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Figure 2.5
Annual Mean PM
10
Concentrations 2004‑2014 (Source: EPA)
Annual Limit Value
WHO air quality guideline
0
5
10
15
20
25
30
35
40
45
50
Annual Mean µg/m
3
Zone D
Zone C
Zone B Traffic
Zone A Background
Zone A Traffic
2014
2013
2012
2011
2010
2009
2008
2007
2006
2005
2004
2003
Ireland’s Environment – An Assessment 2016
28
Particulate Matter (PM
10
and PM
2.5
)
A priority for action because of health impacts
associated with this air pollutant which has both
urban and rural sources
PM
10
refers to particles with a diameter of less than 10
micrometres. These particles can penetrate the lungs,
while the related pollutant PM
2.5
refers to particles with
a diameter of less than 2.5 micrometres. This smaller
size allows them to penetrate the alveoli of the lungs,
where gaseous exchange occurs. In Ireland, the main
source of particulate matter in ambient air is agriculture
(through secondary formation) (EPA, 2015a). However,
in urban settings, domestic use of solid fuel and diesel
fuelled vehicular traffic are the principal sources. PM
10
concentrations have decreased in urban environments
since the early 2000s, mainly as a result of the shift from
residential solid fuel and developments in diesel particulate
filter technology. The picture in smaller towns and villages
in Ireland is different, where the predominant source of PM
is combustion of solid fuel. Because of the lack of access
to cleaner alternative heating sources such as gas, and
also the absence of a ban on the burning of smoky coal,
there has been no observed decrease in PM concentrations
over the same period (EPA, 2015b). As part of the EU
CAFE Directive, the National Exposure Reduction Target
(NERT) requires a mandatory 10% reduction in the average
concentration of PM
2.5
across Ireland by the year 2020. This
is a challenging reduction and will require an integrated
approach across a number of sectors including industrial,
agricultural, transport and residential emissions. Figure
2.5 shows annual concentrations from 2004 to 2014 for
monitoring sites across Ireland, with reference to the EU
limit value and the WHO air quality guideline value for
PM
10
. As can be seen from the graph, at certain monitoring
locations in Ireland values are above the WHO air quality
guideline levels (WHO, 2016).
Polycyclic Aromatic Hydrocarbons (PAHs)
Pollution sources linked to emissions from traffic and
household use of solid fuel
PAHs are organic compounds predominantly originating
from solid fuel burning, particularly wood burning and,
to a lesser extent, vehicle emissions. PAHs in Ireland are
measured by monitoring for benzo[a]pyrene (BaP), which
acts as a marker for PAHs and is a potent carcinogen (EEA,
2015). PAH monitoring in Ireland began in 2009, with
levels at one of the stations coming close to the limit value
of 1ng/m
3
in 2014. A reduction in the use of solid fuel as
a home-heating source across Ireland would mitigate PAH
impact on air quality into the future.
Ground-level Ozone (O
3
)
Not a direct emission but formed as a result of a
reaction of a mix of air pollutants during sunny weather
Ozone is a gaseous species that is formed as a secondary
pollutant in the ground level atmosphere from the
chemical reaction of NO
X
, CO and VOCs in the presence
of sunlight. Ozone can also be present in the troposphere
as a result of downwards flux from the ozone-rich