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Air Quality and Transboundary Emissions
39
The critical load can be determined
for specific ecosystems, e.g. fish
species, surface waters and habitat
types. Atmospheric deposition
by rain or directly by gases and
particulates in excess of the critical
load is termed an exceedance. The
EPA provides Ireland’s data on critical
loads to European analysis centres.
These include data on forests, natural
grassland, heathland and peatland
(Posch et al., 2011). These data
inform compliance and support the
development of future UNECE and
EU Strategies on Air Pollution.
The reduction of sulphur emission
and associated acidification recovery
over the past two decades is one
of Europe’s environmental success
stories. Figure 3.6 shows the average
accumulated exceedance of critical
loads of acidification in Ireland
modelled for the years 1990, 2000
and 2020. Future reductions are
projected to further reduce the
magnitude and extent of critical
load exceedances.
However, nitrogen deposition and
exceedance of nutrient nitrogen lead
to eutrophication in ecosystems and
remain problematic. Figure 3.7 shows
the average accumulated exceedance
of critical loads of eutrophication
modelled for the years 1990, 2000
and 2020. There has been little change
in exceedance of nutrient nitrogen since
1990 owing to the limited reductions
in nitrogen emissions. This is leading
to ecosystem changes including
biodiversity loss and is a challenge
for achievement of EU Habitats
Directive goals. Consequently there
is an increasing European focus on
nutrient nitrogen critical loads. The
development of combined soil-
vegetation models is required to
better assess these impacts, and
further action on emissions is needed.
Responses
European Union Legislation
The EU Directives on ambient air
quality (EP & CEU, 2004, 2008) set
limits and target values for ambient
concentrations of air pollutants harmful
to human health and the environment.
If any limits are exceeded, Member
States must implement measures to
ensure the air quality standards are
met. The four Dublin local authorities
have prepared an air quality
management plan to address the
2009 exceedance in nitrogen dioxide
in Dublin which was submitted to the
EU in December 2011 as required.
A range of European Union
legislation specific to sources, gases
or fuels is contributing to progress to
achieving NEC Directive ceilings (EP
and CEU, 2001b, 2009; CEU, 1996,
1999; CEC, 1993).
Emissions from Industry
Emissions from industry and the
power generation sectors are
currently controlled by IPPC licensing
and the implementation of the Large
Combustion Plant Directive. These
measures have achieved significant
reductions in NO
X
, SO
2
and PM
emissions in Ireland in recent years.
Road Transport
While new standards for car
emissions and the resultant
cleaner technology have curbed
emissions, this has been offset by
the sustained level of use of private
cars in particular. This trend must be
addressed to reduce emissions and
achieve compliance with the NEC
Directive for NO
X
, the CAFE Directive
for NO
2
and the Fourth Daughter
Directive for PAH. The actions set
out in
Smarter Travel - A Sustainable
Transport Future
(DOT, 2009) should
be implemented to improve air
quality. These include actions to
reduce travel demand, increase
alternatives to the private car and
improve the efficiency of motorised
transport.
Figure 3.7
Average Accumulated Exceedance of Critical Loads of Eutrophication in 1990, 2000 and 2020
(Source: Posch et al., 2011)
1990
eq ha
-1
a
-1
no exceedance
<200
200 - 400
400 - 700
700 - 1200
> 1200
2000
2020
forecast