(c) Limitations of the Indicator: (i)This indicator quantifies air pollution resulting
from energy use only; thus it ignores pollutant emissions related to other activities,
such as those of the industrial and agricultural sectors. In general, these sectors are not
dominant sources for the pollutants discussed, but to some extent they do contribute to
total exposures. (ii) The indicator assumes that countries have adequate national
statistical services to enable an air pollutant release and transfer register/inventory to
be established. (iii) When interpreting this indicator, it should be read in connection
with the indicator for urban air quality. (iv) The level of detail required for various
combustion processes, particularly data related to machinery characteristics, might not
be readily available for certain activities. In this case, default emission factors from
existing sources of inventory compilation guidance should be used to obtain estimates
of the pollutant emissions released into the atmosphere. (d) Alternative Definitions/Indicators: Alternatively, the percentage change in
emissions over time (e.g. the percentage change in emissions between 1990 and the
most recent year) may be considered; that is, indexed emissions relative to a 1990
baseline. Normalized forms of indicators are useful for cross-country comparisons
(i.e. emissions per unit of gross energy use). ASSESSMENT OF DATA (a) Data Needed to Compile the Indicator: Quantities of emissions of air pollutants
from all energy-related activities, particularly from the electricity production and
transportation sectors. Proposed denominator for a normalized indicator: Unit of gross
energy use.
(b) National and International Data Availability and Sources: Most European
countries report emissions of air pollutants annually under the protocols of the
CLRTAP. Globally however, the main challenge concerning data is to increase the
frequency with which the data are collected, processed and updated at the national
level. Annual changes in emissions cannot be calculated unless annual data are
available. In a number of countries, the current practice still is to publish emission
inventories at five-year intervals. Additional efforts are needed to improve the
availability, completeness and comparability of data for air pollutant emissions.
