Introduction
Air quality in Ireland is of a high standard across the country and is among the best in Europe. This is due largely to prevailing clean Atlantic air and a lack of large cities and heavy industry.
In Dublin and Cork emissions from traffic have resulted in levels of nitrogen dioxide and particulate matter that are approaching the specified EU limit values. Levels of particulate matter are also high in large towns where no ban on bituminous coal exists. Polycyclic Aromatic Hydrocarbons (PAH), which were measured for the first time in Ireland in 2009, are at the limit value in some areas in Ireland, suggesting that they could be a problem pollutant in the future.
One of the key issues for Ireland is to reduce its emissions of transboundary air pollutants in line with international commitments. This was achieved for three of the main acidifying air pollutants and ozone precursors – sulphur dioxide, volatile organic compounds and ammonia – but the emission levels of oxides of nitrogen are likely to remain high in the short term.
State and Impacts
The ambient air quality pollutants of most importance on an EU-wide level are nitrogen dioxide, particulate matter and ozone. They can impact on human health and are at levels approaching the relevant limit value or long-term objective.
Nitrogen Dioxide (NO2)
Nitrogen dioxide has a direct effect on health. Short-term exposure is associated with reduced lung function and airway responsiveness and increased reactivity to natural allergens. Long-term exposure is associated with increased risk of respiratory infection in children.
Nitrogen dioxide was measured at 13 stations in 2011. Concentrations of nitrogen dioxide were below the limit at all sites. Annual concentrations measured at suburban and rural sites are significantly lower than those measured at urban stations.
The trend in concentrations shows no discernible change in the last five years. While nitrogen dioxide concentrations are low in rural areas, higher levels in urban areas continue to pose a threat to compliance with the limit value.
Particulate Matter (PM10)
PM10 are very small particles which can penetrate deep into the respiratory tract. Inhalation of these particles can increase the risk, frequency and severity of respiratory and cardiopulmonary disorders.
PM10 was measured at 17 stations in 2011; all stations were compliant with the limit values. Levels were highest at traffic influenced sites in cities and in large towns due to burning of coal and other solid fuel in addition to emissions from traffic.
Levels of PM10 have remained stable during the last five years with a decreasing trend emerging at stations in Zone A (Dublin), Zone B (Cork) and Zone C (21 cities and towns with population >15,000). This may be attributed to decreases in emissions from traffic in the cities and large towns due to cleaner vehicles. The decrease is not seen in Zone D because levels in smaller towns and rural areas are influenced by a wider range of PM10 sources including emissions from residential fuel use, industry and agriculture.
Ozone (O3)
At ground level, higher concentrations of ozone in the air have adverse implications for human health and for crops and other vegetation. With respect to human health, high concentrations of ozone affect the functioning of the respiratory system.
Ozone was measured at 12 stations in 2011. Concentrations measured at all stations were below the target value. However, levels at four stations exceeded the long-term objective. Levels in Ireland are highly influenced by transboundary sources and are higher at the west coast than in the east of the country. In urban areas ozone is depleted through reactions with traffic-emitted pollutants, therefore levels of ozone are higher in rural areas than in urban areas.
Ozone concentrations are strongly influenced by meteorological conditions; higher levels of ozone occur in warm sunny conditions. Unlike most of mainland Europe, Ireland does not experience notable ozone pollution.
Drivers & Pressures
Main sources of pollutants
Emissions from road traffic are the main source of many air pollutants harmful to human health, including nitrogen dioxide, oxides of nitrogen, particulate matter, carbon monoxide, volatile organic compounds and heavy metals. In Dublin and Cork concentrations of nitrogen dioxide are close to the limit value at monitoring stations near busy roads.
The burning of coal and other solid fuel is also a source of particulate matter and other air pollutants including sulphur dioxide and polycyclic aromatic hydrocarbons. The ban on bituminous coal in large cities and towns has greatly reduced levels of particulate matter in those areas. The absence of a ban on bituminous coal in smaller towns means levels of particulate matter there are as high as levels in some cities.
Transboundary Pollution
Air pollution has a transboundary aspect meaning that emissions in one country can cause pollution in a different country. National emissions ceilings are in place across Europe to control emissions of four key transboundary pollutants: sulphur dioxide (SO2), oxides of nitrogen (NOx), volatile organic compounds (VOC) and ammonia (NH3). These pollutants can contribute to acidification, eutrophication and ozone formation.
Strategies implemented in Ireland in recent years have substantially reduced emissions of SO2, VOC and NH3, but levels of NOx are expected to remain high in the short term. Large increases in road transport are responsible for high NOx emissions levels. The benefits associated with increased penetration of catalyst control technology have been offset by increases in road traffic.
Responses
European Union Legislation
The Clean Air for Europe Directive (2008/50/EC) and the Fourth Daughter Directive (2004/107/EC) 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. A comprehensive monitoring network supplies real-time data on air quality to the public.
Emissions from Industry
The continued implementation and enforcement of existing policy measures is vital to maintain Ireland’s good air quality. Emissions from industry are currently not impacting on air quality due to the controls brought in by Integrated Pollution Prevention and Control (IPPC) licensing.
Bituminous Coal Ban
The ban on bituminous coal in large cities and towns has greatly reduced levels of particulate matter pollution in these areas. A widening of the ban to other areas would be expected to decrease levels of particulate matter across the country. A study on the effect of the bituminous coal ban found that that there were approximately 359 fewer cardiovascular and respiratory deaths per year in Dublin following the introduction of the ban.
Road Transport
While new standards for car emissions and the resultant cleaner technology have curbed emissions, this has been offset by the increasing number and bigger engine sizes of vehicles on Ireland’s roads. This growth in traffic must be curtailed to reduce NOx emissions and achieve compliance with the National Emissions Ceilings Directive (2001/81/EC).
Outlook
Overall, air quality in Ireland is expected to remain good, due largely to the prevailing clean westerly air-flow from the Atlantic and the relative absence of large cities and heavy industry.
However, ambient concentrations of nitrogen dioxide are likely to remain high in Dublin and Cork due to emissions from traffic. Levels of particulate matter are highest at traffic influenced sites in cities, and in towns with no ban on bituminous coal. Efforts are required to address both these sources, including reducing traffic emissions in cities and extending the ban on bituminous coal to other areas of the country. The Clean Air for Europe Directive (2008/50/EC) requires Member States to reduce the urban background concentrations of PM2.5. Ireland will need to reduce its average PM2.5 levels by 10 per cent by the year 2020. This will require an integrated approach across many sectors in Ireland, including the transport, residential and industrial sectors.
Emissions to Air
The EPA Integrated Pollution Prevention and Control licensing regime will continue to control emissions to air from industry to ensure that this sector will not impact on air quality. The strategies to achieve compliance with the EU Directive on National Emissions Ceilings have successfully controlled emissions of sulphur dioxide, ammonia and volatile organic compounds. Emissions of all three are expected to remain below the prescribed ceilings. Emissions of NOx are expected to remain above its ceiling, in the short-term, due to the difficulty in achieving large-scale reductions in emissions from road traffic.
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