According to the European Environment Agency's updated European city air quality data viewer, Dublin had the 35th best air quality in Europe in 2020-2021 while Cork had the 38th. The two other Irish cities featured were Limerick in 73rd place and Waterford in 130th place.

The viewer ranks cities from the cleanest to the most polluted, on the basis of average levels of fine particulate matter, or PM2.5, over the past two calendar years. Only 11 cities qualified as having good air quality, with Umeå in Sweden, and Faro and Funchal in Portugal having the cleanest. The air quality of the four Irish cities surveyed was classed as 'fair'. 

More than 340 cities are included in the European city air quality viewer. Cities are ranked from the cleanest to the most polluted based on average levels of fine particulate matter (PM_2.5). The data behind the ranking was collected from more than 400 monitoring stations across EEA member countries over the past two calendar years.

From 2020 to 2021, air quality was good in only 11 cities, meaning that levels of PM_2.5 were below the World Health Organization’s (WHO) health-based guideline for long-term exposure to PM_2.5 of 5 micrograms per cubic meter of air (5 μg/m³). The guideline was exceeded in 97% of the 343 European cities included in the viewer.

In contrast, the European Union’s (EU) annual limit value for PM_2.5 of 25 µg/m³ was only exceeded in the three most polluted cities, including Nowy Sacz, Poland, and Cremona and Padova in Italy, highlighting the difference between the WHO guideline and the EU standard.

The European city air viewer can be used to check how the air quality was in European cities over the past two years. The viewer focuses on long-term concentrations of PM_2.5, as long-term exposure to air pollution causes the most serious health effects, and PM_2.5 is the air pollutant with the highest impact on health in terms of premature death and disease.