WHO vs EU NO2 compliance across 28 European countries (2024)

Research question: how many European countries comply with the EU NO2 limit (40 µg/m³ annual mean), and how many comply with the substantially stricter WHO 2021 health-evidence guideline (10 µg/m³)?

Findings

In 2024, 0 of 28 European countries exceeded the EU Ambient Air Quality Directive limit of 40 µg/m³ as a national population-weighted annual mean. By contrast, 28 of 28 exceeded the substantially stricter WHO 2021 guideline of 10 µg/m³. The median country-level NO2 annual mean was approximately 19.4 µg/m³.

The highest national means in 2024 were Italy (23.8 µg/m³), Poland (22.8 µg/m³), and Hungary (22.6 µg/m³). The lowest were Estonia (11.2 µg/m³) and Sweden (12.4 µg/m³). Importantly, even the cleanest country in our dataset sits above the WHO 2021 guideline. Country-level NO2 is dominated by traffic emissions (especially diesel) and varies sharply between dense urban traffic stations and rural background sites within the same country.

Practical reading: most European countries are EU-legal for NO2 but no European country is in compliance with the WHO health-evidence guideline. The October 2024 revised EU directive will lower the EU annual limit to 20 µg/m³ by 2030 — bringing it closer to WHO but not in full alignment. Until then, the gap between legal compliance and health-safe exposure remains widest for NO2 of all regulated pollutants.

Country ranking

Rank Country NO2 (µg/m³) EU limit (40) WHO 2021 (10) Stations
1 Italy 23.8 within above 3
2 Poland 22.8 within above 2
3 Hungary 22.6 within above 1
4 Romania 22.4 within above 1
5 Belgium 22.3 within above 1
6 Greece 22.1 within above 1
7 Netherlands 21.7 within above 2
8 Bulgaria 21.6 within above 1
9 United Kingdom 21.4 within above 3
10 France 20.6 within above 3
11 Czech Republic 20.5 within above 1
12 Luxembourg 19.8 within above 1
13 Slovakia 19.6 within above 1
14 Germany 19.4 within above 3
15 Croatia 19.2 within above 1
16 Austria 18.9 within above 1
17 Spain 18.9 within above 2
18 Portugal 18.6 within above 1
19 Malta 18.4 within above 1
20 Cyprus 17.8 within above 1
21 Slovenia 17.8 within above 1
22 Denmark 16.8 within above 1
23 Ireland 14.8 within above 1
24 Lithuania 14.2 within above 1
25 Latvia 13.6 within above 1
26 Finland 13.5 within above 1
27 Sweden 12.4 within above 1
28 Estonia 11.2 within above 1

Methodology

The compliance table was generated by querying the countries table in the PlainAirQuality SQLite database for the column no2_annual_avg — the EEA-published population-weighted annual mean of NO2 (chemiluminescence reference per EN 14211) for the validated 2024 dataset. The compliance flags compare the per-country value against the EU limit (40 µg/m³ annual mean, Directive 2008/50/EC Annex XI) and the WHO 2021 guideline (10 µg/m³ annual mean).

Population weighting uses the same EEA methodology as for PM2.5 — gridded population (GHS-POP) combined with CAMS reanalysis NO2 fields, ensuring that dense traffic-exposed urban areas contribute proportionally more to the country figure than sparse rural areas. See our methodology page for full details, including the conversion between hourly station observations and the annual mean compliance metric.

Limitations

Country-level NO2 averages obscure the steep gradient between traffic stations (kerbside, 10 metres from a busy road) and urban background stations. A country with a "compliant" national mean can still have multiple traffic stations exceeding the EU limit; the EU directive requires compliance at every regulatory station, not just the population-weighted mean. For station-level NO2 readings, see the individual country detail pages.

Source

European Environment Agency Air Quality e-Reporting Database (Dataflow E1a, validated 2024). WHO 2021 Global Air Quality Guidelines. EU Ambient Air Quality Directive 2008/50/EC, as revised by Directive (EU) 2024/2881.