1. Indicator

(a) Name: Emissions of greenhouse gases (GHG).
(b) Brief Definition: National anthropogenic emissions of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O).
(c) Unit of Measurement: Annual emission levels in gigagrams (Gg) of CO₂ equivalents; methane and nitrous oxide emissions are converted into CO₂ equivalents by using global warming potentials (GWP); annual percentage change in total GHG emissions beginning with 1990 as base year would provide trends and rate of change in emission levels for each Party to the Climate Change Convention.

2. Placement in the Framework

(a) Agenda 21: Chapter 9: Protection of the Atmosphere.
(b) Type of Indicator: Driving Force.

3. Significance (Policy Relevance)

(a) Purpose: This indicator measures the major anthropogenic emissions contributing to global warming.

(b) Relevance to Sustainable/Unsustainable Development: The main greenhouse gases (GHGs) are carbon dioxide (CO₂), methane (CH₄), nitrous oxide (N₂O). While there are natural emissions of GHGs, anthropogenic emissions have been identified as a source of climate change (IPCC Second Assessment Report, 1995) and are the subject of an international instrument (the UN Framework Convention on Climate Change). Such emissions are largely influenced by a country's energy use and production systems, its industrial structure, its transportation system, its agricultural and forestry sectors, and the consumption patterns of the population. Methane and nitrous oxide emissions are particularly influenced by a country's agricultural production, waste management, and livestock management.

Climate change results in part by the increased concentration of greenhouse gases in the atmosphere. At one level, global warming due to anthropogenic emissions of greenhouse gases can be said to have no adverse effect on ecosystems if the increase in global temperature is within 0.1^oC per decade, with a maximum total warming of 2^oC above the pre-industrial situation (IPCC, 1992). In this case, it is suggested that ecosystems can adjust or adapt to the temperature changes within these limits. The Intergovernmental Panel on Climate Change (IPCC) has worked out levels for the most important greenhouse gases that should lead to a stabilization of total GHGs at the no-adverse effect level. This is known as the accelerated policies scenario. However, given the increase in the atmospheric concentration of GHG from 280 ppmv in the pre-industrial period ( that is, before 1850) to 356 ppmv in 1994, the temperature increase may be occurring more rapidly and randomly than ever before. Based on the findings of three working groups, the IPCC says that the earth's temperature could rise by between one and 3.5 degrees Celsius by the year 2010; an average rate of warming probably higher than any in the last 10,000 years.

(c) Linkages to Other Indicators: This indicator is closely linked to many other socioeconomic and environmental indicators, for example, GDP per capita growth rate, annual energy consumption per capita, environmental protection expenditures, and expenditures on air pollution abatement.

(d) Targets: The objective of the Climate Change Convention (Article 2) is to achieve the stabilization of GHG concentrations in the atmosphere at a level that would prevent dangerous anthropogenic interference with the climate system.

(e) International Conventions and Agreements: The United Nations Framework Convention on Climate Change entered into force in March 1994 and, as of end January 1996, it had been ratified by 152 Parties. Article 4 of the Convention, among other commitments, calls for Annex I Parties to return by 2000 (individually or jointly) their anthropogenic emissions of carbon dioxide and other greenhouse gases not controlled by the Montreal Protocol to their 1990 level. Additionally, some Annex I Parties to the Convention have set national targets that go beyond those of the Convention. Based on a first compilation and synthesis of data requested from Parties (see doc. A/AC.237/81 and corr.1) only a few countries seem to be in a position to reach the stabilization target by 2000. These include the Czech Republic, Denmark, Netherlands, Switzerland, and the United Kingdom.

4. Methodological Description and Underlying Definitions

Greenhouse gases will contribute at varying degrees to global warming depending on their concentration and life horizon in the atmosphere and their heat absorptive capacities. Global warming potentials (GWP) are used for each gas (other than CO₂) as a weighting factor to calculate national GHG emissions in CO₂equivalents.

Emissions for CO₂, CH₄ and N₂O are estimated based on activity data from fuel combustion, fugitive fuel emissions, industrial processes, solvent use, agriculture, land use change, and forestry and waste. Emission levels are calculated using emission factors associated with emissions of each gas for relevant activities. A greater degree of international comparability has been achieved by using default emission factors proposed by the Intergovernmental Panel on Climate Change (IPCC). National emission factors have been used, whenever available, which has resulted in increased precision in national GHG emissions.

Proposed additional related indicators would include annual GHG emissions per capita, and annual GHG emissions per unit of GDP.

5. Assessment of the Availability of Data from International and National Sources

Thirty-one of the 38 Parties included in the Annex I to the Convention have submitted national communications containing detailed national GHG inventories. As part of the review process under the Convention, in-depth reviews of these national communications have been undertaken resulting in the collection of detailed information on GHG emissions by Annex I Parties. It is estimated that these Parties, as a group, are responsible for over 60% of total global GHG emissions annually.

As part of the review process of the Climate Change Convention, emission levels would initially be available only for Annex I Parties to the Convention (OECD plus EIT countries). By mid-1997, non-Annex I Parties will also start to submit first-hand information on their annual GHG emissions.

6. Agencies Involved in the Development of the Indicator

The lead agency is the United Nations Framework Convention on Climate Change (UNFCCC). The contact point is the Executive Secretary, Secretariat, UNFCCC; fax no. (41 22) 970 9034.

7. Further Information

First review of information communicated by each Party included in Annex I to the Convention. A/AC.237/81 and corr. 1.

In-depth review reports on individual countries.

1. Indicator

(a) Name: Emissions of sulphur oxides.
(b) Brief Definition: National anthropogenic emissions of sulphur oxides (SO_x) expressed as amounts of sulphur dioxide (SO₂).
(c) Unit of Measurement: Tonnes or 1000 tonnes; % change in emissions over time (for example, % change in emissions between 1980 and 1995). Proposed denominator: per capita, per unit of Gross Domestic Product (GDP), per unit of gross energy consumption.

2. Placement in the Framework

(a) Agenda 21: Chapter 9: Protection of the Atmosphere.
(b) Type of Indicator: Driving Force.

3. Significance (Policy Relevance)

(a) Purpose: The indicator is used to evaluate the environmental performance of national policies and to describe the environmental pressure in relation to air emission abatement.

(b) Relevance to Sustainable/Unsustainable Development: Anthropogenic sulphur oxide emissions are influenced by a country's industrial structure and energy consumption, which in turn is affected by both energy intensity and efficiency. The emissions are also influenced by the country's standard of pollution abatement and control and the use of clean production technology. They give an indication of human impact on the environment through production and consumption. Countries' efforts to abate sulphur oxide emissions are reflected in national policies and international commitments. Concrete actions include structural changes in energy demand (energy savings and fuel substitution) as well as pollution control policies and technical measures (for example, the installation of industrial desulphurisation facilities).

Together with nitrogen compounds, sulphur compounds are the source of environmental acidification. Anthropogenic sulphur oxides are predominantly emitted by energy production plants, followed by industrial combustion and industrial processes. Airborne emissions of sulphur oxides contribute to local pollution as well as to large scale pollution through long distance transport in the atmosphere.

Human exposure to sulphur oxides in the air contributes to respiratory morbidity and mortality. The population subgroups most sensitive to sulphur dioxide include asthmatics and individuals with cardiovascular disease or chronic lung disease, as well as children and the elderly.

Sulphur dioxide acts as a precursor to sulphuric acid, which can kill aquatic organisms, damage habitat and erode buildings. Sulphur is the major component of increased acidification of the environment. Atmospheric sulphur is not usually absorbed by vegetation, but passes through to the soil in the form of sulphate. The deposition of sulphur may be dry (in the form of gases and particles), wet (in rain or snow), or in the form of condensation (as fog and cloud droplets).

(c) Linkages to Other Indicators: In addition to annual sulphur oxide emissions and the percentage change in emissions, emission intensity expressed as quantities emitted per unit of GDP, per capita and per unit of gross consumption of energy should be presented in order to assess sustainability. The indicators are therefore closely linked to GDP per capita, transport fuel consumption per capita, expenditure on air pollution abatement, and annual energy consumption per capita. High sulphur dioxide emissions per unit of GDP are, to some extent characteristic of countries undergoing rapid economic and industrial development or which have high industrial output in relation to population. High emissions per unit GDP may also reflect a lack of pollution control for sulphur dioxides and/or reliance on high-sulphur coal.

(d) Targets: For international targets, see section 3e below. Some countries have set national targets that are tighter than those of the international agreements. Few have met these national targets.

(e) International Conventions and Agreements: Within the framework of the Convention on Long-Range Transboundary Air Pollution (Geneva, 1979), the Helsinki Protocol to reduce sulphur emissions by 30 percent from 1980 levels by 1993 was signed in 1985 and entered into force in 1987. Within the framework of the same convention, the Oslo Protocol on sulphur emission ceilings and percentage emission reductions was signed in 1994.

4. Methodological Description and Underlying Definitions

In some rare cases emissions are known by direct measurements in stacks or by material balances. Generally sulphur oxide emissions are calculated with the help of emission factors that reflect the presence of sulphur compounds in different types of fuels and other products:

Emission = (Emission factor) x (Activity level)

Emission factors for stationary sources should be disaggregated by fuels, facilities or economic sectors. They should include power stations (gas, oil and coal), industrial processes (pollutants emitted in manufacturing products from raw materials), non-industrial fuel combustion, and other stationary sources (waste treatment and disposal, sewage treatment, agricultural activities and coal refuse burning). Emission factors for mobile sources should be disaggregated by fuels and types of vehicles. They should cover road traffic (passenger cars, light and heavy duty trucks, buses and coaches and motorcycles) and other mobile sources (navigation, railways, air traffic and agricultural equipment).

National emission factors should be used whenever available. If they are not readily available, or if the aim is to achieve a greater degree of international comparability, regionally specific or fuel specific emission factors can be used. Data derived this way, however, are likely to differ from official estimates. Differences still exist in countries' emission factors, estimation methods and definitions. Estimations of previous years are typically subject to revision as estimation methods become better. These underlying differences should, therefore, be kept in mind when interpreting the data.

Since the objective of the set of indicators is to describe the impact of human activity on environment, emissions from natural sources (such as forest fires and volcanic eruptions) should be excluded.

In recent years, considerable effort has been made to standardize or harmonize the calculation of national emission inventories for sulphur oxides in order to improve the comparability of national estimates. Work to standardize sampling and analytical methods for air pollution has been completed by the International Organization for Standardization, World Meteorological Organization (WMO), World Health Organization (WHO), the Economic Commission for Europe (UN ECE), Organisation for Economic Co-operation and Development (OECD), and the European Monitoring and Evaluation Programme (EMEP). The EMEP Task Force on Emission Inventories has developed a set of agreed technical guidelines for the calculation and reporting of national sulphur dioxide emissions. Under the terms of the Protocols to the UN ECE Convention on Long-Range Transboundary Air Pollution, signatory nations are required to submit data on national emissions to EMEP under these guidelines.

Purchasing power parities (PPPs) should be used instead of exchange rates when relating the emissions to GDP, as the objective of comparing levels of economic activity is to reflect underlying volumes and physical processes as closely as possible. In order to assess sustainability, it is important to study the trends in emissions over a longer time period (15 or 20 years). PPPs are defined as the ratio between the amount of national currency and the amount of a reference currency needed to buy the same bundle of consumption goods in the two countries. Typically, PPPs are different from exchange rates as the latter reflects not only the relative prices of consumption goods but a host of other factors, including international movements of capital, interest rate differentials and government interventions. As a consequence, exchange rates exhibit much greater variations over time than PPPs.

5. Assessment of the Availability of Data from International and National Sources

Presently, the main challenge concerning data on sulphur oxide emissions is to increase the frequency at which the data is collected, processed and updated at the national level. Annual changes in emissions cannot be calculated unless annual data is available. In a number of countries the current practice still is to publish emission inventories at five year intervals.

6. Agencies Involved in the Development of the Indicator

The lead agency for the development of this indicator is the Organisation for Economic Co-operation and Development (OECD). The contact point is Head, State of the Environment Division, Environment Directorate, OECD; fax no. (33 1) 45 24 78 76.

7. Further Information

US Environmental Protection Agency (EPA). National Air Quality Trends and Emissions Trends Report, 1993. EPA 454/R-94-026, 1994.

OECD. Environmental Data Compendium 1995. OECD, Paris, 1995.

OECD. Environmental Indicators: OECD Core Set. OECD, Paris, 1994.

United Nations Environment Programme (UNEP). Environmental Data Report 1993-1994. Basil Blackwell: Oxford, 1993.

Related work is being carried out by EMEP, UNEP, UN ECE, The World Bank, UN Commission on Sustainable Development, Eurostat, and the European Environment Agency.

1. Indicator

(a) Name: Emissions of nitrogen oxides.
(b) Brief Definition: National anthropogenic emissions of nitrogen oxides (NOx) expressed as amounts of nitrogen dioxide (NO2).
(c) Unit of Measurement: Tonnes or 1000 tonnes; % change in emissions over time (for example, % change in emissions between 1980 and 1995). Proposed denominator: per capita, per unit of Gross Domestic Product (GDP), per unit of gross energy consumption.

2. Placement in the Framework

(a) Agenda 21: Chapter 9: Protection of the Atmosphere.
(b) Type of Indicator: Driving Force.

3. Significance (Policy Relevance)

(a) Purpose: The indicator is used to evaluate the environmental performance of national policies and to describe the environmental pressure in relation to air emission abatement.

(b) Relevance to Sustainable/Unsustainable Development: Anthropogenic nitrogen oxide emissions are influenced by a country's industrial structure and energy consumption, which in turn is affected by both energy intensity and efficiency. The emissions are also influenced by the country's standard of pollution abatement and control, and the use of clean production technology. They give an indication of human impact on environment. Countries' efforts to abate nitrogen oxide emissions are reflected in national policies and international commitments. Concrete actions include structural changes in energy demand (energy savings and fuel substitution) as well as pollution control policies and technical measures (for example, the installation of industrial denitrification facilities, the use of catalytic converters on cars). The indicator can be used, therefore, to evaluate the environmental performance of national policies and to describe the environmental pressure in relation to production and consumption.

Together with sulphur compounds, nitrogen compounds are the source of environmental acidification. Anthropogenic nitrogen is predominantly emitted as nitrogen oxides by transport sources, as well as by other energy uses and industrial processes. Airborne emissions of nitrogen oxides contribute to local pollution as well as to large scale pollution through long distance transport in the atmosphere. Another source of nitrogen is nitrogenous fertilisers when used in excessive quantities in agriculture.

Nitrogen oxides are associated with both respiratory morbidity and mortality in humans. Nitrogen dioxide can irritate the lungs and lower the resistance to respiratory infections. The effects of short-term exposure are still unclear, but continued or frequent exposure to concentrations higher than those normally found in the ambient air may cause increased incidence of acute respiratory disease.

In the presence of sunlight, nitrogen oxides react with volatile organic compounds (VOCs) to form tropospheric ozone and other oxidizing chemicals; forms of oxygen that are toxic to living things, including human beings. Nitrogen oxides are also a precursor of nitric acid in rainwater, and they reinforce the deleterious effects of sulphur dioxide on artefacts, aquatic organisms, agriculture and habitat. Atmospheric deposition of nitrogen oxides can contribute to eutrophication. In some areas, nitrogen oxides are precursors to particulate matter concentrations. The deposition of nitrogen may be dry (in the form of gases and particles), wet (in rain or snow) or in the form of condensation (as fog and cloud droplets).

(c) Linkages to Other Indicators: In addition to annual nitrogen oxide emissions and their percentage change, emission intensity expressed as quantities emitted per unit of GDP, per capita and per unit of gross consumption of energy should be presented in order to assess sustainability. The indicators are therefore closely linked to GDP per capita, transport fuel consumption per capita, expenditure on air pollution abatement, and annual energy consumption per capita.

(d) Targets: See section 3e below.

(e) International Conventions and Agreements: Within the framework of the Convention on Long Range Transboundary Air Pollution (Geneva, 1979), a protocol to reduce nitrogen emissions to their 1987 level by 1995 (Sofia, 1988) entered into force in 1991.

4. Methodological Description and Underlying Definitions

In some rare cases emissions are known by direct measurements in stacks or by balance of material. Generally nitrogen oxide emissions are calculated with the help of emission factors that reflect the presence of nitrogen compounds in different types of fuels and other products:

Emission = (Emission factor) x (Activity level)

Emission factors for stationary sources should be disaggregated by fuels, facilities or economic sectors. They should include power stations (gas, oil and coal), industrial processes (pollutants emitted in manufacturing products from raw materials), non-industrial fuel combustion and other stationary sources (waste treatment and disposal, sewage treatment, agricultural activities and coal refuse burning). Emission factors for mobile sources should be disaggregated by fuels and types of vehicles. They should cover road traffic (passenger cars, light and heavy duty trucks, buses and coaches and motorcycles) and other mobile sources (navigation, railways, air traffic and agricultural equipment).

National emission factors should be used whenever available. If they are not readily available, or if the aim is to achieve a greater degree of international comparability, regionally specific or fuel specific emission factors can be used. Data derived this way, however, are likely to differ from official estimates. Differences still exist in countries' emission factors, estimation methods and definitions. Estimations of previous years are typically subject to revision as estimation methods become better. These underlying differences should, therefore, be kept in mind when interpreting the data.

Since the objective of the set of indicators is to describe the impact of human activity on environment, emissions from natural sources (such as lightning) should be excluded.

In recent years, considerable effort has been made to standardize or harmonize the calculation of national emission inventories for nitrogen oxides in order to improve the comparability of national estimates. Work to standardize sampling and analytical methods for air pollution has been completed by the International Organization for Standardization, World Meteorological Organization (WMO), World Health Organization (WHO), the Economic Commission for Europe (UN ECE), Organisation for Economic Co-operation and Development (OECD), and the European Monitoring and Evaluation Programme (EMEP). The EMEP Task Force on Emission Inventories has developed a set of agreed technical guidelines for the calculation and reporting of national nitrogen oxide emissions. Under the terms of the Protocols to the UN ECE Convention on Long-Range Transboundary Air Pollution, signatory nations are required to submit data on national emissions to EMEP under these guidelines.

Purchasing power parities (PPPs) should be used instead of exchange rates when relating the emissions to GDP, as the objective of comparing levels of economic activity such as GDP is to reflect underlying volumes and physical processes as closely as possible. In order to assess sustainability, it is important to study the trends in emissions over a longer time period (15 or 20 years). PPPs are defined as the ratio between the amount of national currency and the amount of a reference currency needed to buy the same bundle of consumption goods in the two countries. Typically, PPPs are different from exchange rates as the latter reflects not only the relative prices of consumption goods but a host of other factors, including international movements of capital, interest rate differentials and government interventions. As a consequence, exchange rates exhibit much greater variations over time than PPPs.

5. Assessment of the Availability of Data from International and National Sources

Presently, the main challenge concerning data on nitrogen oxide emissions is to increase the frequency at which the data is collected, processed and updated at the national level. Annual changes in emissions cannot be calculated unless annual data is available. In a number of countries the current practice still is to publish emission inventories at five year intervals.

6. Agencies Involved in the Development of the Indicator

The lead agency for the development of this indicator is the Organisation for Economic Co-operation and Development (OECD). The contact point is Head, State of the Environment Division, Environment Directorate, OECD; fax no. (33 1) 45 24 78 76.

7. Further Information

US Environmental Protection Agency (EPA). National Air Quality Trends and Emissions Trends Report, 1993. EPA 454/R-94-026, 1994.

OECD. Environmental Data Compendium 1995. OECD, Paris, 1995.

OECD. Environmental Indicators: OECD Core Set. OECD, Paris, 1994.

United Nations Environment Programme (UNEP). Environmental Data Report 1993-1994. Basil Blackwell: Oxford, 1993.

Related work is being carried out by EMEP, UNEP, UN ECE, The World Bank, UN Commission on Sustainable Development, Eurostat, and the European Environment Agency.

1. Indicator

(a) Name: Consumption of Ozone Depleting Substances (ODS).
(b) Brief Definition: This indicator will show the amounts of Ozone Depleting Substances being eliminated as a result of the Montreal Protocol.
(c) Unit of Measurement: Weighted tonnes of ODS.

2. Placement in the Framework

(a) Agenda 21: Chapter 9: Protection of the Atmosphere.
(b) Type of Indicator: Driving Force.

3. Significance (Policy Relevance)

(a) Purpose: This indicator signifies the commitment of the countries which have ratified the Montreal Protocol to the phaseout of ODS.

(b) Relevance to Sustainable/Unsustainable Development: The phaseout of ODS, and their substitution by less harmful substances, will lead to the recovery of the ozone layer and the use of more sustainable products. Stratospheric ozone absorbs most of the biologically damaging ultraviolet radiation (UV-B). Without the filtering action of the ozone layer more UV-B radiation can penetrate the atmosphere to have profound effects on human health, animals, plants, microorganisms, marine life, materials, biogeochemical cycles, and air quality.

(c) Linkages to Other Indicators: This indicator has links to other environmental and institutional indicators, such as number of chemicals banned or restricted and ratification of international agreements. It has significant implications to human health and natural resources.

(d) Targets: The target under the agreements listed in 3e below is the complete phaseout of ODS.

(e) International Conventions and Agreements: The Vienna Convention for the Protection of the Ozone Layer and its Montreal Protocol on Substances that Deplete the Ozone Layer.

4. Methodological Description and Underlying Definitions

(a) Underlying Definitions and Concepts: Ozone Depleting Substance means any organic substance containing chlorine or bromine, which destroys the stratospheric ozone layer. Production means the amount of listed, controlled substances produced; minus the amount destroyed by technologies to be approved by the Parties to the Montreal Protocol, and minus the amount entirely used as feedstock in the manufacture of other chemicals. The amount recycled and reused is not to be considered as "production". Consumption is the sum of production plus imports minus exports of controlled substances. Weighted tonnes of ozone depleting substances means the amount of ODS multiplied by their ozone depleting potential. Ozone depleting potential is a relative index of the ability of a substance to cause ozone depletion.

The reference level of 1 is assigned as an index to CFC-11 and CFC-12. If a product has an ozone depleting potential of 0.5, a given weight of the product in the atmosphere would, in time, deplete half the ozone that the same weight of CFC-11 or CFC-12 would deplete. Ozone-depletion potentials are calculated from mathematical models which take into account factors such as the stability of the product, the rate of diffusion, the quantity of depleting atoms per molecule, and the effect of ultraviolet light and other radiation on the molecules.

(b) Measurement Methods: Weighted Tonnes of ODS for production are the sum of national annual production (in tonnes) of each controlled substance (as reported to the Ozone Secretariat in accordance with Article 7 of the Montreal Protocol) multiplied by the ozone depleting potential of that substance (as listed in Annexes A, B, C and E of the Handbook of the Montreal Protocol on Substances that Deplete the Ozone Layer, 1993).

Weighted Tonnes of Ozone Depleting Substances for consumption are obtained through a similar calculation using national annual consumption values (in tonnes).

(c) The Indicator in the DSR Framework: The production and consumption of ODS represent a Driving Force indicator in the DSR Framework.

(d) Limitations of the Indicator: Availability and accuracy of data and timely reporting will determine the country's ability to use the indicator. The indicator by itself does not reveal much about current trends in the deterioration of the ozone layer because of delays in ecosystem response.

(e) Alternative Definitions: An alternative indicator could focus on the phaseout of ODS.

5. Assessment of the Availability of Data from International and National Sources

(a) Data Needed to Compile the Indicator: Data on production, imports and exports of controlled substances by the Parties to the Montreal Protocol.

(b) Data Availability: The data are available for most countries, on a national level, on a regular annual basis, as part of their reporting obligations to the Montreal Protocol.

(c) Data Sources: Data are available from the Ozone Secretariat and the national government ministry responsible for reporting to the Montreal Protocol.

6. Agencies Involved in the Development of the Indicator

(a) Lead Agency: The lead agency is the United Nations Environment Programme (UNEP). The contact point is the Director, Environmental ASSessment Programme, UNEP; fax no. (254 2) 62 42 74.

(b) Other Organizations: Other organizations interested in the further development of this indicator would include: the Technology and Economic Assessment Panel to the Montreal Protocol, the Parties to the Montreal Protocol, the Organisation for Economic Co-operation and Development (OECD), and members associated with the Alternative Fluorocarbon Environmental Acceptability Study (AFEAS).

7. Further Information

(a) Further Reading:

Ozone Secretariat. Handbook for the Montreal Protocol on Substances that Deplete the Ozone Layer. 1993.

Montreal Protocol Technology and Economic Assessment Panel Reports.

Reporting of Data by the Parties to the Montreal Protocol on Substances that Deplete the Ozone Layer.

Solomon and Albritton. Time-dependent Ozone Depleting Potentials for Short and Long Term Forecasts. Nature, Vol. 356, 7/5/92.

Environment Canada. Environmental Indicator Bulletin for Stratospheric Ozone. State of the Environment Reporting, 1995.

United Nations Environment Programme. Ad-hoc Technical Advisory Committee on ODS Destruction Technologies. 1992.

(b) Other Contact Points:

Coordinator, Secretariat for the Vienna Convention or the Protection of the Ozone Layer; fax. no. (254 2) 226886.

Chief, Global Environment Coordination, The World Bank; fax no. (1 202) 522 3256.

United Nations Industrial and Development Organization (UNIDO); fax no. (43 1) 211 232156.

Principal Technical Adviser, Environment & Natural Resources Group, BPPE, United Nations Development Programme (UNDP); fax no. (1 212) 906 6947.

Director, UNEP Industry & Environment Office (UNEP IE/PAC); fax no. (33 1) 4437 1474.

Chief Officer, Multilateral Fund for the Implementation of the Montreal Protocol; fax no. (1 514) 282 0068.

AFEAS Project Administrator, Alternative Fluorocarbon Environmental Acceptability Study (AFEAS); phone no. (1 202) 789 1201.

Environment Directorate, OECD; fax no. (33 1) 45 24 78 76.

1. Indicator

(a) Name: Ambient concentrations of pollutants in urban areas.
(b) Brief Definition: Ambient air pollution concentrations of ozone, carbon monoxide, suspended particulate matter, sulphur dioxide, nitrogen dioxide, and nitrogen monoxide.
(c) Unit of Measurement: fg/m3 or ppb for all pollutants except carbon monoxide which is measured in mg/m3 or ppm.

2. Placement in the Framework

(a) Agenda 21: Chapter 9: Protection of the Atmosphere.
(b) Type of Indicator: State.

3. Significance (Policy Relevance)

(a) Purpose: The purpose of these indicators is to measure the exposure of people to various air pollutants.

(b) Relevance to Sustainable/Unsustainable Development: An increasing percentage of the world's population lives in urban areas. The majority of pollution sources tend to be found in or close to urban areas. As a result, the greatest potential for human exposure to adverse environmental conditions and subsequent health problems occurs in urban areas. Improving air quality is a significant aspect of promoting sustainable human settlements.

Knowledge of air pollutant concentrations is needed to define areas of non attainment of air quality standards or guidelines, and to determine appropriate control measures on pollution sources. It is important to recognize that synergistic effects among these pollutants may increase the potential for adverse health effects.

(c) Linkages to Other Indicators: This indicator is closely linked to others which relate to causes, effects, and societal responses. These include, for example, the indicators on population growth rate, rate of growth of urban population, percent of population in urban areas, annual energy consumption per capita, emissions of sulphur oxides and nitrogen oxides, life expectancy at birth, total national health care as a percent of Gross National Product, share of consumption of renewable energy resources, environmental protection expenditures as a percent of Gross Domestic Product, and expenditure on air pollution abatement.

(d) Targets: World Health Organization (WHO) air quality guidelines exist for all the pollutants of this indicator, except nitrogen monoxide. Many countries have established their own air quality standards for many of these pollutants.

(e) International Conventions and Agreements: Not available.

4. Methodological Description and Underlying Definitions

(a) Underlying Definitions and Concepts: Air pollution monitoring is performed by representative random sampling and chemical analysis of air samples and comparison of statistical local parameters (such as arithmetic or geometric means, percentiles) with air quality standards or guidelines. Air samples may include samples of outdoor and/or indoor air.

(b) Measurement Methods:

i) Ozone:

Passive Samplers

Active Samplers

Automatic Samplers: Chemiluminiscence, UV-Absorption.

ii) Carbon monoxide:

Passive Samplers

 Active Samplers

Automatic Samplers: Non-dispersive infrared absorption, gas filter correlation method.

iii) Suspended particulate matter: 

Active Samplers

Automatic Samplers: Beta Ray Absorption.

iv) Sulphur dioxide: 

Passive Samplers

Active Samplers

Automatic Samplers: Conductometry, UV fluorescence.

v) Nitrogen dioxide: 

Passive Samplers