SmogRank / Countries / Slovenia / December 2025

Most polluted cities in Slovenia, December 2025

8 cities in Slovenia ranked by their average PM2.5 over the 31 days. Worst: Ptuj at 22.3 µg/m³, #310 of 2,360 cities in the world. Cleanest: Koper at 11.3. A city needs measurements on 70% of the days to be ranked.

  1. 1PtujUrban Municipality of Ptuj
    22.3
  2. 2KranjUrban Municipality of Kranj
    21.7
  3. 3Novo MestoUrban Municipality of Novo Mesto
    21.4
  4. 4CeljeUrban Municipality of Celje
    20.8
  5. 5LjubljanaLjubljana
    19.9
  6. 6TrbovljeMunicipality of Trbovlje
    18.2
  7. 7MariborUrban Municipality of Maribor
    14.0
  8. 8KoperUrban Municipality of Koper
    11.3
Good0–9.0
Moderate9.1–35.4
Sensitive groups35.5–55.4
Unhealthy55.5–125.4
Very unhealthy125.5–225.4
Hazardous225.5+

All cities in the world, December 2025 · Slovenia now

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SmogRank, most polluted cities in Slovenia, PM2.5, December 2025, smogrank.com/si/history/2025-12 (accessed 1 Oct 2026).

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