SmogRank / World / Europe / France / Brittany

Most polluted cities in Brittany, France

5 measured cities, this year; 5 above the WHO annual guideline. Worst: Rennes at 8.1 µg/m³, #1,769 in the world.

Ranked by unhealthy days: the share of each city's measured days with a daily mean over 35.4 µg/m³ (US AQI 101+), Unhealthy for Sensitive Groups or worse on the US EPA's scale. Ties go to the higher average.

Normandy: 10 measured citiesPays de la LoireBrittany: 5 measured citiesNew Aquitaine: 9 measured cities#5 Quimper: 7.2 µg/m³#4 Lorient: 7.4 µg/m³#3 Vannes: 7.6 µg/m³#2 Brest: 7.9 µg/m³#1 Rennes: 8.1 µg/m³
Each dot is a measured city, coloured by its PM2.5; tap a dot to open the city.
← Rennes 1% 0.75%0
Every measured city in Brittany, France, one column each, ranked by unhealthy days: height is the share of its measured days that were unhealthy, colour its average. Point at it to read a city; tap to open it.
  1. 1Rennes 1%
  2. 2Quimper 0%
  3. 3Brest 0%
  4. 4Vannes 0%
  5. 5Lorient 0%
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

The US EPA's Air Quality Index for PM2.5 (2024 breakpoints). Show values as: µg/m³ · US AQI · India AQI · China AQI · European AQI · UK DAQI · Canada AQHI+. About the scales

Estimated: cities without a monitor

Brittany cities we can't measure, with model estimates for the last 7 days. Listed by population, not ranked: estimates aren't precise enough to rank. Model estimates from the Copernicus Atmosphere Monitoring Service (CAMS), adjusted to measured cities nearby where there are any. Adjusted, a single day lands within ×1.5 of what a monitor would read about two times in three; unadjusted, it can be off by half or double. Treat them as a guide, not a measurement.

City7-day estimateBand
Saint-Brieuc≈ 6 µg/m³Good
Lanester≈ 6 µg/m³Good
Fougères≈ 5 µg/m³Good
Lannion≈ 6 µg/m³Good
Concarneau≈ 6 µg/m³Good
Ploemeur≈ 6 µg/m³Good
Morlaix≈ 6 µg/m³Good
Vitré≈ 5 µg/m³Good
Pontivy≈ 5 µg/m³Good
Douarnenez≈ 7 µg/m³Good
Cesson-Sévigné≈ 6 µg/m³Good
Landerneau≈ 6 µg/m³Good

Bad-air episodes in Brittany

Times when many cities around here had PM2.5 at twice their usual or more on the same days.

Use this board

SmogRank, most polluted cities in Brittany, France, PM2.5, this year to 6 Oct 2026, 22:00 UTC, smogrank.com/fr/region/brittany?w=year.

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms. Raw monitor readings in bulk are published by OpenAQ, under each provider's licence.

Updated 2026-10-06 22:07 UTC. Values are PM2.5 (fine particles), the median of each city's monitors, as the US AQI PM2.5 sub-index.