Range of 2025 average PM2.5(μg/m3) across regional cities decreases, 72 cities remained unchanged, and 163 new cities were added in 2025. In total, 104 cities recorded annual average concentrationsbelow the WHO PM2.5 annual average guideline of 5 μg/m3. Finland led all European countries with 25 cities below the guideline, followed by Sweden with 15 and Spain with 12. At the national level, trends were evenly split. Twenty-three countries recorded increases in annual average PM2.5 concentrations, while the largest relative increases. Switzerland rose from 7.3 μg/m3 to 9.7 μg/m, and Greece increased from 11.5 μg/m3 to 14.9 μg/m3, with Malta recorded the largest decrease, with its national annual Three countries, Estonia, lceland, and Andorra, reported national annual average PM2.5 concentrations below the WHO guideline level. However, eight countries, Bosnia and Herzegovina, North Macedonia, Serbia, Turkey, Moldova, Romania, Montenegro, and ui wu bud swn gt anoge suouuo podan pueod the highest relative polltion tie in the region. A total of 163 new cities were added to the Report in Europe in 2025. Among these, nine cities reported annual PM2.5 concentrations areas of the region. Five of the newly added cities recorded PM2.5 concentrations below 5 μg/m3, including two in Sweden and one each in Finland, Norway, and the United Kingdom. Germany contributed the largest number of new cities with 31, followed by the United Kingdom with 22and each of the Netherlands, Serbia, and Spain with 12. In 2025, 62% of stations producing data for the qualifying cities in this region were government-operated, s u o nd sn sdong u further supported by non-government stations.