveys (such as the Countryside Survey which while showing significant impacts up to 2000, suggest no worsening of conditions thereafter). Controlled experiments also show reductions in species composition with nitrogen addition, especially for ammonia treatments. Currently, 60% of all sensitive habitat areas sensitive to eutrophication from nitrogen deposition exceed the critical load for nutrient nitrogen. This figure is predicted to decrease to 49% by 2020.

23. Eutrophication problems are being addressed, and while there has been a reduction in emissions and concentrations of nitrogen oxides, it is recognised that further policy action is required to reduce nitrogen emissions, and especially ammonia to prevent further damage and allow recovery of some plant communities to begin.

Ground-level ozone

24. Biological indicators of ground-level ozone show that concentrations continue to exceed thresholds for effects on sensitive species. Current ozone exposures exceed critical thresholds for effects on crops, forests and semi-natural vegetation over substantial areas of the UK. Background concentrations of ozone in the northern hemisphere have now increased to a level where exposure to ozone may cause adverse effects on vegetation. These effects are most likely to occur in crops grown in the southern areas of the UK during spring and summer. It has been estimated that ozone reduces the yield of wheat grown in southern Britain by 5% to 15%, equivalent to a reduction in national yield in 2000 of approximately 2 million tonnes. Ground-level ozone also contributes to global warming indirectly by reducing carbon take up by vegitation as well as being a greenhouse gas in its own right.

25. Policy action to reduce European emissions of the precursor gases which form ozone have successfully reduced peak ozone concentrations in the UK. However, emissions throughout the Northern Hemisphere are causing increasing background levels; control of emissions of ozone precursors at the hemispheric scale is therefore required.

Assessment of air quality

26. UK monitoring of air quality is undertaken for a number of reasons but the pollutants monitored, the methods used and the location and number of monitoring sites mainly follow requirements of EU legislation. "Directive compliance" monitoring makes up the vast majority of the revenue spend on monitoring activities, and takes up over 50% of the total evidence and research budget for air quality in Defra. Monitoring is also undertaken for other reasons, such as the maintenance of long term and policy relevant datasets (e.g. the black smoke network where some data go back to the 1920s). By applying the principle of "measure once, use many times" all data from our monitoring networks support a range of activities even though the design of the networks is, by and large, prescribed in legislation.

27. All air quality monitoring data, current and historic, gathered by Defra is made publicly available through the national air quality archive - - which is updated hourly from our automatic systems. All of our monitoring activities are outsourced through fully competitive tendering processes to ensure high value for money.

28. Local authorities also undertake air quality monitoring for their own purposes and to inform the process of local air quality management. The location of monitors, the methods used and the quality control systems used may not be of the standard required by the European Directives and so these data are not generally reported to the Commission. However, where the requirement of the Directive coincide with local authority monitoring, these sites can be "affiliated" into the national network: the local authority retains ownership of the site and the equipment and Defra takes on the maintenance and quality control. In this way we are able to obtain data in a more cost effective manner; some 53% of the Automatic Urban and Rural Network (AURN) is made up of affiliated sites. The extent to which local data can be used in the centre to assist in delivery of air quality improvements is under review and consideration is being given to the best use of this data at the centre.

29. The Ambient Air Quality Directive also offers Member States the option of reducing the prescribed number of monitoring stations if supplementary assessment methods, are also reported. The UK makes full use of this option as the national model provides far greater spatial coverage than monitoring alone as well as saving around 2.5 million annually. The model is tested against monitoring data and comes well within the required data quality objectives laid down in the Directive.

30. Monitoring data are critical to future policy development, as is predictive modelling, but they are both complex and have many inherent uncertainties. For example, there is evidence from the monitoring network to suggest that roadside concentrations of air pollution are not falling in line with emissions projections (this is being seen in other Member States as well). Defra is conducting research to understand the causes of this and to improve reliability of modelling. Research is conducted to improve our evidence base on air quality and to inform how best to secure future improvements.

Policies to improve air quality and meet EU obligations

31. The new ambient air quality directive (2008/50/EC) must be transposed into national legislation by June 2010 and the UK is on track to achieve this. This Directive consolidates and simplifies most of the existing EU legislation on ambient air quality, setting legally binding limits for key pollutants to protect public health and ecosystems; and introduces a new control framework for fine particulate matter based on exposure reduction. It also provides for additional time to meet the limit values for PM10 and NO2, subject to Commission approval of detailed plans setting out how this would be achieved. This is in recognition of the difficulties nearly all Member States have had in meeting the original deadlines.

32. Since 2005 the UK has reported exceedences of the PM10 limit value in 8 UK zones (including London) and in April 2009 the UK submitted an application to seek exemption from the obligation to comply with this until 2011 as provided under article 22 of Directive 2008/50/EC. National projections based on a 2005 baseline year suggested that on the basis of current measures compliance would be achieved across all zones by 2011. This reflects the fact that air quality in the UK is generally good and PM10 limits have been met across 99% of the UK. Since this submission, the national 2008 assessment reported compliance in all zones except London and updated national projections show that we should achieve compliance with the limit value across the whole UK by 2010.

33. The Commission published its decision on the notification on 11 December, as it has also done for several other Member States. Whilst this was disappointing in relation to London, Government is confident that it can respond to the questions raised by the Commission and will resubmit its application with further information as necessary, working closely with the GLA. The Mayor of London published his draft air quality strategy in October 2009; and this increases our confidence in our ability to meet particulate matter limits across London by 2011.

34. Meeting EU limits for NO2 in the remaining areas of exceedences presents, a much more significant challenge, requiring additional action in particular to limit emissions from the transport sector in urban areas. The limits for NO2 come into force in January 2010 and the UK faces infraction if they are not met or we are unable to demonstrate how they will be met by 2015. This is a risk shared with nearly all other major Member States. Latest estimates for this pollutant suggest that on the basis of current measures alone the UK would not meet EU limit values for this pollutant by either 2010 or 2015. For example Defra projections suggest that without additional measures some 500km of roads mainly in London but also in other major urban areas in the UK, would breach the NO2 annual mean limit value in 2015). Defra is working with DfT and other stakeholders to identify measures to reduce NO2 pollution and prepare an application for time extension to meet the EU limit value for this pollutant by 2015.

35. The most significant levels of exceedence for NO2 are in London and the London Mayor's draft air quality strategy provides some useful measures but their impacts need to be fully quantified and understood and this is not possible without further analysis from the GLA. Separately from this, work is in progress to deliver the Government commitment made in January 2009 that a regulatory mechanism would be put in place to ensure air quality limits are met around an expanded Heathrow airport. No additional capacity would be released until the limits are met.

Vehicle Emission Standards

36. Emissions standards (called EURO standards) for new vehicles and the regulation of fuel quality to reduce air pollution from vehicle emissions are a particularly important means of improving ambient air quality. These have led to significant reductions in particulates especially since the early 2000s. Further reductions should be achieved thanks to later Euro Standards (Euro 5 and especially Euro 6) which impact in particular on emissions of NOX including NO2 but these will not have a significant impact until 2015 and beyond when Euro 6 becomes mandatory. Therefore other measures are needed in the short term to reduce pollution and to meet EU obligations. Measures under consideration by Government include exploring the feasibility of low emission zones outside London, retrofitment of pollution abatement technology to the most polluting vehicles (HGV and buses especially); incentivising the early introduction of euro standards, in particular Euro 6 when this becomes available. Other measures under review include measures to reduce road traffic through modal shift for example and to encourage the purchase of low and very low emission vehicles.

37. Many of these measures have significant cost implications which need to be carefully considered against the benefits. The 2007 UK Air Quality Strategy reviewed a number of possible measures and concluded that the most cost beneficial measures were to incentivise Euro standards; to promote low emission vehicles and to reduce emissions from shipping. Action on shipping will be implemented through international maritime legislation; implementation of the other measures is still under consideration as part of the work to apply for further time to meet the NO2 EU limit value.

Local air quality management in England

38. The Environment Act 1995 sets out requirements for local authorities to monitor and assess local air quality and to work towards the attainment of air quality strategy objectives where these are not met or at risk. The UK Government and the devolved administrations in Scotland, Wales and Northern Ireland are responsible for policy and legislative issues affecting air quality. Defra oversee local air quality management in England. Local Authorities have monitored air quality at district and borough level since the beginning of 2000 and have identified many locations where UK objectives have not been met. These are mainly in large urban areas such as London and major conurbations in the West Midlands the North West and Yorkshire but also in many smaller urban areas and market towns where narrow streets have restricted the dispersion of pollutants. In 2009 over 240 Authorities in the UK had declared an Air Quality Management Area for one or more of the UK objectives. For each of these areas the local authority concerned must prepare and implement an action plan to improve local air quality.

39. Guidance on preparing Action Plans and on measures to improve air quality is provided by Defra and the devolved administrations. Delivery of local air quality improvements is often reliant on district and county authorities and neighbouring authorities working together to identify the main sources of pollution and introducing complementary measures to improve air quality. Transport sources are commonly the most significant source of pollution locally. In 2009, the Department for Transport issued the latest round of Local Transport Planning Guidance, which strongly encourages local authorities to integrate their air quality action plan with their local transport plan. Similar approaches are recommended for minimising the negative impacts of land use development on air quality and climate change measures. Local air quality management arrangements are currently being reviewed to ensure they remain fit for purpose and capable of delivering local improvements to support the national objectives.

National Emissions Ceilings

40. Health and ecosystem impacts are also caused by air pollutants transported in large quantities across national boundaries. The EU national emissions ceilings directive (NECD) and protocols under the UNECE Convention on Long-Range Trans-boundary Air Pollution aim to address this by setting national emission ceilings for key air pollutants. The UK is currently on course to meet its NECD 2010 emission ceilings for SO2, VOCs and NH3. However, like many other European countries, the UK is currently projected to exceed its 2010 NOX ceiling by a small percentage with compliance expected by 2012. The situation is being closely monitored with a view to meeting the ceiling as soon as possible. The Gothenburg protocol, which like the NECD sets ceilings for key pollutants but also sets limit values for key emission sources, is currently being reviewed with a view to setting new ceilings to be achieved by 2020. The European Commission is also expected to publish some time in 2010 a proposal for revision of the NECD so as to set new, tighter ceilings for 2020.

Industrial emissions

41. UK legislative controls on emissions to air from industrial installations have been vital to improving air quality locally, nationally and internationally. In recent years, the larger industrial installations (now some 4,500 in the UK) have been subject to integrated pollution prevention and control (IPPC) under the eponymous European Directive[1] which requires emission limit values (ELVs) to be set for all likely significant emissions to any of the three environmental media. The regulator has to set ELVs on the basis of the use of best available techniques (BAT) which in turn are determined and regularly reviewed on the basis of technical and economic viability in the industry sector concerned. The BAT approach is also used in the regulation[2] under national legislation of air emissions from some 20,000 smaller industrial installations.

42. Other EU legislation dealing with waste incineration, large combustion plants and activities using solvents are met in the UK through the IPPC framework. EU legislation on petrol vapour recovery, paints formulation and the sulphur content of liquid fuels also provide controls upon industry (including the transport industry) relevant to air quality.

Future drivers

43. Growing population and increasing travel in some urban areas, linked with continuing pressures on development, make it difficult to reduce overall air pollution levels in the short term, particularly in major urban areas and along key infrastructure routes. On the basis of current impact assessment methodologies, the costs of measures specifically aimed at bringing forward expected air quality improvements can outweigh the health benefits.

44. Projected increases in summer heatwaves, such as that in 2003, as a result of climate change are expected to increase the frequency and severity of 'summer smogs'. In the UK, it was estimated that there were between 225 and 593 additional deaths brought forward due to increased ozone in the first 2 weeks of August 2003, compared to the same period in 2002. Similarly, for PM10 concentrations, it was estimated that there were 207 additional deaths. For England and Wales, the deaths due to air pollution accounted for 21-38% of the total reported excess deaths during the 2003 heatwave. Other potential climatic changes (higher rainfall, stronger and more prevalent south westerly winds in winter) may benefit local UK air quality. Any increase in burning of coal in the UK in existing combustion plants in the UK will impact negatively on air pollution despite existing and planned abatement measures. The Department for Energy and Climate Change announced in November 2009 that new coal-fired plants would need to incorporate carbon capture and storage which would bring air quality benefits in addition to meeting the primary aim of reducing CO2 emissions.

45. Globally, greater use of fossil fuels resulting from increased population and energy demand will impact on transboundary air pollution affecting the UK so continued efforts in international fora to drive down national emissions will be needed.

46. Given the many common emission sources, links with the climate change mitigation agenda will be increasingly important in maintaining and improving air quality so that local as well as global benefits are accrued. Influencing future UNECE and European Commission proposals as well as ensuring good co-ordination within Government including at regional and local level will be critical. In the short to medium term (to 2020-2030) one challenge will be to manage the risks of deterioration from increased biomass burning (which can lead to local increases in levels of particulates) as well as optimising synergies from energy efficiency measures, low carbon vehicles and increased use of non combustion renewable energy. Looking further, right out to 2050, the scale of carbon reductions that the UK has committed to means there should be significant co-benefits achievable for both air quality and climate change. The recent Pre Budget Report announcements on promoting low carbon transport will provide helpful incentives to support the growth in electric vehicles which will bring benefits for air quality on top of those for climate change mitigation.

15 December 2009

[1] Now 2008/1/EC. A proposed "recast" of this and related legislation was politically agreed in the Environment Council in June 2009 and stands to be finalised in mid 2010 after further consideration by the European Parliament.

[2] By local authorities in England and Wales and by the Scottish Environment Protection Agency and the Northern Ireland Environment Agency in their respective areas.