PM2.5 stands for particulate matter with a diameter of 2.5µm or less. These particles are emitted mainly from the combustion of solid fuels for domestic heating, industrial activities and road transport (EEA, 2024b). As with PM10, they can also come from natural sources and can form in the atmosphere. Agricultural ammonia emissions significantly contribute to their formation in this regard.

For compliance assessments, Member States can discount the contribution of natural sources to the total concentrations as these sources are out of their control, but in this status analysis, they have not been excluded.

PM2.5 concentrations above the EU annual limit value were seen in Italy, Türkiye and most of the Western Balkan countries (Map 2 and Figure 5). As for PM10, solid fuel use is the main reason for the situation in central and eastern Europe, together with an older vehicle fleet.

Map 2. Concentrations of PM2.5 in 2023 and 2024 in relation to EU annual limit values and WHO annual guideline level

Table 2. Summary country status for PM2.5 in 2023 and 2024

 

2023

2024

Number of reporting Member States/other countries

27/10(a)

26/7(c)

Number of Member States/other countries with at least one station > EU annual limit value (25µg/m3)

3/3

2/1

Number of Member States/other countries with at least one station > WHO annual guideline level (5µg/m3)

27/9(b)

25/6(d)

Number of Member States/other countries with at least one station > WHO daily guideline level (15µg/m3)

27/9

26/6

Notes:   (a) In Kosovo under UNSCR 1244/99, only data for the annual mean fulfil the criteria for minimum data coverage. (b) All reporting countries except Iceland. (c) Denmark did not report UTD data for PM2.5. In Serbia, only data for the annual mean fulfil the criteria for minimum data coverage. (d) All the reporting countries except Estonia and Iceland.

Source: Air Quality e-Reporting database  (EEA, 2025a).

Figure 4. Percentage of reporting monitoring stations registering PM2.5 concentrations above the EU annual limit value and WHO guideline levels

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In 2023, 1.2% of monitoring stations registered concentrations of PM2.5 above the EU annual limit value (Figure 4), 85% of which were urban and 12% suburban. In contrast, 92% of PM2.5 reporting stations registered concentrations above the WHO annual guideline level, 62% of which were urban and 25% suburban.

Figure 5. PM2.5 concentrations in 2023 by country in relation to the EU annual limit value and WHO annual guideline level