Air Quality 2014 Summary

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The 2014 report details concentrations for a wide range of pollutants across the network. Overall air quality in Ireland for 2014 rates among the best in Europe. There were no exceedances of EU legislative target/ limit values. However, when compared to the non legislative, stricter World Health Organisation (WHO) guideline values and EEA reference levels, particular pollutants of note from an Irish context emerge.

Nitrogen oxides (NOx)

  • Measured at 17 stations
  • All sites were below the EU limit values and WHO guideline values

Trend

Levels of NOx across Ireland have remained relatively static since 2004, with signs of a slight increasing trend in the years 2008 - 2010 for Dublin and Cork traffic sites. However, NO2 levels decreased in general from 2010 to 2012. This downward trend appears to have stabilised with NO2 values showing something of an increase again in 2013 and 2014 at some locations, such as the Zone B traffic site (Cork). 

Outlook

Although NOx levels in Ireland in terms of ambient air quality are not exceeding limits, this may not always be the case. An increase in traffic volumes in an urban area allied to favourable meteorological conditions for air pollution may lead to an exceedance of the limit value in the future due to our continued reliance on motorised vehicles.

 

 NOx trend 2014

Ozone (O3)

  • Measured at 11 stations
  • All sites were below the EU legislative limit values
  • 8 sites exceeded the WHO guideline value

Trend

The figure belows details AOT40 (accumulated ozone threshold exposure above 40ppb) from 2004 to 2014 . This particular paramemter is used as an indicator of exposure by vegetation to ozone during the growing season. Ozone levels are higher in remote regions and tend to be highest along the western seaboard (indicated by the Galway and Kerry sites) and lower in the east of the country (indicated by the Monaghan site).

Outlook

Short acute ozone pollution episodes are infrequent in Ireland; however they have happened in the past and will happen in the future. They are most likely to occur in summer months when there is a stable anti-cyclone over Ireland bringing settled, warm weather. Movement of polluted air masses from Europe are more likely to occur during these periods, with the air masses likely to contain high levels of ozone. Given the transboundary nature of ozone, action at a European level will be required to tackle the issue

 

ozone trend 2014

 

Particulate Matter (PM10  / PM2.5)

PM10 measured at 20 stations

  • No EU legislative limit or target values exceeded
  • 2 sites exceeded the WHO guideline value

PM2.5 measured at 7 stations

  • No EU legislative limit or target values exceeded
  • 2 sites exceeded the WHO guideline value

PM10 Trend

The graphic below displays the trend in PM10 annual mean concentration from 2004 to 2014. In cities, traffic emissions are the main source of PM10, while in smaller towns or those areas not connected to the natural gas grid, emissions from residential solid fuel combustion dominate. Despite large differences in population number Zone D has similar PM concentrations compared to Zones A and B. This is most likely due to residential solid fuel emissions in Zone D which in this zone are a more significant source than traffic emissions.

PM10 Outlook

Episodes of elevated PM10 levels can occur at different times of the year in Ireland. The sources and composition of the PM10 can vary also, reflecting the dynamic nature of the emission profile of the pollutant.  The continued use of bituminous coal and other smoky fuels in rural areas outside the smoky coal ban areas are negatively impacting on air quality in these areas. PM10 emissions from farming activities through the increased use of fertilisers are expected to negatively impact on air quality, as ammonia from fertilisers are converted to particulate aerosols in the form of ammonium nitrate / ammonium sulphate.

Reduction in fossil fuel usage for a country is clearly a worthy goal; however the choice of fuel or energy source to replace those fossil fuels can impact on air quality. For example the adoption of renewable biomass energy as a strategy can lead to a balancing of the carbon equation; however biomass burning has a significant impact on air quality in the form of increased PM10 and PM2.5, in particular for inefficient wood burning.

This complex relationship between particulate matter and climate change policy has implications for Ireland and other EU Member States, looking to reduce PM2.5 concentrations for the NERT and at the same time reduce their carbon footprints.

 PM10 trend 2014

PM2.5 Trend

The graphic below details results at 7 stations from 2009 to 2014. Levels in Ireland are below both the limit values of 25  µg/m3With regards to WHO air quality guideline values, Ireland exceeds the WHO guideline value for PM2.5 at 2 of the 7 stations monitored in 2014.

PM2.5 Outlook

To date PM2.5 levels in Ireland have been below the EU limit value (25ug/m3). Trend analysis of historic data at sites containing both PM10 and PM2.5 show an increase in the ratio of PM2.5 to PM10. This suggests that human activities are leading to an increase in the amount of PM2.5 measured. This increase could be due to a number of different sources, given the variety of sources that contribute.Under the National Emissions Reduction Target (NERT) set for each country by the European Commission, Ireland’s obligation is to decrease PM2.5 concentrations by 10% by 2020. The timely implementation of sectoral emission reduction polices will be key to achieving this target.

 

2014 PM2.5 trend

Polycyclic aromatic hydrocarbons  (PAH)

  • Measured at 5 stations
  • No EU legislative limit or target value exceeded
  • 4 sites exceed the EEA reference value

Benzo (a) pyrene which is a marker compound for all PAH's was monitored at five stations across Ireland in 2014. There was insufficient data coverage (must be ≥85% for a valid year) at zone B and C stations to provide definitive results for the year and the levels at the zone A and D stations were below the EU legal target value of 1 ng/m3. The relatively high results detected at the Cork station though are a cause for concern and merit further investigation.

2014 PAH trend

Learn more

Full details of sampling for all parameters are contained within the report

Air Quality in Ireland 2014 - Key Indicators of Ambient Air Quality