EPA - Ireland's Environment, An Integrated Assessment - 2020

Ireland’s Environment – An Integrated Assessment 2020 Ozone Ground-level ozone is formed when other air pollutants chemically react in the presence of strong sunlight. Ground-level ozone is formed as a secondary pollutant from the chemical reaction of nitrogen oxides, carbon monoxide and volatile organic compounds in the presence of sunlight. Ozone concentrations tend to be highest in spring and summer. Ozone is a greenhouse gas that affects our climate. Ozone can be present at ground level because of downwards movement from the ozone-rich stratosphere, where it occurs naturally and plays an important role in absorbing harmful ultraviolet radiation. Ozone is readily transported to Ireland from Atlantic and European regions as a result of the natural movement of air masses. Ground-level ozone is reduced through reactions with traffic-emitted pollutants; therefore, levels of ozone are higher in rural areas than in urban areas. Elevated concentrations of ozone can decrease lung function. It can also aggravate respiratory ailments in sensitive individuals such as those with asthma and lung disease (EEA, 2014). Normally, elevated concentrations of ground-level ozone in Ireland are caused by transboundary ozone from continental Europe. Ozone concentrations measured as 8-hour averages in Ireland for the period 2008-2018 show levels well below the maximum allowed number of exceedances per year (25 occurrences). In 2018, Valentia Observatory had the maximum number of exceedances in the network, at six. However, shorter-term ozone episodes do occur. During 2018, a hot and sunny spell of weather from 22 to 30 June led to an increase in ozone concentrations across the country (EPA, 2019b). The highest concentrations from the ozone monitoring network were observed at the rural background site in Kilkitt, County Monaghan, on 28 June 2018. During this episode, the concentrations reached ≈170 µg/m 3 . Had they reached 180 µg/m 3 , a public information alert would have been triggered to inform the public of the health impacts of elevated (raised) ozone concentrations. This episode shows that ground-level ozone could be a potential problem pollutant in Ireland if suitable weather conditions are experienced again in the future. Polycyclic Aromatic Hydrocarbons Polycyclic aromatic hydrocarbons are complex chemical compounds formed through the burning of solid fuel. Polycyclic aromatic hydrocarbons (PAH) are chemical compounds that consist of two or more fused aromatic rings made entirely from carbon and hydrogen. Sources of PAH include industry, traffic emissions and the domestic use of solid fuels such as peat, wood and coal. Long-term exposure to low levels of PAH may cause several diseases, including cancer (EEA, 2014). PAH, in the form of the compound benzo[a]pyrene (BaP), were first monitored in Ireland in 2009 at five monitoring stations. In 2018, levels at three of the four monitoring stations were above the EEA reference value (0.1 ng/m 3 ) but below the EU target value (1 ng/m 3 ). Figure 3.12 details annual mean concentrations of BaP across Europe in 2017 (EEA, 2019). Reductions in emissions from the domestic use of solid fuel are required to reduce ambient levels of PAH. Previous EPA research studies on levels of PAH in various towns throughout Ireland have highlighted elevated levels during the heating season in particular (Goodman et al. , 2015). Air monitoring station, Carrick-on-Shannon, Co. Leitrim, installed in September 2020. 76