Best and worst European cities for air quality

A snapshot of the cleanest and most polluted urban environments in 2024, with population-weighted PM2.5 rankings.

The cleanest cities

Across the 2024 EEA validated dataset, the cleanest large European cities — by population-weighted PM2.5 annual mean — were dominated by Nordic and Atlantic-fringe capitals. Stockholm, Helsinki, Tallinn, Oslo, and Dublin all sat below 8 µg/m³, putting them within striking distance of the WHO 2021 guideline of 5 µg/m³. Their advantages: high latitude with strong westerly winds dispersing pollution; near-total replacement of coal and oil home heating with district heating and electric heat pumps; low population density relative to land area; and dominant background flow from the relatively clean Atlantic.

The most polluted cities

The dirtiest large European urban environments in 2024 sat in two clusters. The first is southern Poland (Kraków, Katowice) and northern Czech Republic / Silesia, where Soviet-era coal-burning residential heating ("smog episodes" in winter) drives annual means above 20 µg/m³ even in nominally regulated urban areas. The second is the Po Valley in northern Italy (Milan, Turin, Brescia), where dense industry, agriculture, and a topography that traps still air below mountain ridges produce winter inversions with multi-week pollution episodes. Sofia (Bulgaria) and Bucharest (Romania) sit similarly high, again primarily from solid-fuel residential heating and older diesel vehicle fleets.

NO2 — a different geography

For NO2, the ranking changes. The dirtiest cities for traffic-source NO2 are the dense urban cores of Western Europe: central London (Marylebone Road, Knightsbridge), inner Paris (boulevards périphériques), and Rome (via Tiburtina, Cristoforo Colombo). These cities have lower PM2.5 because of cleaner residential heating and tighter industrial regulation, but they have higher NO2 because of dense, slow-moving diesel and gasoline traffic.

Ozone — a southern phenomenon

Ground-level ozone is a secondary pollutant formed in sunlight, so the highest annual means cluster in the Mediterranean: Athens, Naples, Madrid, Nicosia, and parts of southern Italy and Greece. Summer ozone episodes regularly exceed the EU 8-hour target value of 120 µg/m³ across this region.

Why "city" rankings can mislead

Comparing cities directly is tricky. Each city's reported value depends on which stations are used in the average — traffic-heavy networks (e.g. London) appear worse, while networks weighted toward background sites appear better. The EEA's population-weighted exposure metric, which uses a 1 km gridded population overlay (GHS-POP) and CAMS reanalysis, is more comparable across cities and countries than a raw station-mean. The figures cited here are EEA population-weighted estimates.

Source: European Environment Agency Air Quality e-Reporting Database, Dataflow E1a (validated annual).

Source: World Health Organization Global Air Quality Guidelines (2021 update).

Sources: European Environment Agency Air Quality e-Reporting; WHO Global Air Quality Guidelines 2021; EU Directive 2008/50/EC and the revised Directive (EU) 2024/2881; Copernicus Atmosphere Monitoring Service.