Emissions
of SO2 and NOx
UP-9
Urban
Environmental Problems
Pressure
1 Indicator
definition and unit of measurement
The
amount of emissions of sulphur dioxide (SO
2)
and nitrogen dioxide (NO
x)
in tonnes per year per capita emitted by human activities in urban areas.
2 Placement
in the framework
Chapter
5: The themes and targets of the programme, section 5.2: Acidification and air
quality (and section 5.5: The urban environment).
Agenda
21:
Chapter
9: Protection of the atmosphere.
International
conventions and agreements:
UNECE
LRTAP (Geneva, 1979), and its protocols on the stabilisation of NO
x
emissions
(Sofia, 1988), on the reduction of SO
2
emissions (Helsinki, 1985) and 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:
9
(16%)
Policy
Relevance:
6
(3.1)
Analytical
Soundness:
3
(3.1)
Responsiveness:
9
(2.6)
Most
appropriate related state indicator:
Concentrations
of SO
2
and NO
x.
3 Significance
Purpose:
The
amount of SO
2
and NO
x
per capita emitted by urban activities reflects energy consumption and mobility
patterns by the urban population. It also reflects various degrees of
compactness of the urban structure. The purpose of this indicator is to
evaluate the environmental performance of urban energy efficiency and
transportation strategies and to describe the pressure of urban areas on the
local and regional atmosphere.
Relevance:
Human
exposure to sulphur oxides and nitrogen oxides in cities contributes to
respiratory
morbidity
and mortality. These pollutants are also the source of important urban impacts
on air quality at larger scales through long distance transport in the
atmosphere. In the presence of sunlight, nitrogen oxides react with volatile
organic compounds (VOCs) to form tropospheric ozone.
Linkages
to other pressure indicators:
Per
capita emissions of SO
2
and
NO
x
in urban areas are linked to primary energy consumption (AP-6), energy use per
capita (RD-2), electricity production from fossil fuels (RD-5), share of
private car transport (UP-4), national SO
2
(AP-3)
and NO
x
emissions
(AP- 1).
Targets:
Related
to national and international targets for the reduction of SO
2
(AP-3)
and NO
x
(AP-1).
4 Methodological
description and underlying definitions
Underlying
definitions and concepts:
Trends
in the emissions of these pollutants reflect the effectiveness of urban
strategies aiming at reducing air pollution caused by urban activities. These
include land use planning, energy and transportation demand management,
pollution control policies, and technical measures designed to improve energy
conservation and efficiency and to create more sustainable urban life styles.
Measurement
methods:
Urban
emissions inventory are being developed by several cities. Sulphur dioxide and
nitrogen oxide emissions in urban areas are calculated by using emission
factors that reflect the presence of sulphur compounds in different processes
and activities:
Emission = (Emission factor) x (Activity level)
Limitations
of the indicator:
Major
limitations are due to the lack of national emissions factors and the diversity
of measurements methods adopted by different cities.
Alternative
definitions:
A
possible alternative is emissions of SO
2
and
NO
x
per capita disaggregated by activities.
