Download Environmental Accounts on Air Emissions QMI

February 2010
Issued by
Office for National Statistics,
Government Buildings, Cardiff
Road, Newport NP10 8XG
Media Office 0845 6041858
Business Area 0163 3456080
[email protected]
Summary Quality Report for Key Topics Within ONS
Environmental Accounts Data Releases: Air Emissions
1 Introduction
This report is part of a rolling programme of quality reports being introduced by the Office for
National Statistics (ONS). The full programme of work being carried out on Statistical Quality1 is
available on the National Statistics website. Summary Quality Reports are overview notes which
pull together key qualitative information on the various dimensions of quality as well as providing a
summary of methods used to compile the output.
This report relates to statistics for air emissions, which is a key topic within the UK Environmental
Accounts2 and aims to provide users with information on the usability and fitness for purpose of
these estimates.
For further information regarding the methods and terminology used in UK Environmental
Accounts2, please refer to the following publications:
•
•
•
•
UK Environmental Accounts2 (various editions)
United Nations: Handbook of National Accounting – System of Integrated Environmental
and Economic Accounting (SEEA 2003)3
Eurostat Environmental Accounts4
Eurostat: Compilation Guides5
2 Summary of Quality
2.1 Relevance
The degree to which the statistical product meets user needs for both coverage and content.
Air emissions data published in UK Environmental Accounts2 provide an analysis of air pollutants
broken down by emission type and industry. The maximum resolution of industrial disaggregation
used for air emissions data is 93 industries.
The following air emissions datasets are published as part of the UK Environmental Accounts2
release:
• emissions, atmospheric, summary
• greenhouse gas emissions and acid rain precursors by 13 industries
• greenhouse gas emissions by 93 industries
• acid rain precursors by 93 industries
• heavy metals by 93 industries
• other air pollutants by 93 industries
• road transport emissions by pollutants
• 68 sectors; energy, emissions and output
• air emissions bridge table, converting from a National Accounts basis to United Nations
Framework Convention on Climate Change (UNFCC)
Office for National Statistics, Information paper
1
•
air emissions bridge table, converting from a National Accounts basis to United Nations
Economic Commission for Europe (UNECE)
These estimates are updated annually each spring to include the most recent data published by
National Accounts and the National Atmospheric Emissions and Greenhouse Gas Emissions
Inventories (NAEI, GHGI). The data are compiled by contractors AEA Energy and Environment6,
who also compile the NAEI and GHGI for the Department for Energy and Climate Change (DECC)7
under the UK’s Kyoto obligations.
The air emissions accounts are compiled in accordance with SEEA 20033 which closely follows
national accounting standards set out in the United Nations, System of National Accounts 1993
(SNA 93)8.
The data cover the UK as a whole; there are currently no estimates at a regional level.
These data are used to provide information for policy makers and analysts. The main users of these
air emissions data, in Government, is the Department for Environment, Food and Rural Affairs
(Defra)9 although other departments such as the Environment Agency10, Department for
Transport11, DECC7 have also used this data in their analyses. Outside Government, research
organisations and academia use the data in their work on environmental impacts and sustainable
development.
2.2 Accuracy
The closeness between an estimated result and the (unknown) true value.
ONS air emissions data are produced by contractors AEA Energy and Environment6 who use
inventory data and a range of other sources including National Accounts Supply-Use Tables (SUTs)
as a framework for allocating emissions to industries. Therefore, two factors impact on the accuracy
of UK Environmental Accounts2 air emissions data - economic (ie the accuracy of the allocation of
emissions to particular industries) and the accuracy of the emissions factors used.
No work has been done at ONS to collate the impact of these different factors on the accuracy of
estimates of energy use. However, one dimension of accuracy is reliability which can be estimated
by measuring revisions to previously published data. The following table shows the extent to which
new information and methodology changes have caused data revisions between the most recent
and earlier publications.
Revisions to Green House Gas Emissions, percentage change compared with spring
2009 publication
%
1990 2000 2001 2002 2003 2004
2005
2006
2007
Spring 08
0.05
0.14
0.23
0.08 -0.04 -0.18
-0.45
-0.74
N/A
Spring 07
0.14
0.14
0.23
0.04
-0.08
0.00
-0.26
N/A
N/A
Spring 06
1.00
1.51
1.02
0.76
0.69
0.21
N/A
N/A
N/A
2.3 Timeliness and Punctuality
Timeliness refers to the lapse of time between publication and the period to which the data refer.
Punctuality refers to the time lag between the actual and planned dates of publication.
Air emissions data are published each spring with an eighteen month lag. For instance, 2007 data
were first published in spring 2009. This allows estimates to be based on most recent SUTs that
incorporate latest National Accounts information regarding the composition of the economy and
latest AEA Energy and Environment6 data used in the NAEI and GHGI.
Notification of the exact date on which this data are published each year is made public
approximately three months beforehand via the National Statistics Release calendar12. To date,
publication of these data has occurred without delay. In the unlikely event of a change to the preannounced release schedule, public attention should be drawn to the change and the reasons for
Office for National Statistics, Information paper
2
the change should be explained fully at the same time, as set out in the Code of Practice for Official
Statistics13.
2.4 Accessibility and Clarity
Accessibility is the ease with which users are able to access the data, also reflecting the format(s)
in which the data are available and the availability of supporting information. Clarity refers to the
quality and sufficiency of the metadata, illustrations and accompanying advice.
Air emissions data and text are presented in as clear a way as possible to ensure access to as wide
a range of readers as possible. Plain English definitions are given where technical terms are
unavoidable.
An overview of UK Environmental Accounts2 can be found at Focus on Environmental Accounts14
Tables, analysis and documentation are published in the spring and autumn editions of the UK
Environmental Accounts2
Tables, analysis and documentation are also published in United Kingdom: National Accounts (The
Blue Book)15
Time series data can be downloaded for free in .xls and .csv file formats from the UK Environmental
Accounts2 homepage on the ONS website.
General enquiries: queries on air emissions data, compilation methods, quality information or
difficulties finding the latest figures can be emailed to [email protected]
2.5 Comparability
The degree to which data can be compared over time and domain.
Methodological improvements are made to the data each year as part of an ongoing process of
review and are then applied to the whole time series. Therefore, data are consistent within each
publication but not from year to year. These improvements involve data relating to use of specific
emissions factors and sources, as well as incorporation of National Accounts and other data used
to establish the distribution of air emissions across the industries.
2.6 Coherence
The degree to which data that are derived from different sources or methods, but which refer to the
same phenomenon, are similar.
Each year the UK Environmental Accounts2 present estimates of pollutants directly emitted to the
atmosphere by each industrial sector. The figures are on a National Accounts basis - they include
emissions generated by UK households and businesses in the UK and emissions from UK
residents' transport and travel activities abroad. They exclude emissions generated by nonresidents transport and travel in the UK.
These data are therefore on a different basis from estimates published by DECC7 under the UK's
Kyoto Protocol obligations. The Kyoto basis covers emissions from UK territory only and excludes
emissions from international aviation and shipping. Two bridge tables, available on the UK
Environmental Accounts2 page of the ONS website, show the transformation process from National
Accounts to territorial basis.
3 Summary of Methods Used to Compile the Output
Atmospheric emissions are measured using a variety of methods dependant on the availability of
data. These methods include point source emissions which are directly measured such as those
recorded by road side measuring instruments. Emissions are also estimated using conversion
factors which link fuel use with its associated emissions, in other circumstances emissions data
may be modelled using information from other sources such as economic supply-use and inputoutput tables.
Office for National Statistics, Information paper
3
There are a wide range of pollutants that contribute emissions to the atmosphere. They include
greenhouse gases and substances that are directly toxic such as heavy metals. These pollutants
can be grouped according to their contribution to environmental themes such as climate change
and acid rain.
Greenhouse gases
The UK is required to report emissions under different international agreements for key air
pollutants covered by NAEI and greenhouse gases (GHG) covered by the UK GHG inventory. The
National Environmental Technology Centre (AEA Energy and Environment6) maintains the National
Atmospheric Emissions Inventory.
Changes in air emissions are compared to 1990 as this is the base year used in the Kyoto Protocol.
Although most greenhouse gas occurs naturally, some are man-made. Since the industrial
revolution, human activity has led to an increase in both the natural and man-made gases,
especially carbon dioxide. There is growing consensus that the rise in greenhouse gas emissions
has led to changes in the global atmosphere, so called global warming. The greenhouse gases
included in the air emissions accounts are those covered by the Kyoto Protocol.
Greenhouse gases included are: carbon dioxide, methane, nitrous oxide, hydrofluorocarbons,
perfluorocarbons and sulphur hexafluoride.
To aggregate the greenhouse gases covered in the accounts, a weighting based on the relative
Global Warming Potential (GWP) of each of the gases is applied, using the effect of carbon dioxide
over a 100 year period as a reference. This gives methane a weight of 21 relative to carbon dioxide
and nitrous oxide a weight of 310 relative to carbon dioxide. Sulphur hexafluoride has a GWP of
23,900 relative to carbon dioxide. The GWP of the other fluorinated compounds varies according to
the individual gas.
ONS air emissions accounts show greenhouse gas emissions in terms of carbon equivalent rather
than carbon dioxide equivalent. To convert from carbon dioxide equivalent to carbon equivalent it is
necessary to multiply by 12/44. This is the ratio of the atomic weights of carbon and carbon dioxide.
Conversion factors for greenhouse gas emissions are recommended by the Intergovernmental
Panel on Climate Change (IPCC) in their second assessment report.
Acid Rain Precursors
The term ‘acid rain’ describes the various chemical reactions acidic gases and particles undergo in
the atmosphere before being deposited as wet or dry deposition. When deposited the hydrogen
ions may be released causing acidification. These dilute acids damage ecosystems and buildings.
The emissions are weighted together using their relative acidifying effects. The weights, given
relative to sulphur dioxide, are 0.7 for nitrogen oxides and 1.9 for ammonia. This is a simplification
of the chemistry involved and there are a number of factors which can affect the eventual
deposition and effect of acid rain. There may be an upward bias on the weights of the nitrogenbased compounds in terms of damage to ecosystems.
The gases covered are sulphur dioxide, nitrogen oxides and ammonia.
Heavy Metals
Emissions of heavy metals can affect human and animal health. In particular, the immune,
metabolic and nervous systems are affected. Some heavy metals are suspected or have been
proven to be carcinogenic. Heavy metals impact on the environment in areas such as aquatic and
terrestrial ecosystems, metals may accumulate in mesofauna and macrofauna such as birds and
mammals and agricultural products through heavy metal input to arable soils.
Heavy metals included are: arsenic, cadmium, chromium, copper, mercury, lead, nickel, selenium,
and zinc.
Other pollutants
Office for National Statistics, Information paper
4
Other pollutants included are benzene, non-methane volatile organic compounds (NMVOC) and 1,3
butadiene which are considered carcinogenic. Carbon monoxide which is toxic in high
concentrations and PM10s. PM10s are smoke particles, less than 10 microns in diameter that have
been linked to physiological damage.
Attributing emissions to industrial sectors
NAEI projections of future emissions are an increasingly important requirement for UK Government
policy-making. National estimates of emissions are calculated across all economic sectors, eg
industry, domestic use. The disaggregation of national estimates of emissions to industrial sectors
is based upon an initial disaggregation provided by AEA Energy and Environment6.
Emissions are estimated by multiplying fuel consumption by emissions factors and adding releases
unrelated to fuel use such as methane arising from landfill and collieries.
The NAEI data are used to identify the main processes and industries responsible for the
emissions. These are then allocated to individual sectors on the basis of information from a variety
of sources. For example, emissions from diesel use by Heavy Goods Vehicles are allocated to
sectors using vehicle mileage data from Defra9. Expenditure information is also used, for example
emissions arising from the use of various industrial coatings (eg general industrial, heavy duty and
vehicle refinishing) are allocated to relevant sectors in proportion to each sector’s expenditure on
paints, varnishes and similar coatings, printing ink and mastics, using National Accounts InputOutput supply and use tables as the main source.
4 References
1
Title of Reference
Statistical Quality
2
UK Environmental Accounts
3
United Nations: Handbook of
National Accounting Integrated Environmental and
Economic Accounting
Eurostat Environmental
Accounts
4
5
6
7
8
9
10
11
12
13
13
15
Eurostat Compilation Guides
AEA Energy and Environment
Department for Energy and
Climate Change (DECC)
United Nations System of
National Accounts 1993 (SNA
93)
Department for Environment,
Food and Rural Affairs
(Defra)
The Environment Agency
Department for Transport
National Statistics Release
Calendar
Code of Practice for Official
Statistics
Focus on Environmental
Accounts
United Kingdom: National
Accounts (The Blue Book)
Website Location
http://www.ons.gov.uk/about-statistics/methodology-andquality/quality/index.html
http://www.statistics.gov.uk/statbase/Product.asp?vlnk=3698
http://unstats.un.org/unsd/envaccounting/seea.asp
http://epp.eurostat.ec.europa.eu/portal/page/portal/product_results/sea
rch_results?mo=containsall&ms=Environmental+Accounts&saa=&p_a
ction=SUBMIT&l=us&co=equal&ci=,&po=equal&pi=,
http://epp.eurostat.ec.europa.eu/portal/page/portal/statistics/themes
http://www.aeat.co.uk/cms/
http://www.decc.gov.uk/
http://unstats.un.org/unsd/sna1993/introduction.asp
http://www.defra.gov.uk/
http://www.environment-agency.gov.uk/
http://www.dft.gov.uk/
http://www.statistics.gov.uk/ReleaseCalendar/currentreleases.asp
http://www.statisticsauthority.gov.uk/assessment/code-ofpractice/index.html
http://www.statistics.gov.uk/focuson/environmental/
http://www.statistics.gov.uk/statbase/Product.asp?vlnk=1143
Last revised: February 2010
Office for National Statistics, Information paper
5