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

Ireland’s Environment – An Integrated Assessment 2020 4. Air Pollutants Monitored in the National Ambient Air Quality Monitoring Network The EPA and partner bodies assess a range of air pollutants as part of the Irish air quality monitoring network. The EPA and partner bodies use data from the National Ambient Air Quality Monitoring Network to assess levels of air pollutants. These include nitrogen oxides, sulphur dioxide, carbon monoxide, ground-level ozone, particulate matter (PM 10 and PM 2.5 ), benzene, heavy metals and polycyclic aromatic hydrocarbons (PAH). Across Europe, the most problematic pollutants have consistently been particulate matter, nitrogen oxides and ozone but, recently, PAHs have also been identified as pollutants of concern. The following section details the assessments of monitoring results for these four pollutants in Ireland. Particulate Matter Particulate matter in air consists of very small particles that have a very big impact on health. Particulate matter is a mixture of very small solid or liquid particles suspended in air. Primary particulate matter is emitted directly into the atmosphere from natural and human activities, while secondary particulate matter is formed in the atmosphere from precursor compounds. Particulate matter is usually referred to as PM with a number after it to show how small the particles are. The EPA monitors two types of PM, namely PM 10 and PM 2.5 , and compares levels with limit values in the CAFE (Clean Air for Europe) Directive (2008/50/EC) and WHO guidelines. PM 10 means that the particulate matter is 10 microns or less in diameter, 1/10th the width of an average human hair. PM 2.5 signifies particulate matter of 2.5 microns or less in diameter – 1/40th the width of an average human hair. While PM 10 particles can penetrate and lodge deep inside the lungs, PM 2.5 is even more health-damaging. These fine particles can penetrate the lungs and enter the blood system. Long-term exposure to particulate matter contributes to the risk of developing cardiovascular and respiratory diseases, as well as lung cancer (WHO, 2018). In Ireland the dominant sources of particulate matter from human activities are: n solid fuels used in home heating in winter n the transport sector n agricultural activities, particularly the formation of secondary particulate matter from nitrogen use. Figure 3.6 illustrates the annual mean levels of PM 10 in Ireland from 2009 to 2019. The annual averages were well within the annual limit value of the EU standard. However, in recent years there have been breaches of the WHO annual guideline value of 20 μg/m 3 , including in Zone C (towns > 15,000 inhabitants) for 2014. Concentrations at the suburban background monitoring site in Rathmines (Zone A background on the graph) – which is influenced by a variety of sources, including residential heating – were in the range of 13-17 μg/m 3 over the period, which is below the WHO guideline value. At both traffic monitoring sites in Cork and Dublin, the concentrations of PM 10 have slightly decreased, possibly because of reduced emissions from newer vehicles. For the most recent year, 2019, PM 10 was monitored at 30 sites. While there were no exceedances of the EU limit value (annual or daily), the WHO air quality daily guideline value of 50 μg/m 3 was exceeded at 14 monitoring stations (EPA, 2020). The WHO annual guideline value of 20 μg/m 3 was not breached. Figure 3.7 displays annual mean levels of PM 2.5 from 2009 to 2019. Levels of PM 2.5 have been in exceedance of the WHO air quality guideline value at all monitoring locations since 2009. In 2019, both Dublin (Zone A) and Ennis (Zone C) exceeded the WHO air quality guideline value (Topic Box 3.2). The highest concentrations were measured in large towns of > 15,000 inhabitants (Zone C) and rural locations (Zone D) when compared with both Cork and Dublin. In 2019, PM 2.5 was monitored at 30 stations. There were no exceedances of the EU annual limit value. However, the WHO air quality guideline annual value of 10 μg/m 3 was exceeded at ten monitoring stations. The WHO air quality daily guideline value of 25 μg/m 3 was exceeded at 25 monitoring stations. Numerous transboundary particulate matter events were measured in spring 2019. 70