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The main source of NO2 is transport (EEA, 2025a), which emits half of the annual NOX emissions in Europe. Road transport emissions happen close to the ground and mostly in densely populated areas. Therefore, the highest concentrations are generally reported in large, trafficked cities. Other important sources are combustion processes in agriculture, industry and energy supply.

The EEA has received valid 2024 NO2 data from 37 of the reporting countries (all, excluding Albania and Liechtenstein). Preliminary data for 2025 have been received from all the countries except Albania, Kosovo, Liechtenstein, Serbia and Türkiye.

The EU and the WHO have set different standards and AQG levels for both short- (hourly and daily) and long-term (annual) concentrations. They are presented in Table 4.

Table 4. EU air quality standards and WHO AQG levels for NO2

 

Current EU standard

 

2030 EU standard

 

WHO 2021 AQG level

 

Averaging period

Limit value

Not to be exceeded more than

Limit value

Not to be exceeded more than

AQG level

Comments

1 hour

200μg/m3

18 hours/year

200μg/m3

3 hours/year

  

24 hours

  

50μg/m3

18 days/year

25μg/m3

99th percentile (3-4 days/year)

1 calendar year

40μg/m3

 

20μg/m3

 

10μg/m3

 

Annual limit values and WHO AQG level

In 2024, concentrations above the current ALV were found in 2% of the reporting stations across six Member States (France, Germany, Greece, Italy, Poland and Portugal) and two other reporting countries (Serbia and Türkiye) as shown in Map 9 and Figure 8; 65.7% of them were traffic stations. Overall, 67.2% of the reporting stations registered concentrations above the WHO annual AQG level, 48.7% of which were traffic stations.

In addition to data collected from monitoring stations, countries can also use modelling applications to assess their compliance with the standards. Belgium, Italy and Poland reported NO2 ALV exceedances for one, one and two air quality zones, respectively, based on assessment models.

In 2025, 0.5% of monitoring stations registered concentrations of NO2 above the current ALV; 87% of these were traffic stations. They were located in four Member States (France, Germany, Greece and Italy) and Bosnia and Herzegovina, as shown in Map 9. Overall, 66.9% of monitoring stations registered concentrations above the WHO annual AQG level, 41.4% of which were traffic stations.

In 2024, 73% of the reporting stations registered concentrations below the EU 2030 ALV. All the concentrations reported in three Member states (Denmark, Estonia and Finland) as well as in Iceland and Montenegro were below the EU 2030 ALV.

Map 9. Concentrations of NO2 in 2024 and 2025 in relation to the EU annual limit values and the WHO annual AQG level

Figure 8. NO2 concentrations in 2024 by country in relation to the annual limit values and the WHO annual AQG level

Short-term limit values

In 2024, 34 Turkish stations (1.1% of all the European stations reporting NO2 data) registered concentrations above the current hourly limit value (HLV).

Overall, 98.5% of the reporting stations already had concentrations below the 2030 EU HLV. Germany, Italy and Spain each had one station, Latvia had two stations and Türkiye had 43 stations which registered concentrations above this 2030 EU HLV.

In 2024, 91.9% of reporting stations had concentrations below the 2030 DLV. All of the stations in ten Member States (Cyprus, Denmark, Estonia, Finland, Latvia, Luxembourg, Malta, Netherlands, Slovakia and Sweden) as well as those in Andorra, Iceland, Kosovo, Montenegro and Switzerland registered concentrations below the 2030 DLV in 2024 (Map 10).

Map 10. Concentrations of NO2 in 2024 in relation to the 2030 EU daily limit value

Figure 9 provides a summary of the NO2 stations above EU air quality limit values and WHO AQG levels.

Figure 9. Percentage of reporting monitoring stations registering NO2 concentrations above EU limit values and WHO AQG levels

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