SmogRank / Episodes / France

France and Germany, December 2025

For 2 days, from 17 to 18 December 2025, 10 cities in France and Germany had PM2.5 at least twice their usual for the time of year. The worst reading was Annemasse, Auvergne-Rhône-Alpes, France: 33.3 µg/m³ on 17 December, about 3.1× its usual 10.9.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached10in 2 countries
Days217 to 18 December 2025
Worst day17 December8 cities counted
Furthest above usual3.4×Montbéliard

Day by day

17 December 8 cities at twice their usual or more
MulhouseBaselLörrachMüllheimBernÉpinalFreiburgKehlNancyZürichVillingen-SchwenningenSaint-AvoldWinterthurSaarbrückenBaden-BadenVölklingenMetzDillingenAlbertvilleKarlsruheThionvilleKaiserslauternEggenstein-LeopoldshafenHerrenbergKonstanzPforzheimBourg-en-BresseChambéryEsch-sur-AlzetteTübingenTrierLuxembourgSaint-DizierBellinzonaReutlingenLudwigshafen am RheinWieslochLuganoMannheimFriedrichshafenStuttgartWormsHeidelbergLampertheimLudwigsburgMeylanLindauVillefontaineMeyzieuBensheimRiedstadtMainzVillefranche-sur-SaôneBiberach an der RißRüsselsheim am MainWiesbadenDarmstadtMichelstadtHattersheimKönigstein im TaunusEschbornFrankfurt am MainUlmNeu-UlmSchwäbisch HallRomans-sur-IsèreGroßostheimMarche-en-FamenneHanau am MainAschaffenburgKempten (Allgäu)AalenValenceSaint-ÉtienneLauda-KönigshofenAuxerreReimsWürzburgMoulinsVichyNeversAugsburgAnsbachCoulommiersClermont-FerrandMontargisStarnbergInnsbruckSaint-QuentinFontainebleauNurembergBambergIngolstadtMontluçonMunichBourgesCreilParisDomontÉtampesKelheimOrléansOlivetAurillacAmiensBeauvaisRambouilletChâteaurouxSchwandorf in BayernWeidenTraunreutChartresMarktredwitzBloisDreuxSaalfelden am Steinernen MeerBurghausenSalzburgLimogesÉvreuxLouviersSokolovRouenDieppeGrenobleLyonBad KreuznachStrasbourgLunévilleHeilbronnMontbéliardSpeyerAnnemasseFilderstadt
14 Dec15161718192021
Every measured city in the area, coloured by its PM2.5 that day; a dark ring marks a city at twice its usual or more. Bars: cities counted each day, coloured by their median level. Choose a day or press play; without JavaScript, the days link to that day's world ranking.

How it spread

AnnemasseAnnemasse, 14 December: 16.7 µg/m³, 1.5× usualAnnemasse, 15 December: no readingAnnemasse, 16 December: no readingAnnemasse, 17 December: 33.3 µg/m³, 3.1× usualAnnemasse, 18 December: 22.5 µg/m³, 2.1× usualAnnemasse, 19 December: 23.1 µg/m³, 2.1× usualAnnemasse, 20 December: 25.9 µg/m³, 2.4× usualAnnemasse, 21 December: 21.2 µg/m³, 1.9× usualGrenobleGrenoble, 14 December: 19.5 µg/m³, 1.5× usualGrenoble, 15 December: no readingGrenoble, 16 December: no readingGrenoble, 17 December: 30.3 µg/m³, 2.3× usualGrenoble, 18 December: 18.5 µg/m³, 1.4× usualGrenoble, 19 December: 12.7 µg/m³, 1.0× usualGrenoble, 20 December: 18.3 µg/m³, 1.4× usualGrenoble, 21 December: 21.0 µg/m³, 1.6× usualLyonLyon, 14 December: 19.2 µg/m³, 1.6× usualLyon, 15 December: no readingLyon, 16 December: no readingLyon, 17 December: 30.0 µg/m³, 2.4× usualLyon, 18 December: 14.5 µg/m³, 1.2× usualLyon, 19 December: 8.9 µg/m³, 0.7× usualLyon, 20 December: 12.2 µg/m³, 1.0× usualLyon, 21 December: 12.6 µg/m³, 1.0× usualSpeyerSpeyer, 14 December: 15.4 µg/m³, 1.5× usualSpeyer, 15 December: 11.5 µg/m³, 1.1× usualSpeyer, 16 December: 15.5 µg/m³, 1.5× usualSpeyer, 17 December: 29.5 µg/m³, 2.9× usualSpeyer, 18 December: 23.0 µg/m³, 2.2× usualSpeyer, 19 December: 17.4 µg/m³, 1.7× usualSpeyer, 20 December: 28.1 µg/m³, 2.7× usualSpeyer, 21 December: 18.9 µg/m³, 1.8× usualMontbéliardMontbéliard, 14 December: 9.9 µg/m³, 0.9× usualMontbéliard, 15 December: no readingMontbéliard, 16 December: no readingMontbéliard, 17 December: 26.7 µg/m³, 2.4× usualMontbéliard, 18 December: 31.6 µg/m³, 2.9× usualMontbéliard, 19 December: 41.2 µg/m³, 3.8× usualMontbéliard, 20 December: 31.8 µg/m³, 2.9× usualMontbéliard, 21 December: 19.7 µg/m³, 1.8× usualFilderstadtFilderstadt, 14 December: 10.6 µg/m³, 1.4× usualFilderstadt, 15 December: 9.3 µg/m³, 1.2× usualFilderstadt, 16 December: 13.3 µg/m³, 1.7× usualFilderstadt, 17 December: 25.9 µg/m³, 3.4× usualFilderstadt, 18 December: no readingFilderstadt, 19 December: no readingFilderstadt, 20 December: no readingFilderstadt, 21 December: no readingLunévilleLunéville, 14 December: 7.6 µg/m³, 0.8× usualLunéville, 15 December: 11.1 µg/m³, 1.2× usualLunéville, 16 December: no readingLunéville, 17 December: 25.4 µg/m³, 2.8× usualLunéville, 18 December: 11.1 µg/m³, 1.2× usualLunéville, 19 December: 7.9 µg/m³, 0.9× usualLunéville, 20 December: 11.1 µg/m³, 1.2× usualLunéville, 21 December: 23.1 µg/m³, 2.5× usualStrasbourgStrasbourg, 14 December: 11.7 µg/m³, 1.1× usualStrasbourg, 15 December: no readingStrasbourg, 16 December: no readingStrasbourg, 17 December: 25.0 µg/m³, 2.4× usualStrasbourg, 18 December: 26.0 µg/m³, 2.5× usualStrasbourg, 19 December: 12.4 µg/m³, 1.2× usualStrasbourg, 20 December: 21.2 µg/m³, 2.0× usualStrasbourg, 21 December: 17.3 µg/m³, 1.6× usualHeilbronnHeilbronn, 14 December: 15.3 µg/m³, 1.6× usualHeilbronn, 15 December: 9.7 µg/m³, 1.0× usualHeilbronn, 16 December: 15.7 µg/m³, 1.7× usualHeilbronn, 17 December: 23.0 µg/m³, 2.5× usualHeilbronn, 18 December: 27.3 µg/m³, 2.9× usualHeilbronn, 19 December: 23.7 µg/m³, 2.5× usualHeilbronn, 20 December: 22.4 µg/m³, 2.4× usualHeilbronn, 21 December: 13.8 µg/m³, 1.5× usualBad KreuznachBad Kreuznach, 14 December: 7.4 µg/m³, 0.7× usualBad Kreuznach, 15 December: 13.4 µg/m³, 1.4× usualBad Kreuznach, 16 December: 11.9 µg/m³, 1.2× usualBad Kreuznach, 17 December: 20.2 µg/m³, 2.0× usualBad Kreuznach, 18 December: 25.0 µg/m³, 2.5× usualBad Kreuznach, 19 December: 23.2 µg/m³, 2.3× usualBad Kreuznach, 20 December: 26.4 µg/m³, 2.7× usualBad Kreuznach, 21 December: 14.2 µg/m³, 1.4× usual14 Dec15161718192021
Every counted city, in the order the episode reached them, 3 days before to 3 after. Each square is a day, coloured by that day's PM2.5; outlined: at twice the city's usual or more.
Good0–50
Moderate51–100
Sensitive groups101–150
Unhealthy151–200
Very unhealthy201–300
Hazardous301+

Every city it reached

CityDaysHighestUsualAbove usual
MontbéliardBourgogne-Franche-Comté, France2 41.219 December10.93.8×
FilderstadtBaden-Wurttemberg, Germany1 25.917 December7.73.4×
AnnemasseAuvergne-Rhône-Alpes, France1 33.317 December10.93.1×
HeilbronnBaden-Wurttemberg, Germany1 27.318 December9.32.9×
SpeyerRheinland-Pfalz, Germany1 29.517 December10.32.9×
LunévilleGrand Est, France1 25.417 December9.12.8×
Bad KreuznachRheinland-Pfalz, Germany1 26.420 December9.92.7×
StrasbourgGrand Est, France2 26.018 December10.52.5×
LyonAuvergne-Rhône-Alpes, France1 30.017 December12.32.4×
GrenobleAuvergne-Rhône-Alpes, France1 30.317 December13.22.3×

Daily means in µg/m³. Usual: the city's median for this time of year (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that.

Against other episodes in France and Germany

Number 35 of 42 episodes in France and Germany since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 42.

Use this page

SmogRank, France and Germany, December 2025: 10 cities with PM2.5 at twice their usual or more, 17 to 18 December 2025, smogrank.com/episodes/2025-12-france-and-germany (accessed 2 October 2026).

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You're welcome to reuse a single chart, image or figure with this citation and a link. Terms.

An episode is a run of days when many cities close to each other (four or more within 350 km on a day, 8 or more in all) each had a daily PM2.5 mean of at least 25 µg/m³ and at least 2 times their usual for that time of year. Found in our own measurements, not picked by hand. How we find episodes. Values are each city's daily mean of its own monitors; causes are the usual kinds for a pattern like this, not a confirmed source.