Ireland's State of the Environment Report 2024

49 Chapter 2: Air Recorded levels of NO 2 have generally been below the EU annual limit value of 40 μg/m 3 . However, Ireland exceeded the annual limit for NO 2 in 2019 at the St. Johns Road West monitoring station in Dublin when the station measured an annual average concentration of 43 μg/m3 (EPA, 2020). Measures to combat this were set out in an air quality plan (DCC et al. , 2021) submitted to the European Commission in December 2021. There were no further exceedances in 2020, 2021, 2022 or 2023. As transport emissions are one of the most significant elements that affects air quality in Ireland, the Urban Transport Related Air Pollution Working Group acts as a subgroup of the new Clean Air Strategic Implementation Group. It is a joint working group of DECC and the Department of Transport providing a forum for ongoing engagement among the key transport stakeholders. Actions such as the roll-out of no idling campaigns at schools, whereby drivers of all parked vehicles are requested to turn off their engines, should be progressed. Annual NO 2 levels recorded at individual stations show that heavily trafficked cities and towns, i.e. Dublin (zone A), Cork (zone B) and large towns (zone C), would not meet the more stringent WHO air quality guideline limits for NO 2 (10 μg/m 3 ). Studies, including modelling conducted by the EPA (EPA, 2019, 2023a), have shown high indicative concentrations in locations in Dublin where the requirements of the directives on air quality do not apply, such as on the carriageway of the M50 and at major junctions, and also in areas not directly covered by the monitoring network. In partnership with Dublin City Council, the EPA is conducting further NO 2 tube studies in areas with the highest indicative concentrations. Ozone Ground-level O 3 is formed as a secondary pollutant when other air pollutants chemically react in the presence of strong sunlight. Elevated concentrations of ground- level O 3 can decrease lung function and also aggravate respiratory ailments in sensitive individuals such as those with asthma or a lung disease. O 3 is readily transported to Ireland from Atlantic and European regions by the natural movement of air masses. O 3 concentrations tend to be highest in spring and summer and are a combination of transboundary O 3 and locally produced O 3 . Concentrations of ground-level O 3 are reduced through its reaction with traffic-emitted pollutants; therefore, levels of O 3 are higher in rural areas than in urban areas. O 3 concentrations in Ireland for the period 2008-2023, measured as 8-hour averages, show levels generally well below the maximum allowed number of exceedances per year (25 occurrences). In recent years, there have been short periods of time when O 3 levels were high. This has occurred after periods of hot and sunny weather, which facilitates the build-up and formation of O 3 . Ground- level O 3 could become a problematic pollutant in Ireland during sustained hot and sunny weather conditions in the future. Of concern from a transboundary point of view are continental O 3 and particulate matter events, which occur most often during summer and spring, respectively. Other air pollutants The EPA monitors a range of other air pollutants. These include SO 2 , CO, volatile organic compounds (benzene, toluene, ethylbenezene, m- and p-xylene and o-xylene), heavy metals (lead, arsenic, cadmium and nickel) and polycyclic aromatic hydrocarbons. Ireland meets the current EU limit values for these pollutants but is above the WHO air quality guideline limits for SO 2 and the EEA reference level for polycyclic aromatic hydrocarbons. Impact of revision of ambient air quality directives The updated WHO guideline limits (see Topic Box 2.1) are tighter than current EU legislation (EC, 2022). In particular, the annual average guideline limits for PM 2.5 have been halved (from 10 μg/m 3 to 5 μg/m 3 ) and for NO 2 have been reduced to a quarter of the previous level (from 40 μg/m 3 to 10 μg/m 3 ) (WHO, 2021). Table 2.3 identifies the number of national ambient air monitoring stations that, while meeting current EU levels, were above the WHO air quality guideline limits based on the data collected in 2023. Specifically, 80 out of the 101 stations monitored in 2023 for PM 2.5 , the pollutant with the greatest impact on health, did not meet the WHO air quality guidelines. For NO 2 a similar picture was found, with 29 of the 36 stations monitored for this pollutant not meeting the WHO air quality guidelines. Similarly, WHO air quality guidelines were not met for PM 10 , SO 2 and O 3 . The revision of the ambient air quality directives moves EU limit values towards the tighter WHO air quality guidelines.