SI-MO – Sustainability Indicators – Malta Observatory
Report on Air Quality Sustainability Indicators
First Draft
Adrian Mallia
23 July 2001
SI-MO – Sustainability Indicators – Malta Observatory
Report on Air Quality Sustainability Indicators
First Draft
23 July 2001
Adrian Mallia
B.Sc M.Sc CBiol MIBiol MIEEM
Background
In November 2000, the OECD, through the University of Athens entered into a
contract with the Foundation for International Studies of the University of Malta, to
undertake a research programme entitled MED-ERMIS – MALTA. MED-ERMIS
(Mediterranean Environmental Reporting Monitoring and Information System) aims
to increase the capacity for observing environmental data and to set up a system for
monitoring and reporting sustainability indicators.
For this purpose, SI-MO (Sustainability indicators – Malta Observatory) was set up
and started functioning in February 2001.
In April 2001, the author was engaged to research the applicability of air quality
sustainability indicators to Malta. This report gives an overview of the concept of
sustainability indicators, reviews the use of such indicators by a number of
international organisations and individual countries and proposes air quality indicators
for Malta. These indicators are divided into two-tiers, mainly depending on the
availability of data or ease of computation.
Introduction
Indicators are essentially parameters, or values derived from such parameters, which
provide information about a phenomenon, environment or area but whose significance
goes beyond that directly associated with the parameter value (OECD, 1993).
Indicators have a specific meaning and a specific purpose so that they normally
possess two distinct functions:
a) they facilitate analysis of the big picture through a rough and ready collection
of information involving a reduced number of measurements and parameters
in a way that would not be possible for more detailed assessment of the
“exact” situation; and
b) they aid in the communication of the results to the users and the general public
by presenting normally complex situations in a succinct and simplified
manner.
Hence, indicators are largely approximations of the “real” picture and therefore may
not always meet the strict scientific demands to demonstrate causal chains. Therefore
they should at best be considered as an expression of the “best available knowledge”
on the subject.
Also, since indicators are used for widely varying purposes, it is important that they
be based on well-defined criteria. One such set of criteria is that established by the
Organisation for Economic Co-operation and Development (OECD)1 which include:
a)
b)
c)
policy relevance;
analytical soundness; and
measurability.
(OECD, 1993)
Although indicators have been in use for several years, most of the earlier applications
related to economic data. Only after the United Nations Convention on Environment
and Development (Rio Convention, 1992) was a major emphasis laid on the use of
environmental indicators in policy formulation and decision-making. Since then,
environmental indicators, and later sustainability indicators, have been developed by a
number of international organisations such as the OECD, the Mediterranean Action
Plan/BluePlan, the EU and the World Bank.
In the last decade or so, the popularity of environmental indicators has also increased
due to their applicability to other forms of environmental analysis, such as State of the
Environment Reports and Environmental Impact Assessment. Although possibly the
most attractive aspect of environmental indicators is their use in the assessment of
performance, whether of a project, of industry or of a whole nation. With the advent
of Strategic Environmental Assessment, especially with the upcoming EU directive
on the subject, and the recent decisions by the EU Council of Ministers meeting in
Göteborg wherein it was decided that the ecological dimension in the strategy for
sustainable development must be given the same prominence as social and economic
considerations in policy formulation, popularity and applicability of such indicators is
bound to increase.
What are sustainability indicators?
Sustainability indicators constitute a practical tool that can be used to help
communities develop in more sustainable directions. While economic indicators are a
familiar source of information on the economic performance of a country, however,
these indicators are inadequate at describing progress in social and environmental
directions. Sustainability indicators attempt to fill this information gap.
Sustainability indicators have three central functions:
a) to simplify the main concepts related to sustainable development;
1
See Table A – Criteria for Indicator Selection (OECD, 1993) attached as Appendix 1
b) to quantify and measure aspects of sustainable development; and
c) to communicate them to the public and policy makers
(Planning Authority, 1997)
Through these central functions, sustainability indicators help policy makers and the
public monitor progress in the country’s sustainable development path, while
inspiring people to take individual action and instigating change towards more
sustainable directions (Planning Authority, 1997).
Indicators in current use
As mentioned above, different types of indicators exist or have been proposed by
different organisations for different needs. Among the more widely used indicators
are those developed by the OECD, the Mediterranean Action Plan/BluePlan, the EU
and the World Bank. The following is a brief overview of the more popular sets of
indicators.
Organisation for Economic Co-operation and Development (OECD)
Users of indicators often have widely differing needs so that it is common for
indicators to be tailor-made for specific needs and to be developed and organized
around specific frameworks established for a specific purpose. These frameworks are
not necessarily governed by a unique set of criteria and they can also change as newer
information on the functioning of the environment becomes available and society’s
values evolve. In this context, the OECD developed the Pressure-State-Response
(PSR) framework (OECD, 2001).
The PSR framework (Figures 1 & 2) is based on a concept of causality: human
activities (transport, agriculture, energy generation, development) exert pressures on
the environment (air, water, land, ecosystems) and change its quality and the quantity
of natural resources (the so-called "state" box). Society responds to these changes
through environmental, general economic and sectoral policies (the "societal
response"). The latter form a feedback loop to pressures through human activities
(OECD, 1993). This framework is based on three sets of indicators – Indicators of
Environmental Pressures, Indicators of Environmental Conditions and Indicators of
Societal Responses.
In a wider sense, these steps form part of an environmental (policy) cycle, which
includes problem perception, policy formulation, monitoring and policy evaluation.
Following from the PSR Framework, the OECD established a “Core Set of
Environmental Indicators” (OECD, 1994). These are a commonly agreed upon set of
indicators for OECD countries and for international use. They are published regularly
and cover issues that reflect the major environmental concerns in OECD countries.
The publication incorporates major indicators derived from sectoral sets as well as
from environmental accounting, e.g. intensity of water use or of forest use (OECD,
2001).
TO ADD FIGURES 1 AND 2
The purposes of these indicators, as established by the OECD, are:




to keep track of environmental progress;
to ensure integration of environmental concerns into sectoral policies (e.g.
transport, energy and agriculture);
to ensure integration of environmental concerns into economic policies; and
to use indicators to measure environmental performance and to help determine
whether countries are on track towards sustainable development.
(OECD, 1998)
Blue Plan/Mediterranean Action Plan (MAP)
Another widely used set of indicators are those developed by the Mediterranean
Commission on Sustainable Development (MCSD), created in 1996, and by the Blue
Plan, one of the regional activity centres of the Mediterranean Action Plan (MAP) of
the United Nations Environment Programme (UNEP). The indicators, known as
Indicators for Sustainable Development (ISD) were the first step towards the
establishment of a Mediterranean evaluation system which aimed to build upon the
environment and development theme (Plan Bleu, 2000)
The result was a set of 130 ISD which were formally adopted by the Contracting
Parties of the Barcelona Convention in October 1999. Of the 130 indicators, the first
50 indicator sheets have since been published. These include 13 indicators on
“Population and Society”, 7 indicators on “Lands and Areas”, 23 indicators on
“Economic Activities and Sustainability”, 6 indicators on “Environment” and 1
indicator on “Exchanges and Cooperation in the Mediterranean”. These indicators too
are based on the Pressure-State-Response framework pioneered by the OECD.
The European Union
In 1997 the European Union, through EUROSTAT, embarked upon a project aimed at
establishing environmental pressure indicators for all 15 EU Member States. The
project, known as “Towards Environmental Pressure Indicators for the EU (TEPI)” is
a multi-annual project.
The objectives of the TEPI project are:
a) to calculate and present the six priority pressure indicators in each
environmental policy field for all 15 EU Member States, and
b) to present, where possible, the contributions of the economic sectors to the
environmental pressure.
(EUROSTAT, 2001)
The project reflects the efforts undertaken by the European Commission to provide
decision-makers and the general public with the information necessary for the design
and monitoring of an adequate environment policy for the European Union.
This was one of the main considerations emanating from the European Commission’s
Communication to the Council of Ministers and European Parliament titled:
"Directions for the EU on Environmental Indicators and Green National Accounting"
(COM (94) 670 final, 21.12.94) (EC, 1994).
The first edition of the TEPI report included 60 indicators. These were produced
from a number of sources, varying from existing EUROSTAT data to data available at
other international institutes or new data. This obviously resulted in varying accuracy
of the data and therefore the indicators are accompanied by a quality assessment
based on traffic light colours (“Good” – green; “Medium” – Orange; “Deficient” –
Red) for the following criteria:
A)
B)
C)
D)
Relevancy
Accuracy
Comparability over time
Comparability over space
(TEPI website, 2001)
Further work on the TEPI indicators resulted in a reduction of indicators to 48 when
the second edition was published. These give a comprehensive description of the
most important human activities that have a negative impact on the environment, such
as emissions of pollutants, waste production, land use and noise (Eurostat, 2001).
The World Bank
The World Bank also uses indicators. In this case, the indicators used are based on
social, economic and environmental parameters.
The latest publication by the World Bank on the subject is “World Development
Indicators (WDI) 2001”. This is the Bank’s annual compilation of data about
development and includes 800 indicators in 87 tables, organised in six different
sections. These are: world view, people, environment, economy, states and markets,
and global links. The tables cover 148 economies and 14 country groups—with basic
indicators for a further 59 economies (World Bank, 2001).
Apart from the above international organisations, individual countries have also
established a set of environmental or sustainability indicators for local, regional or
national use. These include Canada, the United Kingdom, certain states of the USA,
the Netherlands, Norway and, more recently, Finland. The vast majority of this
activity has taken place in the 1990s so that most of this work is pretty recent.
Air Quality as an indicator of sustainability
Clear and clean air is essential to protect human health and the environment. Good air
quality is a fundamental aspect of the quality of life and is an essential component of
sustainable development. So much so that several countries have identified urban air
quality as a major indicator for sustainability. Poor air quality can contribute to ill
health, resulting in elevated numbers of hospital admissions annually and in some
cases also deaths. Poor air quality also has environmental impacts, such as acid rain,
eutrophication2 of lakes, streams, rivers and bays and damage to vegetation, buildings,
monuments and fittings.
Emissions to the atmosphere, for example, from traffic and industrial activity, impact
air quality on both a local and national scale. It is now clear that emission of some
substances, for example, emissions of greenhouse gases (such as carbon dioxide and
methane) and ozone depleting chemicals also have international and global
environmental impacts. Emissions of sulphur dioxide (SO2) and oxides of nitrogen
(NOx) have contributed to the acidification of sensitive ecosystems in northern Europe
and elsewhere.
In the UK alone, it is estimated that air pollution brings about no less than 24,000
hospital admissions annually.
Air quality problems also have international overtones since air respects no national
political boundaries but is rather a “global commons”. Deterioration of the quality of
the air in one place can have impacts on localities downwind. In some cases,
solutions at one locality caused deterioration in the quality of the air in another.
Hence, air quality is an important environmental parameter that requires constant
monitoring and therefore the use of specific air quality indicators are essential in any
set of sustainability indicators.
In order to determine the state of the air in a particular country and therefore the
adverse environmental effects created as a result of air pollution, the quality of the air
must be measured and changes in it tracked over a period of time. However it is
impossible to monitor all potential air contaminants. Hence, a few “priority”
pollutants are selected that can give a representative picture of air quality. These can
be used as indicators.
Indicators in practice
All published sets of environmental or sustainability indicators include aspects of air
quality. These can be direct indicators on emission levels of specific pollutants,
composite indicators on, say, emissions of greenhouse gases or indirect indicators
having a bearing on or themselves influenced by air quality, such as indicators on
traffic density.
The following sections give an overview of the air quality related indicators used in
sets of indicators established by the OECD, the MAP/Blue Plan, the European Union,
the World Bank, the New Zealand Ministry for the Environment and the Scottish
Environment Protection Agency.
2
Eutrophication is the phenomenon whereby aquatic plants undergo rapid growth due to overnourishment resulting from excess nutrients in the water, normally a result of organic pollution.
OECD
The Core Set of Indicators established by the OECD includes a number of air quality
related indicators. These relate to issues such as Climate Change and Stratospheric
Ozone Depletion as well as acidification (indirectly) and urban environmental quality.
Slightly different indicators may be applicable in each case, although several of the
indicators are related or have similar or equivalent data sources.
The OECD also classifies the indicators according to whether they are first choice or
proxies for indicators that are less easily measurable.
All indicators are also
classified on the basis of availability (or the ease of data collection). Hence,
indicators are indicated as being either measurable in the short term (S), requiring
additional empirical work and data collection effort and therefore only measurable in
the medium-term (M) and those measurable in the long-term since they need
significant data development work (L).
TABLE 1 – Table showing Air Quality indicators used in the OECD Core Set of
Indicators
PRESSURE
STATE
RESPONSE
Indicators
of Indicators
of Indicators
of
social
environmental pressures
environmental conditions
responses
Climate
S
M/L
 Index
of M
 Atmospheric
 Energy
Change
greenhouse gas
concentrations
efficiency
S
emissions*
of greenhouse
 Energy
gases*
 CO2 emissions
intensity
 Global
mean S
 Economic and M
temperature*
fiscal
instruments
Ozone Layer  Index
S/M  CFC recovery M
of M
 Atmospheric
Depletion
apparent
concentrations
rate*
consumption of
of
ozone
ozone
depleting
depleting
substances*
M
substances*
 Ground-level
S/M
 Apparent
UV-B
consumption of
radiation*
CFCs
and
halons
Acidification
 Index
of M/L  Concentrations S
 % of car fleet S/M
acidifying
in
acid
equipped with
substances*
precipitation
catalytic
S
converters*
 Emissions of
NOx and SOx
 Capacity of SOx M/L
and
NOx
abatement
equipment
of
stationary
sources*
Issues
PRESSURE
Urban
Environmental
Quality
General
indicators, not
attributable to
specific issues





Urban
air
emissions:
SOx,
NOx,
VOC*
Traffic density
-- urban
-- national
Road traffic
volumes*
STATE
M/L


Population
exposure to:
-air
pollution*
RESPONSE
L
M
M
S
S

Economic,
fiscal
and
regulatory
instruments*
 Pollution
control
and
abatement
expenditures
M
S/M
Note: indicators marked with an (*) are “main” indicators.
Source: OECD, 1994
MAP/Blue Plan
The Blue Plan has, over the past years, developed a number of projects relating to
indicators in the Mediterranean region. Currently there are two kinds of projects
underway:
a) The Environmental Performance Indicators Project (EPI) - this aims at promoting
the use of environmental performance indicators as a means of assessment of policies
or projects in relationship to environmental goals in the 13 Mediterranean countries or
territories benefiting from the METAP programme. The project has focused on 4
topics (waste, air quality, water quality and water resources).
b) The Indicators for Sustainable Development Project (ISD) – this aims more
generally at developing indicators of progress towards sustainable development in the
20 Mediterranean-rim countries, the Contracting Parties to the Barcelona Convention.
These indicators are not only environmental but encompass also economic and social
development and future generations. This work has been undertaken through the
Mediterranean Commission on Sustainable Development and has been tested at
national level (Morocco, Slovenia and Tunisia) and local level (the Malta CAMP 3).
This activity made it possible to arrive at the recommendations adopted in November,
1999, in Malta by the Contracting Parties, especially including the adoption of a "joint
set" of 130 indicators for sustainable development in the Mediterranean.
In their proposed set of 130 indicators, MAP/Blue Plan have currently outlined two
air quality indicators. These relate to “Emissions of Greenhouse gases” and
“Consumption of Ozone Depleting Substances”.
3
The Coastal Area Management Programme for Malta is a project financed by the Priority Actions
Programme (PAP) of the United Nations Environment Programme (UNEP) and the Government of
Malta.
The indicator dealing with greenhouse gases is essentially an aggregate indicator of
the main man-made green house gas (GHG) emissions. These include carbon dioxide
(CO2), methane (CH4) and nitrous oxide (N20). These gases are those mainly
responsible for the greenhouse effect. This indicator can also be expressed as a
percentage of reduction in aggregated emissions since 1990. In this way, it offers an
immediate view of each country’s efforts to reach the targets established by the
Convention on Climate Change.
The indicator on consumption of ozone depleting substances is the sum of annually
consumed quantities of organic substances containing chlorine or bromine, which
substances deplete the stratospheric ozone layer. Consumption here is the sum of
production plus imports minus exports of controlled substances as defined by the
Montreal Protocol4 (UNEP, 2000). The indicator is expressed in tonnes of ozone
depleting substances weighted by their ozone depleting potential (ODP). This
indicator essentially aims to highlight the decrease in the consumption of ozone
depleting substances as envisaged in the timetables established by the contracting
parties of the Montreal Protocol. The phasing out of damaging substances and their
replacement by less reactive substances would bring about a recovery of the ozone
layer.
Other indicators having a bearing on air quality include the following:
a) Annual energy consumption per inhabitant
b) Number of passenger cars per 100 inhabitants5
c) Structure of transport by mode (i.e. road, rail and air)
The European Union
The first TEPI project of the European Union utilised a number of indicators related
to Air Pollution and Climate Change. These are:
Code
Indicator
Definition
Air Pollution
AP1
AP2
AP3
AP4
AP5
AP6
Emissions of nitrogen oxides (NOx)
Emissions of non-methane volatile organic
compounds (NMVOCs)
Emissions of sulphur dioxide (SO2)
Emissions of particles
Consumption of petrol and diesel oil by road
vehicles
Primary energy consumption
Kt NOx per year
Kt NMVOCs per year
Kt SO2 per year
Kt of particles per year
Kt of petrol and diesel oil per year
Mtoe per year
Climate Change
4
The Montreal Protocol on Substances that Deplete the Ozone Layer (1987)
This indicator can be connected to other indicators like traffic congestion in urban surroundings, and
gas and particle emissions into the atmosphere.
5
CC1
Emissions of carbon dioxide (CO2)
Tonnes CO2 per year
CC2
Emissions of methane (CH4)
Tonnes CH4 per year
CC3
Emissions of nitrous oxide (N2O)
Tonnes N20 per year
CC4
Emissions of Hydrofluorocarbons (HFCs)
Tonnes CO2 per year
CC5
Emissions of PerFluoroCarbons (PFCs)
CC6
Emissions of Sulphurhexafluoride (SF6)
Ozone Depletion
Tonnes total emissions CFC-11 per year
OD1
Emissions of bromofluorocarbons (halons)
OD2
Emissions of chlorofluorocarbons (CFCs)
Ditto
OD3
Emissions of hydrochlorofluorocarbons (HCFCs)
Ditto
OD4
Emissions of nitrogen oxides (NOx) by aircraft
Tonnes NOx per year
OD5
Emissions of chlorinated carbons
Tonnes total emissions CFC-11 per year
OD6
Emissions of industrially produced methyl
bromide
Ditto
Source: TEPI website, 2001
Data for the compilation of these indicators was obtained from the CORINAIR
Inventories of the European Environment Agency (EEA).
In the second edition, the number of indicators was brought down to 48 from 60, with
some of the indicators being amalgamated into one.
The World Bank
In the case of air quality (referred to as “air pollution”), the World Bank indicators are
restricted to a few of the more important indicators. These are:
Carbon dioxide damage as share of GDP
Carbon dioxide emissions per capita
Carbon dioxide emissions per PPP dollar GDP
Total Carbon dioxide emissions
Nitrogen dioxide, selected cities
Sulfur dioxide, selected cities
Suspended particulates, selected cities
Source: WDI2001, World Bank website, 2001b
These are an improvement over the WDI2000 indicators, which only included the
following indicators:
Total suspended particulates
Sulfur dioxide
Nitrogen dioxide
micrograms per cubic meter
micrograms per cubic meter
micrograms per cubic meter
Source: WDI2000, World Bank website, 2001b
Nonetheless, this list of indicators should be increased further to at least include
indicators on other important pollutants, such as carbon monoxide and ozone.
New Zealand
The New Zealand Ministry for the Environment established an Environmental
Performance Indicators Programme in the mid 1990s. This aimed to develop and
implement a set of environmental indicators for the country. One such set of
indicators was that relating to air quality.
Air indicators provide key information with which to measure and report on:



the state of New Zealand’s air quality, by comparing monitoring results to air
quality guidelines and categories
changes in air quality over time (e.g. changes in lead levels in air with the
progressive introduction of unleaded petrol)
the difference between air quality in urban areas and natural background areas
(New Zealand Ministry for the Environment, 2001)
In New Zealand, regional councils and unitary authorities are responsible for
managing discharges into the air and for ensuring that outdoor air is clean and healthy
to breathe. To do this they develop regional air quality plans under the Resource
Management Act (1991). These plans contain policies and rules tailored to managing
the particular causes of any air quality problems in the region.
The ministry also runs an air quality management programme that aims to develop
national policies and tools that maintain air quality where it is clean and enhance the
air where it has been polluted (New Zealand Ministry for the Environment, 2001).
The New Zealand indicators have been developed in two stages. In the case of air
quality, Stage 1 indicators included the following:
TABLE 2 - Stage 1 Air Indicators
Indicator
6
Why it is important?
Ambient Air Quality Guideline
(1994)6
Ambient Air Quality Guidelines were issued in 1994 by the New Zealand Ministry for the
Environment. A table describing the Air Quality Guidelines Categories used is reproduced in
Appendix 2.
Particles less than 10 Particles cause adverse effects 120 µg/m3 (24 hour average)**
microns in diameter on human health and degraded
(PM10)
visibility such as regional haze
Carbon monoxide CO
CO causes adverse effects on 10 mg/m3 (8 hour average)
human health
Nitrogen dioxide NO2
NO2 causes adverse effects on 300 µg/m3 (one hour average)**
human health and causes the
brown colouration of hazes and
smogs
Sulphur Dioxide SO2
SO2 causes adverse effects on 125 µg/m3 (24 hour average)
human health and on vegetation
Ozone O3
Ground level ozone formed by 100 µg/m3 (8 hour average)
reactions of other pollutants in
the air can adversely affect
human health and vegetation
* The Ministry for the Environment is currently reviewing the Ambient Air Quality Guidelines to
bring them up to date with the latest overseas research
** For regional air quality management, some regional councils have set guidelines or targets
that are stricter than the Ministry’s Ambient Air Quality Guidelines
Stage 2 indicators were subsequently proposed as possible future development. These
are reproduced in Table 3 below:
TABLE 3 – Stage 2 Indicators - Proposed Indicators Requiring Further Development
Indicator
Why is it important?
Ambient Air Quality Guideline
Visibility
Good,
clear
visibility, Not yet determined
unaffected by human sources
of pollution, is an important
asset for New Zealand that
should be protected. Visibility
is one of the most commonly
used indicators of air quality.
Benzene
Long term inhalation of Not yet determined
benzene can cause adverse
effects on human health
Particles with a These smaller particles are Not yet determined
diameter less than believed to be the most
2.5 microns (PM2.5) important particles causing
adverse effects on human
health and visibility
Lichen
diversity/coverage
Lichens are very sensitive to Not yet determined
air pollution and they provide a
living, easy to see indicator of
the effects of air pollution
Each of the above indicators is supported by specific indicator details (see examples
in Appendix 3).
United Kingdom
The United Kingdom too has established air quality indicators. In 1996 a report
entitled “Indicators of Sustainable Development for the United Kingdom was
published. This dealt with the three pillars of sustainable development – social
progress, economic growth and environmental protection - and established a number
of indicators, including health, transport, energy and urban issues. The indicators are
divided into headline indicators (15), National Indicators (147), Regional Indicators
(9), and Local Indicators (29). Air quality indicators were included under Climate
Change, Ozone Layer Depletion, Air Quality, Tropospheric Ozone and Urban Issues.
Within the United Kingdom, further indicators were developed in Scotland. The
examples quoted below are those established by the Scottish Environment Protection
Agency (SEPA, 2001).
The air quality indicators used in Scotland are the following:
a)
b)
c)
d)
e)
f)
g)
h)
Sulphur dioxide
Benzene
1,3-Butadiene
Carbon Monoxide
Lead
Oxides of Nitrogen
Ozone
Particulates
As is usual, these pollutants have been chosen as indicators from among a host of
other pollutants in view of their toxicity, their widespread occurrence and/or history
of monitoring (and therefore availability of data). The Scottish Environmental
Indicators Strategy (SEPA, 2001), establishes an annual mean value for the pollutant
to be reached by a certain date (e.g. 31 December 2003). In some cases, other mean
values are given. The different values for the various indicators are reproduced in
Appendix 4.
Applicability in the local context
As with all indicators, those that should ultimately be used should have a sound
scientific basis and be representative of the issue being monitored. In the case of air
quality, indicators are normally based on a few representative pollutants, some of
which being aggregates for a suite of similar types of contaminants (e.g. particulates,
oxides of nitrogen, etc.).
It is also important that any data collected on which to base the indicator (or to take
action following the establishment of the indicator) is representative. In particular air
quality indicators must ensure that:
(i) the number of days above the Standard recorded at a site in each
year are representative of pollutant conditions at the sites; i.e., that on
days where Low Pollution is recorded at a site this was not due to the
absence of measurements for one or more key pollutants;
(ii) there are adequate days of data in each year for data provided from
each site to be considered representative of the year as a whole; and
(iii) there are adequate sites for these to be representative and a robust
trend produced.
Locally, two institutions – the Environment Protection Department and the University
of Malta, have systematically collected air quality data. The parameters collected by
the Atmospheric Research Station of the University of Malta are Ozone and, more
recently, Carbon Monoxide (University of Malta, 2001), whereas since 1999, the
Environment Protection Department has been undertaking a routine National Air
Monitoring Programme. This programme aims:



to provide a preliminary assessment of air quality based on scientific criteria;
to enable air pollution mapping in the Maltese Islands; and
to provide an initial basis for more comprehensive monitoring.
This programme involves monitoring of a number of key air pollution parameters,
amongst which are sulphur dioxide, nitrogen oxides, ozone, carbon monoxide and
particulate matter. This monitoring is carried out using automatic equipment mounted
on a mobile station7, which is periodically stationed at 31 different localities in the
Maltese Islands (EPD, 2001).
The results obtained from the monitoring is then compared with internationally
accepted air quality standards as reproduced in Table 4 below:
7
The Environment Protection Department has recently issued a call for tender for the supply for a
further mobile station. Apart from the parameters measured to date, the specifications include
measurements for BTX (Benzene, Toluene and Xylene).
TABLE 4 – Air Quality Standards used in Malta
AIR QUALITY STANDARDS
Parameter
Standard
Reference
SO2
L)imit V)alue
A)lert T)hreshold
44ppb (24hr average)
175ppb (hourly average over 3
consecutive hours)
EU Directive
99/30/EC
NO2
A)lert T)hreshold
213ppb (hourly average over 3
consecutive hours)
EU Directive
99/30/EC
O3
P)op. I)nfo.
T)hreshold
P)op. W)arn.
T)hreshold
90ppb (hourly average)
180ppb (hourly average)
EU Directive
92/72/EEC
CO
G)uideline V)alue
9ppm (8 hourly average)
WHO
PM10
L)imit V)alue
50µg/m3 (24 hour average)
EU Directive
99/30/EC
Parameter Description
SO2
Sulphur Dioxide
NO2
Nitrogen Dioxide
O3
Ozone
CO
Carbon Monoxide
PM10
Particulate Matter (less than 10µm)
Source: Environment Protection Department website, 2001
Examples of the type of air quality data available from the Environment Protection
Department is reproduced in Appendix 5.
From this information, and assuming that the National Air Monitoring Programme
(NAMP) is continued, one can safely say that enough robust data should be available
to measure air quality values and to monitor the performance of these indicators.
Hence, it would be logical to utilise the values provided by the NAMP and use these
as the indicators, basing the values on EU directive or WHO criteria as outlined in
Table 4 above. Apart from the above, the measurement of CO2 levels should be
actively considered.
Secondary level indicators could also be utilised if data is or becomes available.
These could include indicators such as:
Emissions
Emissions of CO2, SOx and NOx per capita
Emissions of CO2, SOx and NOx per unit of GDP
Economic measures/Incentives
Percentage of car fleet equipped with catalytic converters
Capacity of SOx and NOx abatement equipment at stationary sources
Expenditure for air pollution abatement
Amenity/Regulation
Traffic density
Exposure of population to air pollution
Reduction (-ve) / Increase (+ve) changes in area of green space as a percentage of
the total urban area/total urban population
Regulations on emissions for new cars
Percentage of days with good visibility
Indicator assessment & classification
The above first-level and second-level indicators were assessed on the basis of their
ease of computation and availability of data. The following table outlines the results:
TABLE 5 – Assessment of Air Quality Indicators and their applicability in the local
context
Indicator
Data
availability
Ease of
computation
Source of data
Computational
Improvements
FIRST LEVEL
SO2 concentration
NO2 concentration
O3 concentration
CO concentration
PM10 levels
CO2 concentrations






Easily computed
EPD
Easily computed
EPD
Easily computed
EPD, UoM
Easily computed
EPD, UoM
Easily computed
EPD
Impossible to
compute
N/A
Only through further
investment and
extension of
monitoring programme
Indicator
Data
availability
Ease of
computation
Source of data
Computational
Improvements
SECOND LEVEL
Emissions of CO2
per capita

Impossible to
compute
N/A
Emissions of SOx
per capita

Easily computed
EPD, NSO, PA
Emissions of NOx
per capita

Easily computed
EPD, NSO, PA
Emissions of CO2
per unit of GDP

Impossible to
compute
N/A
Emissions of SOx
per unit of GDP

Easily computed
EPD, NSO
Emissions of NOx
per unit of GDP

Easily computed
EPD, NSO
Percentage of car
fleet equipped with
catalytic converters
?
Somewhat
difficult to
compute
NSO (?)
Capacity of SOx and
NOx abatement
equipment at
stationary sources

Easily computed
EPD
Expenditure for air
pollution abatement
?
Somewhat
difficult to
compute
NSO (?)

?
Easily computed
PA
Somewhat
difficult to
compute
EPD, PA, NSO
May require data
interpolation from
different datasets and
organisations and
possibly establishment
of further monitoring
stations
?
Somewhat
difficult to
compute
PA
Additional data capture
to establish baseline
and trends
Traffic density
Exposure of
population to air
pollution
Reduction (-ve) /
Increase (+ve)
changes in area of
green space as a
percentage of the
total urban area/total
urban population
Indicator
Data
Ease of
Source of data
Only through further
investment and
extension of
monitoring programme
Only through further
investment and
extension of
monitoring programme
Collection of
information from a
number of entities and
industrial concerns
Computational
availability
computation
Regulations on
emissions for new
cars

Impossible to
compute (no
regulations to
date)
Percentage of days
with good visibility
?
Somewhat
difficult to
compute
Lichen
Diversity/Coverage
(in specific urban
localities)
?
Symbol


?
?
?
Improvements
Depends on new
regulations
Met Office
UoM ?
Depends on the quality
of existing data and the
exact definition of
“good visibility” in the
indicator
Requires a baseline
survey of lichens in the
Maltese Islands (unless
available) and a
systematic monitoring
programme based on
an agreed number of
monitoring locations
Meaning
Data readily available
Data not available
No information
Data possibly available
Data probably not available
CONCLUSIONS & RECOMMENDATIONS
Sustainability indicators have a number of inherently positive characteristics. These
include:
a) provision of detailed and up-to-date information on the state of the
environment in line with the recommendations of the Rio Declaration and the
Aarhus convention;
b) improving public awareness about environmental and sustainability issues,
which may lead to lifestyle changes;
c) provision of a tool for environmental and economic policy-making within a
sustainability framework;
This report has assessed the suitability of including air quality indicators in a
prospective list of sustainability indictors for the Maltese Islands and also identified
the potential list of indicators to be used in such a list.
It is the opinion of the author that the indicators so identified can be utilised locally
and that the data can be obtained with relative ease assuming that the current data
collection and monitoring exercise are sustained and adequately funded. A set of
second-tier air quality indicators can also be considered for future development.
It is also suggested that the University of Malta and the Environment Protection
Department collaborate further in their research and monitoring endeavours to
minimise duplication of work and to try to set up complimentary monitoring
structures or a more formal partnership.
REFERENCES
Blue Plan, 2001. Official website. Available online at http://www.planbleu.org
Environment Protection Department, 2001. Official website. Available online at
http://www.environment.gov.mt
European Communities, 1994. Directions for the European Union on Environmental
Indicators and Green National Accounting (COM(94)670 final).
European Environment Agency, 1996. CORINAIR 90 Emissions Data. European
Topic Centre on Air Emissions.
European Environment Agency, 2001.
http://eea.eu.int
Official website.
Available online at
EUROSTAT, 1999. Towards Environmental Pressure Indicators for the EU.
EUROSTAT,
2001.
Official
http://europa.eu.int/comm/eurostat/
website.
Available
online
at
New Zealand Ministry for the Environment, 2001. Official website. Available online
at http://www.mfe.govt.nz
OECD, 1993. OECD Core Set of Indicators for Environmental Performance Reviews.
A synthesis report by the Group on the State of the Environment. OECD
Environment Monographs No. 83. OCDE/GD(93)179. OECD, Paris; 39pp.
OECD, 1994. Environmental Indicators. OECD Core Set.
Economic Co-Operation and Development, Paris; 157 pp.
Organisation for
OECD, 1998. Towards Sustainable Development – Environmental Indicators.
Organisation for Economic Co-Operation and Development, Paris; 130 pp + 33 tables
+ 33 graphs.
Organisation for Economic Co-Operation and Development, 2001. Official website.
Available online at http://www.oecd.org
Plan Bleu, 2000. 130 Indicators for Sustainable Development in the Mediterranean
Region. Plan Bleu – Centre d’Activites Regionales, Mediterranean Action Plan,
UNEP, Valbonne, France; 50 sheets.
Planning Authority, 1997. Sustainability Indicators for Malta – A Proposal. Final
Draft report. Planning Authority, Floriana; 36 pp.
Scottish Environment Protection Agency (SEPA), 2001. Official website. Available
online at http://www.sepa.org.uk
TEPI, 2001. Official website. Available online at http://www.e-m-a-i-l.nu/tepi/
UNEP, 2000. The Montreal Protocol on Substances that Deplete the Ozone Layer as
adjusted and/or amended in London 1990, Copenhagen 1992, Vienna 1995, Montreal
1997, Beijing 1999. Ozone Secretariat, United Nations Environment Programme,
Kenya.
University of Malta,
http://www.um.edu.mt
2001.
Official
website.
Available
online
at
World Bank, 2000.
University Press.
World Development Indicators 2000.
New York: Oxford
World Bank, 2001a.
University Press.
World Development Indicators 2001.
New York: Oxford
World Bank, 2001b. Official website. Available online at http://www.worldbank.org
APPENDIX 1
Criteria for Selection of Indicators
Organisation for Economic Cooperation and Development
Table A. Criteria for Indicator Selection *
Policy relevance and utility for users
An environmental indicator should:
• provide a representative picture of environmental conditions, pressures on the environment
or society’s responses;
• be simple, easy to interpret and able to show trends over time;
• be responsive to changes in the environment and related human activities;
• provide a basis for international comparisons;
• be either national in scope or applicable to regional environmental issues of national
significance;
• have a threshold or reference value against which to compare it so that users are able to
assess the significance of the values associated with it.
Analytical soundness
An environmental indicator should:
• be theoretically well founded in technical and scientific terms;
• be based on international standards and international consensus about its validity;
• lend itself to being linked to economic models, forecasting and information systems.
Measurability
The data required to support the indicator should be:
• readily available or made available at a reasonable cost/benefit ratio;
• adequately documented and of known quality;
• updated at regular intervals in accordance with reliable procedures.
*These criteria describe the "ideal" indicator and not all of them will be met in practice.
Source: OECD Core Set of Indicators for Environmental Performance Reviews. A synthesis report by
the Group on the State of the Environment. OECD, 1993
APPENDIX 2
Ambient Air Quality Guidelines (1994) - Ministry for the
Environment, New Zealand.
Description of Air Quality Guidelines Categories
Category
Percent of Guideline
Comment
Excellent
Less than 10% of the Is of little concern, if maximum values
guideline
are less than a tenth of the guideline,
average values are likely to be much
less
Good
Between 10% and 33% of Peak measurements in this range are
the guideline
unlikely to impact air quality
Acceptable
Between 33% and 66% of A broad category, where maximum
the guideline
values might be of concern in some
sensitive locations but generally at a
level which does not warrant dramatic
action
Alert
Between 66% and 100% of A warning level, which can lead to
the guideline
exceedences if trends are not curbed
Action
More than 100% of the Exceedences of the guideline are a
guideline
cause for concern and warrant action if
they occur on a regular basis
Source: New Zealand Ministry for the Environment website, 2001
APPENDIX 3
New Zealand - Ministry for the Environment
Environmental Performance Indicators Programme
Air Quality Indicators
Particulate Matter
Particulate matter refers to numerous substances that exist in a solid or aerosol (suspended in gas)
state at ambient conditions. Particles range over several orders of magnitude in size, from over
100µm down to aggregations of molecules.
Smoke consists of the products of incomplete combustion, carbon, and organics. Depending on
the combustion source, it can contain both deposited particulate and finer matter in suspension and
therefore poses both a nuisance and a health effect.
Deposited particulate consists of the larger diameter portion of combustion process exhausts or
dusts naturally occurring in the environment. Generally it is larger than 20 µm in size and can
pose a nuisance from deposition on property and also has some potential health effects.
Suspended particulate consists of particles mostly smaller than 20 µm. The coarse fraction,
larger than 2.5 µm, originates from combustion and naturally occurring dusts and salt spray. The
fine fraction, smaller than 2.5 µm, is also produced naturally and from industrial processes and
can cause health effects as it falls within the respirable range.
Visibility-reducing particulate consists of the fine particles in the size range 0.1 to 2.0 µm.
These particles have the ability to scatter and absorb light, thereby impairing visibility. Although
particles smaller than 0.1 µm do not affect visibility directly, they are important because they can
react chemically and physically in the atmosphere to produce larger particles.
Since 1987 in the United States, the principal air quality indicator for adverse health effects from
particulates has been PM10, which represents the portion of the particulate matter which is smaller
than 10 µm in diameter. This has been adopted by New Zealand’s Ministry for the Environment,
as it indicates the fraction of the particles that can enter the upper respiratory tract.
Adverse Effects
Humans exposed to particulate in the air they breathe may experience some discomfort from
irritation by specific compounds as they are filtered by the nose and mouth. Particles larger that
10µm are removed at this stage. Smaller particles penetrate into the lungs where they may be
deposited and subsequently cleared.
Acute exposure to inhalable particulate can result in loss of lung function, onset of respiratory
symptoms, aggravation of existing respiratory conditions, and loss of capacity to resist infection.
These problems occur particularly in the sensitive populations of asthmatics, small children, and
the elderly.
Typical PM10 Concentrations
NZ Ambient Air Quality Guideline
120 µg/m3 for a 24 hour period
Typical New Zealand Urban Actual
25-35 µg/m3 for a 24 hour period
Typical New Zealand Rural Actual
2-10 µg/m3 for a 24 hour period
Typical New Zealand Peak
>500 µg/m3 for a 24 hour period
Source: New Zealand Ministry for the Environment, 2001
New Zealand - Ministry for the Environment
Environmental Performance Indicators Programme
Air Quality Indicators
Carbon Monoxide
Carbon Monoxide (CO) is a colourless, odourless gas that can be poisonous to humans. CO is a
trace constituent of the atmosphere, produced by both natural processes (such as volcanoes,
bushfires, and metabolism of organisms) and human activities (such as incomplete combustion of
fuels, milling, and foundries).
CO occurs both indoors and outdoors. Heating and cooking appliances that are fuelled by anything
other than electricity are sources of CO, but the most significant source is undoubtedly motor
transportation (from fossil fuel combustion). Places where transport emissions accumulate such as
traffic jams, tunnels, and car parks are locations of potentially significant exposure. Office
buildings and shops located along congested motorways or above or below car parks can also
accumulate CO.
Adverse Effects
CO is readily absorbed from the lungs into the bloodstream where it competes with oxygen for
attachment to haemoglobin (Hb). The presence of CO in the blood reduces its oxygen carrying
capacity which in turn impairs oxygen release into tissue, seriously affecting the functioning of
both the brain and the heart.
The amount of COHb in the blood can be measured and serves as an indicator of exposure to CO.
While the formation of COHb is a reversible process, it takes time for the body to metabolise the
CO and eliminate it.
Effects associated with CO exposure range from impairment in abilities that require sustained
attention and performance, headaches, dizziness, weakness, nausea, confusion, disorientation,
visual disturbances, unconsciousness up to death in extreme cases.
Typical CO concentrations
Air Quality Guideline Concentrations
NZ Ambient Air Quality Guideline
10 mg/m3 for 8 hour period
Typical New Zealand Urban Actual
5-10 mg/m3 for an 8 hour period
Typical New Zealand Rural Actual
<0.1 mg/m3 for an 8 hour period
Typical New Zealand Peak
up to 12 mg/m3 for an 8 hour period
Source: New Zealand Ministry for the Environment, 2001
New Zealand - Ministry for the Environment
Environmental Performance Indicators Programme
Air Quality Indicators
Nitrogen Oxides
Nitrogen oxides exist in the atmosphere as a number of species - nitric oxide (NO), nitrogen
dioxide (NO2), and nitrous oxide (N2O). Of these, NO2 (a reddish brown gas that is soluble in
water) is of most concern due to its resultant health effects. NO is also significant, however, as it
rapidly transforms to NO2 so NO and NO2 are often grouped together under the heading nitrogen
oxides (NOx).
Although NOx are produced naturally (from bacterial and volcanic action) in far greater total
quantities than from man-made activities, the natural quantities are widely dispersed over the
whole earth resulting in low background concentrations. In comparison, man-made production can
result in high local concentrations and is typically associated with the combustion of fossil fuels
(both stationary sources and mobile sources, such as transportation), and some industrial processes
(such as nitric acid production, the use of explosives, and welding).
NO2 in the human respiratory system causes increases in both the susceptibility to and the severity
of infections and asthma. Long term exposures can also weaken the effectiveness of the lung's
defences against bacterial infection.
In combination with other pollutants (notably sulphur dioxide and particulates), NO2 does have
some synergistic effects but the mechanisms at work are poorly understood.
NO2 has been reported as toxic to plants, especially in the presence of sulphur dioxide and ozone.
Typical NO2 Concentrations
NZ Ambient Air Quality Guideline
Typical New Zealand Urban Actual
Typical New Zealand Rural Actual
Typical New Zealand Peak
100 µg/m3 for 24 hour period
5-30 µg/m3 for 24 hour period
0-1 µg/m3 for 24 hour average
up to 50 µg/m3 for 24 hour period
Source: New Zealand Ministry for the Environment, 2001
New Zealand - Ministry for the Environment
Environmental Performance Indicators Programme
Air Quality Indicators
Sulphur Dioxide (SO2)
Sulphur Dioxide (SO2) is a colourless gas that reacts with moisture in the atmosphere to form
sulphuric acid aerosol (H2SO4).
SO2 is produced during the combustion of fossil fuels, especially coal and oil. Oil refining, steel
making and aluminium smelting are the industries mostly responsible for SO2 emissions.
Although generally not a significant problem in New Zealand, SO2 may be a significant pollutant
in regions where coal is used on domestic fires during winter.
SO2 is detectable by odour between 1300-3000 µg/m3. At concentrations above 10000 µg/m3, it
has a pungent irritating odour. At concentrations exceeding 10 000 µg/m3 SO2 becomes a
significant human health concern, increasing the likely hood of bronchitis and tracheitis. Unlike
Europe and the United States, sulphur dioxide is not believed to cause acid rain in New Zealand.
Maximum Recommended Concentrations
The MfE Ambient Air Quality Guidelines set the following levels for SO2 (Covered by Australian
Standard AS 3580.4.1.-1990):
Averaging Time
10 minute average
Hourly average of 10 minute means
24-hour average
Annual average
Ambient Air Quality Guideline
500 µg/m3
350 µg/m3
125 µg/m3
50 µg/m3
Source: New Zealand Ministry for the Environment, 2001
New Zealand - Ministry for the Environment
Environmental Performance Indicators Programme
Air Quality Indicators
Ground Level Ozone (O3)
Ozone (O3) is a very reactive compound present in both the outer reaches of the atmosphere
(stratosphere) and the closest parts of the atmosphere (troposphere). Human activities can lead to
increased tropospheric (ground level) ozone levels. When nitrogen oxides and volatile organic
compounds react in the presence of sunlight, ozone is formed.
Stratospheric ozone (measured in the Ozone Indicator) is not a pollutant, but tropospheric ozone
has been shown to have adverse health and environmental effects. In humans, ozone causes
changes to pulmonary function within 1 - 3 hours exposure, and coughing, thoracic pain, eye, nose
and throat irritation. Crop exposure to ozone levels of 100 µg/m3 can cause up to 22% yield
losses.
Because O3 takes some time to form, highest concentrations tend to occur away from large cities
in rural and forest areas. Also, ozone formation requires significant ultra violet light so harmfull
quantities of )3 are only likely to form during summer.
O3 is not usually discharged directly into the air. Sources of precursor gases (volatile organic
compounds and nitrogen oxides that form ozone as a product of chemical reactions) include
vehicles, vegetation, industry and domestic fires.
Current Levels
Conditions suitable for photochemical reactions may occur on up to 10, 15 and 4 days per year in
Auckland, Hamilton and Christchurch. On two days during 1977/78 ozone measured in Auckland
exceeded the MfE one hour guideline. Highest concentrations were measured away from the city.
More monitoring is required to gain a better understanding of the potential for ozone formation in
New Zealand.
Averaging Time
Ambient Air Quality Guideline
1 hour
150 µg/m3
8 hour
100 µg/m3
Source: New Zealand Ministry for the Environment, 2001
APPENDIX 4
Scottish Environmental Indicator Series
Air Quality Indicator Strategy Objectives
Indicator
Sulphur dioxide
Strategy Objective

15-min mean of 266 µg/m3 (100 ppb) not to be
exceeded more than 35 times per year by 31
December 2000.

1-hr mean of 350 µg/m3 (132 ppb) not to be
exceeded more than 24 times per year by 31
December 2004.

24-hr mean of 125 µg/m3 (47 ppb) not to be
exceeded more than 3 times per year by 31
December 2004.

Annual mean for the protection of vegetation 20
µg/m3 (8 ppb) by 31 December 2000 and 20 µg/m3
(8 ppb) winter average (October to March) by 31
December 2000.
Annual mean of 16.25 µg/m3 (5 ppb) by 31
December 2003.
Annual mean of 2.25 µg/m3 (1 ppb) by 31
December 2003.
Running 8-hr mean of 11.6 mg/m3 (10 ppm) by 31
December 2003.
Benzene

1,3-Butadiene

Carbon Monoxide

Lead

Oxides of Nitrogen

Annual mean of 0.5 µg/m3 by 31 December 2004
and 0.25 µg/m3 by 31 December 2008.
1-hr mean of 200 µg/m3 (105 ppb) not to be
exceeded more than 18 times per year by 31
December 2005.

Annual mean of
December 2005.
40
µg/m3
(21
ppb)
by
31

Annual mean for the protection of vegetation of 30
µg/m3 (16 ppb) by 31 December 2000.
Ozone

Particulates

8-hr mean of 100 µg/m3 (50 ppb) not to be
exceeded more than 10 times per year by 31
December 2005.
Annual mean of 40 µg/m3 by 31 December 2004.

24-hr mean of 50 µg/m3 by 31 December 2004.
Source: SEPA website, 2001
APPENDIX 5
MALTA
Ministry for the Environment
Environment Protection Department
AIR QUALITY MONITORING RESULTS
LOCALITY
MONITORING
PERIOD
ACTUAL
DAYS
MONITORED
PARAMETERS
MONITORED
EXCEEDANCE(S)*
days
% of days monitored
parameter
Vittoriosa
8-Sep-1999 to 23-Sep-1999
13
SO2, NO2, O3, PM10
3
23
PM10 LV
Siggiewi
1-Oct-1999 to 8-Oct-1999
8
SO2, NO2, O3, PM10
5
63
PM10 LV
Mosta
9-Oct-1999 to 19-Oct-1999
9
SO2, NO2, O3, PM10
3
33
PM10 LV
Fgura
17-Oct-1999 to 25-Oct-1999
6
SO2, NO2, O3, PM10
3
50
PM10 LV
Paola
27-Oct-1999 to 30-Oct-1999
3
SO2, NO2, O3, PM10
2
67
PM10 LV
Zabbar
1-Nov-1999 to 2-Nov-1999
2
SO2, NO2, O3, PM10
2
100
PM10 LV
Qormi
18-Nov-1999 to 26-Nov-1999
9
SO2, NO2, O3, PM10
6
67
PM10 LV
Kalkara
27-Nov-1999 to 9-Dec-1999
12
SO2, NO2, O3, CO, PM10
2
17
PM10 LV
Mellieha
10-Dec-1999 to 20-Dec-1999
11
SO2, NO2, O3, CO, PM10
6
55
PM10 LV
Ghajsielem
1-Jan-2000 to 20-Jan-2000
20
SO2, NO2, O3, CO, PM10
4
20
PM10 LV
Munxar
6-Feb-2000 to 9-Feb-2000
4
SO2, NO2, O3, CO, PM10
0
0
Mellieha
11-Feb-2000 to 21-Feb-2000
11
SO2, NO2, O3, CO, PM10
0
0
Qormi
22-Feb-2000 to 2-Mar-2000
9
SO2, NO2, O3, CO, PM10
1
11
PM10 LV
Kalkara
6-Mar-2000 to 10-Mar-2000
5
SO2, NO2, O3, CO, PM10
5
100
PM10 LV
Zabbar
11-Mar-2000 to 20-Mar-2000
9
SO2, NO2, O3, CO, PM10
6
67
PM10 LV
Rabat
15-Apr-2000 to 1-May-2000
17
SO2, NO2, O3, CO, PM10
3
18
PM10 LV
Marsa
2-May-2000 to 20-Aug-2000
50
SO2, NO2, O3, CO, PM10
38
76
PM10 LV
Marsa
2-May-2000 to 20-Aug-2000
50
SO2, NO2, O3, CO, PM10
3
6
SO2 LV
Marsa
2-May-2000 to 20-Aug-2000
50
SO2, NO2, O3, CO, PM10
1
2
SO2 AT
Swieqi
21-Aug-2000 to 7-Sep-2000
15
SO2, NO2, O3, CO, PM10
13
87
PM10 LV
Dingli
8-Sep-2000 to 28-Sep-2000
19
SO2, NO2, O3, CO, PM10
4
21
PM10 LV
San Gwann
16-May-2001 to 25-May-2001
9
SO2, NO2, O3
0
0
Floriana
26-May-2001 to 3-Jun-2001
8
SO2, NO2, O3, CO
0
0
Birzebbuga
4-Jun-2001 to 8-Jun-2001
5
SO2, NO2, O3, CO
0
0
*
occurrence when air quality standards were exceeded
Source: Environment Protection Department website, 2001