Memorandum submitted by Dr Gary
Fuller, Ben Barratt and Dr David Green, Environmental Research Group, King's
College London
(AQ 16)
Summary
· We have concerns about the current UK monitoring systems with
respect to their ability to support effective policy interventions in order to meet
EU Limit Values.
· The current UK monitoring system is designed to provide trends in
regulated pollutant concentrations and is limited in its ability to explain the
mechanisms behind such trends.
· A lack of understanding of air pollution sources and their linkages
to ambient concentrations has been underlined in recent years by a divergence
of predicted emissions reductions and measured concentrations.
· We therefore recommend that the UK monitoring system be expanded to
include targeted long-term monitoring in urban centres across the UK
specifically designed to further understanding of the sources and behaviour of
regulated pollutants, particularly the components of particulate matter (PM)
and NO2.
· Such monitoring will also be essential in order to assess the
effectiveness of air quality management policies.
About us
1. The Environmental Research Group at King's
College London is one of the UK's leading institutes in urban air quality
assessment. Focusing mainly in London and the south east we run air quality
monitoring networks on behalf of local authorities and Defra including the
London Air Quality Network (see www.londonair.org.uk).
We undertake air quality modelling to support air quality policy and
interventions on behalf of the Greater London Authority / Transport for London
and local authorities. We are also active in research into the sources of urban
air pollution and their health effects. The National Audit Office interviewed our
Director, Professor Frank Kelly, on 2nd October 2009 regarding the
understanding of air pollution health effects. Our comments here will therefore
not address this area but focus instead on UK monitoring systems.
UK monitoring systems used by Government
2. We have concerns about the current UK
monitoring systems with respect to their ability to support effective policy
interventions in order to meet EU Limit Values. By submitting modelled air
pollution concentrations to the EU the UK Government is only obliged to have
half the standard number of monitoring sites required by the EU Air Quality
Directive (EC, 2008). Whilst the use of modelling information in this way
enables better spatial coverage of air pollution in the UK, the reduced number
of monitoring sites may leave the UK's national monitoring networks vulnerable
with respect to their ability to:
· Represent urban
background and roadside concentrations in many areas of the UK.
· Provide sufficient
understanding of pollution sources to direct policy and to enable changes in
these pollution sources to be tracked over time.
· Determine the
efficacy of air quality management interventions.
3. In London and the south east of the UK the
coordination of local authority and national measurements by King's has led to
a cohesive network of densely distributed monitoring sites, representing the
range of pollutant exposures in the region with sites in kerbside, roadside,
industrial, urban background, suburban and rural locations. Such cohesive
networks are generally absent from other cities in the UK and many large urban
areas do not have representative coverage of background and near road
monitoring sites, for instance the UK Automatic Urban and Rural Network has
only one roadside monitoring site in Greater Manchester (Bury).
4. By necessity the current design of the AURN
has to ensure compliance with directive requirements. We would not advocate
simply doubling the air quality monitoring sites used by Government, instead
national monitoring programmes need to be targeted towards understanding
sources in order to inform and track the progress of air quality management
policies. More comprehensive analysis of measurement data is then required to
ensure that the full value of such targeted measurement networks is realised.
5. A lack of understanding of air pollution
sources and their linkages to ambient concentrations has been underlined in
recent years by a divergence of predicted emissions reductions and measured
concentrations. For instance, it is unclear why current polices to decrease PM10
concentrations are not yielding the desired results across Europe
(Harrison et al., 2008) and, despite European and London specific measures,
primary PM10 from within London increased between 1998 and 2003
(Fuller and Green, 2006). Further, progress towards reducing roadside
concentrations of NO2 have been confounded by changes in the
emissions of primary NO2 (Carslaw, 2005; AQEG, 2007) that were not
anticipated in emissions models. These changes in emissions of primary PM10
and primary NO2 were first detected in London using the dense
measurement network uniquely available in the capital. Outside London
deficiencies in monitoring networks make it difficult to detect and quantify
these new source trends. The UK's approach with respect to the number of
monitoring sites for Directive compliance may therefore leave us vulnerable to
detecting and understanding emission trends.
6. A simple network design to enable separation
and quantification of pollution sources was proposed by Lenschow et al., (2001)
for the understanding of PM10 sources; however this network design
has applicability for other pollutants. The so-called Lenschow approach
identifies monitoring sites to represent exposure at the different location
types and sources can be separated by difference. For example, 'roadside minus
background' concentration gives the contribution from a road or 'background
minus rural' gives information about sources across an urban area and so-forth.
Establishing and maintaining such site pairings allows sources to be tracked
over time and augmenting the UK monitoring networks in this way may increase
the source information that they are able to provide. Such separation of
pollution concentrations by source is especially important for the
understanding of airborne particulate matter (PM) where different pollution
sources give rise to particles with different chemical and physical properties
which are in turn likely to have different human health effects.
7. Only limited UK measurements are available on
the composition of PM. Although Defra's networks measure particle composition
in rural areas this does not have high time resolution necessary to inform
Limit Value compliance, emission inventories and modelling. The UKs'
measurement of urban PM composition is focused on London and is one of the few
examples of the application of a Lenschow design. However the measurement of PM
composition in the UK does not include sufficient chemical species to allow the
mass concentration of PM to be fully accounted for using 'mass-closure'
approaches. We are seeking to control a pollutant without sufficient
information on its composition and sources. For instance, are increases in
primary PM10 in London due to tailpipe emissions or tyre and brake
wear? Issues around our control of PM10 concentrations have been
bought to the fore with the recent EU Commission decision on the UK's time
limit extension but there have been few systematic measurements of the complete
mass of urban PM10 composition since those carried out in London and
Birmingham between 2000 and 2002 (Harrison et al., 2004). Additionally, there
is no national programme to measure urban PM2.5 composition despite
the new EU exposure reduction obligation. Without measurements of PM2.5
composition now, in the reference years, it will be difficult to direct policy
and determine changes over the ten year exposure reduction period. This
approach contrasts with our near neighbours where a systematic €1m programme to
measure PM2.5 and PM10 composition has just begun in
Paris to expressly inform air pollution management strategies (see http://www.londonair.org.uk/london/reports/AirParif_PM2%205_Study.pdf)
8. Targeted monitoring and analysis of
measurement data is also required to provide a level of accountability in air
quality management policy, i.e., did a specific policy lead to identifiable
improvements in air quality (and also in adverse health impacts) and was this
improvement cost effective? If not, why not and how could it be improved to
make it more cost effective (HEI, 2003)? Carrying out such accountability
studies is a complex task given the wide range of influences on air quality
independent of the effects of the policy, and requires targeted monitoring
strategies. A recent example where monitoring networks were deficient was the
London Congestion Charging Scheme (CCS). An accountability study to assess the
effects of the CCS on air quality was very limited in success as existing
monitoring was insufficient to isolate the effects of a decrease in traffic
numbers and congestion from underlying trends and meteorology (Atkinson et al.,
2009). In contrast, a bespoke targeted measurement programme has been funded by
Transport for London to determine pollution changes arising from the London Low
Emission Zone.
9. Many air quality management policies such as
fleet renewal have gradual effects. Therefore, it is essential that targeted
monitoring programmes or those monitoring of non-regulated pollutants (such as
PM composition or O3 precursors) be carried out over the long-term.
Long-term monitoring is also required to ensure that improvements are sustained
over time and not eroded by unexpected changes. These targeted monitoring
strategies will be essential if the UK is to meet EU Limit Values for NO2
and PM10 given the increasingly fragile reliance on vehicle
emissions reductions. The cost of measurement programmes may be small compared
to the cost of interventions to improve air pollution. Without a fuller understanding
of the behaviour and nature of pollutants, such as NOX and PM10,
effective and efficient policy decisions will be far more difficult to
formulate.
References
10. Air Quality Expert Group (AQEG), 2007. Trends
in primary nitrogen dioxide in the UK. Defra, London.
11. Atkinson R.W.,
Barratt B., Armstrong B., Anderson H.R., Beevers S.D., Mudway I.S., Green D.,
Derwent R.G., Wilkinson P., Tonne C., Kelly F.J., 2008. The impact of the
Congestion Charging Scheme on pollution concentrations in London. Atmospheric
Environment 43, 5493-5500
12. Carslaw,
D.C., 2005. Evidence of an increasing NO2/NOX emissions
ratio from road traffic emissions. Atmospheric Environment 39, 4793-4802.
13. European Commission (EC) 2008. Directive
2008/50/EC of the European Parliament and of the Council on ambient air quality
and cleaner air for Europe. Commission of the European Community, Brussels.
14. Fuller, G. W. and Green D., 2006. Evidence for
increasing primary PM10 in London. Atmospheric Environment 40,
6134-6145.
15. Harrison, R.M., Jones, A.M., Royston, G.L.,
2004. Major component composition of PM10 and PM2.5 from roadside
and urban background sites. Atmospheric Environment 38, 4531-4583.
16. Harrison, R.M., Stedman, J. and Derwent, R.D.,
2008. New Directions: Why are PM10
concentrations in Europe
not falling? Atmospheric Environment 42, 603-606.
17. HEI, 2003. Assessing Health Impact of Air
Quality Regulations: Concepts and Methods for Accountability Research.
Communication 11, September 2003. Health Effects Institute, Boston, MA 02129-4533.
18. Lenschow, P., Abraham, H.J., Kutzner, K.,
Lutz, M., Preuβ, J.D. and Reichenbächer W., 2001. Some ideas about the
sources of PM10. Atmospheric Environment 35, S23-S33.
14 December 2009
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