Emissions
of sulphur dioxide (SO2)
AP-3
Air
Pollution
Pressure
1 Indicator
definition and unit of measurement
The
total annual amount of sulphur dioxide emissions must be derived for all
economic activities, including energy production and transformation, industry,
transportation and domestic and tertiary sectors. The unit of measurement is Kt
SO
2
per year.
2 Placement
in the framework
5EAP:
Chapter
5: The themes and targets of the programme, section 5.2: Acidification and air
quality.
Agenda
21:
Chapter
9: Protection of the atmosphere.
International
conventions and agreements:
UNECE
LRTAP (Geneva, 1979), protocol on the reduction of SO
2
emissions (Helsinki, 1985) and protocol on further reductions of sulphur
emissions (Oslo, 1994). Proposal for a Council decision on the conclusion by
the EC of the Protocol to the LRTAP on further reduction of sulphur emissions
(COM(97)88) is under discussion with Member States (Directive to enter into
force by 1.6.98).
Ranking:
Core
ranking:
3
(51%)
Policy
Relevance:
5
(3.0)
Analytical
Soundness:
2
(3.2)
Responsiveness:
1
(3.0)
Most
appropriate related state indicator:
Atmospheric
concentration levels of aerosol sulphates.
3 Significance
Purpose:
Emissions
of sulphur dioxide arise primarily from the reaction of sulphur and oxygen
during the combustion of fossil fuels. The purpose of this indicator is to
identify the activities mostly responsible for the release of sulphur dioxide
into the atmosphere.
Relevance:
Sulphur
dioxide emissions are partly responsible for acid depositions on the surface
and the occurrence of winter smog episodes. In addition, the oxidisation of SO
2
has also been found to contribute to visibility degradation due to high
concentrations of aerosol sulphates in the atmosphere.
Linkages
to other pressure indicators:
Sulphur
dioxide emissions are also related to the Urban Environmental Problems policy
field (UP-9), as they are associated with the local occurrences of winter-type
smog episodes in large urban centres. The present definition of the indicator
refers to inter-boundary air pollution problems related to regional
concentration levels and exceedance of critical loads.
Targets:
The
Helsinki Protocol on sulphur emissions set a target for the reduction of SO
2
emissions by 30% below 1980 levels by 1993. The Oslo Protocol for further
reductions of sulphur emissions has set as a basic obligation the control and
reduction of sulphur emissions in order to ensure that depositions of oxidised
sulphur compounds do not exceed critical levels. EU target is a 35% reduction
from 1985 level by 2000.
4 Methodological
description and underlying definitions
Underlying
definitions and concepts:
The
main source of sulphur dioxide are anthropogenic sources and particularly
fossil fuel combustion activities. The total amount of SO
2
emissions is directly related to the amount of sulphur contained in the
different type
s
of fossil fuels, the employment of disulphurisation techniques, as well as the
combustion technology used. It must be noted that naturally occurring SO
2
emissions, for example from the eruption of volcanoes, are not to be taken into
account.
Measurement
methods:
Similarly
to NOx emissions, local authorities perform regular inspections in order to
determine the conformity of a number of works and activities with environmental
regulations. Sulphur dioxide emissions are measured (and regulated, where
appropriate) for a number of activities, for example electricity production
stations and large industrial installations. For those activities for which
direct measurements are not directly available, it is possible to estimate
emissions by considering the amount of fuel consumed, together with emission
factors related to particular combustion processes. In order, however, to
determine the appropriate emission factor for these activities it is imperative
to have relevant statistical data related to the fuel characteristics, and
machinery specifications, taking into account the effects of various control
techniques (e.g. disulphurisation units etc.). It must be noted that detailed
methodologies (such as the CORINAIR programme) already exist for the estimation
of SO
2
emissions from all anthropogenic activities.
Limitations
of the indicator:
The
level of detail required for various combustion processes and particularly data
related to the machinery characteristics might not be readily available for
certain activities. In this case, default emission factors can be used to
obtain estimates of the SO
2
emissions released into the atmosphere.
Alternative
definitions:
Emissions
of sulphur dioxide per capita (Kt SO
2/inhabitant).
