SmogRank / Episodes / France
France, Belgium and Germany, April 2023
For 2 days, from 17 to 18 April 2023, 36 cities in France, Belgium and Germany had PM2.5 at least twice their usual for the time of year. The worst reading was Dreux, Centre-Val de Loire, France: 32.8 µg/m³ on 18 April, about 4.8× its usual 6.9.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 36 in 3 countries
Days 2 17 to 18 April 2023
Worst day 18 April 28 cities counted
Furthest above usual 5.4× Le Mans
Day by day
Play 18 April 28 cities at twice their usual or more
Coulommiers Melun Fontainebleau Épernay Reims Calais Koksijde Olivet Troyes Auxerre Lochristi Charleroi Blois Brussels Canterbury Bourges Willebroek Zwijndrecht Saint-Dizier Antwerp Stabroek Kapellen Clacton-on-Sea Aarschot Tours Seaford Joué-lès-Tours Verdun Canvey Island Grays Brighton Breda Mol Bexley Flémalle-Haute Dagenham Ridderkerk Dijon Tilburg London Esch-sur-Alzette Eindhoven Luxembourg Hayes Thionville Metz Eupen Nancy Heerlen Aachen Portsmouth Venray Vesoul Reading Nijmegen Jülich Trier Besançon Southampton Mönchengladbach Jüchen Forbach Bergheim Andover Oxford Saarbrücken Düsseldorf Köln Nantes Ratingen Leverkusen Bonn Oberhausen Couëron Solingen Essen Borken Wuppertal Gelsenkirchen Hattingen Mulhouse Koblenz Bendorf Saint-Nazaire Datteln Dortmund Kehl Müllheim Basel Lüdenscheid Saint-Brieuc Schwerte Lörrach Freiburg Limburg an der Lahn Vannes Wiesbaden Baden-Baden Netphen Mainz Worms Eggenstein-Leopoldshafen Karlsruhe Speyer Ludwigshafen am Rhein Rüsselsheim am Main Mannheim Lampertheim Newport Soest Eschborn Cardiff Bensheim Villingen-Schwenningen Darmstadt Warstein Heidelberg Wiesloch Lorient Frankfurt am Main Pforzheim Gießen Newton Abbot Zürich Marburg an der Lahn Roubaix Sainte-Geneviève-des-Bois Valenciennes Amiens Lille Beveren Saint-Quentin Le Havre Roeselare Izegem Gent Maldegem Krefeld Paris Dieppe Duisburg Menen Beauvais Evergem Mons Rennes Kortrijk Caen Rouen Étampes Liège Évreux Rambouillet Lisieux Chartres Alençon Dreux Andenne Tournai Angers Le Mans 14 Apr 15 16 17 18 19 20 21 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
Kortrijk Kortrijk, 14 April: 4.6 µg/m³ Kortrijk, 15 April: 9.5 µg/m³ Kortrijk, 16 April: 8.6 µg/m³ Kortrijk, 17 April: 32.4 µg/m³, 3.7× its usual 8.8 Kortrijk, 18 April: 28.5 µg/m³, 3.2× its usual 8.9 Kortrijk, 19 April: 18.7 µg/m³ Kortrijk, 20 April: 13.7 µg/m³ Kortrijk, 21 April: 18.0 µg/m³ Evergem Evergem, 14 April: 5.1 µg/m³ Evergem, 15 April: 9.9 µg/m³ Evergem, 16 April: 8.4 µg/m³ Evergem, 17 April: 29.3 µg/m³, 3.3× its usual 8.9 Evergem, 18 April: 32.1 µg/m³, 3.5× its usual 9.1 Evergem, 19 April: 16.3 µg/m³ Evergem, 20 April: 17.5 µg/m³ Evergem, 21 April: 17.2 µg/m³ Izegem Izegem, 14 April: 4.9 µg/m³ Izegem, 15 April: 9.8 µg/m³ Izegem, 16 April: 8.4 µg/m³ Izegem, 17 April: 29.0 µg/m³, 3.0× its usual 9.7 Izegem, 18 April: 29.1 µg/m³, 3.0× its usual 9.8 Izegem, 19 April: 18.5 µg/m³ Izegem, 20 April: 12.6 µg/m³ Izegem, 21 April: 18.1 µg/m³ Menen Menen, 14 April: 6.1 µg/m³ Menen, 15 April: 9.2 µg/m³ Menen, 16 April: 8.6 µg/m³ Menen, 17 April: 28.8 µg/m³, 3.2× its usual 8.9 Menen, 18 April: 29.2 µg/m³, 3.2× its usual 9.0 Menen, 19 April: 19.3 µg/m³ Menen, 20 April: 13.5 µg/m³ Menen, 21 April: 18.2 µg/m³ Roubaix Roubaix, 14 April: 5.6 µg/m³ Roubaix, 15 April: 9.5 µg/m³ Roubaix, 16 April: 6.9 µg/m³ Roubaix, 17 April: 28.6 µg/m³, 2.4× its usual 11.9 Roubaix, 18 April: 27.0 µg/m³, 2.3× its usual 11.7 Roubaix, 19 April: 17.7 µg/m³ Roubaix, 20 April: 11.4 µg/m³ Roubaix, 21 April: 18.7 µg/m³ Tournai Tournai, 14 April: 1.7 µg/m³ Tournai, 15 April: 6.0 µg/m³ Tournai, 16 April: 5.6 µg/m³ Tournai, 17 April: 27.8 µg/m³, 5.2× its usual 5.3 Tournai, 18 April: 27.7 µg/m³, 5.1× its usual 5.4 Tournai, 19 April: 15.9 µg/m³ Tournai, 20 April: 7.3 µg/m³ Tournai, 21 April: 15.8 µg/m³ Roeselare Roeselare, 14 April: 5.1 µg/m³ Roeselare, 15 April: 9.9 µg/m³ Roeselare, 16 April: 8.0 µg/m³ Roeselare, 17 April: 27.6 µg/m³, 2.9× its usual 9.5 Roeselare, 18 April: 28.7 µg/m³, 3.0× its usual 9.6 Roeselare, 19 April: 19.7 µg/m³ Roeselare, 20 April: 12.7 µg/m³ Roeselare, 21 April: 19.2 µg/m³ Krefeld Krefeld, 14 April: 10.3 µg/m³ Krefeld, 15 April: 10.8 µg/m³ Krefeld, 16 April: 16.6 µg/m³ Krefeld, 17 April: 27.3 µg/m³, 3.1× its usual 8.9 Krefeld, 18 April: 22.3 µg/m³ Krefeld, 19 April: 21.5 µg/m³ Krefeld, 20 April: 20.2 µg/m³ Krefeld, 21 April: 20.8 µg/m³ Andenne Andenne, 14 April: 1.1 µg/m³ Andenne, 15 April: 3.0 µg/m³ Andenne, 16 April: 13.3 µg/m³ Andenne, 17 April: 26.6 µg/m³, 5.0× its usual 5.3 Andenne, 18 April: 20.5 µg/m³ Andenne, 19 April: 14.6 µg/m³ Andenne, 20 April: 7.6 µg/m³ Andenne, 21 April: 10.3 µg/m³ Maldegem Maldegem, 14 April: 4.9 µg/m³ Maldegem, 15 April: 9.7 µg/m³ Maldegem, 16 April: 5.6 µg/m³ Maldegem, 17 April: 26.1 µg/m³, 3.1× its usual 8.4 Maldegem, 18 April: 22.3 µg/m³ Maldegem, 19 April: 15.5 µg/m³ Maldegem, 20 April: 9.8 µg/m³ Maldegem, 21 April: 19.3 µg/m³ Duisburg Duisburg, 14 April: 8.6 µg/m³ Duisburg, 15 April: 12.0 µg/m³ Duisburg, 16 April: 19.4 µg/m³ Duisburg, 17 April: 25.9 µg/m³, 3.2× its usual 8.2 Duisburg, 18 April: 15.5 µg/m³ Duisburg, 19 April: 11.2 µg/m³ Duisburg, 20 April: 11.5 µg/m³ Duisburg, 21 April: 18.1 µg/m³ Gent Gent, 14 April: 4.1 µg/m³ Gent, 15 April: 9.2 µg/m³ Gent, 16 April: 7.7 µg/m³ Gent, 17 April: 25.7 µg/m³, 3.1× its usual 8.3 Gent, 18 April: 23.3 µg/m³ Gent, 19 April: 14.2 µg/m³ Gent, 20 April: 9.8 µg/m³ Gent, 21 April: 14.0 µg/m³ Lille Lille, 14 April: 4.1 µg/m³ Lille, 15 April: 8.3 µg/m³ Lille, 16 April: 6.4 µg/m³ Lille, 17 April: 25.4 µg/m³, 2.8× its usual 9.2 Lille, 18 April: 25.9 µg/m³, 2.8× its usual 9.4 Lille, 19 April: 16.9 µg/m³ Lille, 20 April: 9.9 µg/m³ Lille, 21 April: 16.8 µg/m³ Liège Liège, 14 April: 2.3 µg/m³ Liège, 15 April: 2.9 µg/m³ Liège, 16 April: 13.7 µg/m³ Liège, 17 April: 25.2 µg/m³, 4.3× its usual 5.9 Liège, 18 April: 18.0 µg/m³ Liège, 19 April: 13.8 µg/m³ Liège, 20 April: 7.2 µg/m³ Liège, 21 April: 8.2 µg/m³ Mons Mons, 14 April: 2.0 µg/m³ Mons, 15 April: 5.2 µg/m³ Mons, 16 April: 13.2 µg/m³ Mons, 17 April: 25.2 µg/m³, 3.7× its usual 6.8 Mons, 18 April: 24.4 µg/m³ Mons, 19 April: 14.6 µg/m³ Mons, 20 April: 8.4 µg/m³ Mons, 21 April: 20.4 µg/m³ Beveren Beveren, 14 April: 5.4 µg/m³ Beveren, 15 April: 9.3 µg/m³ Beveren, 16 April: 8.5 µg/m³ Beveren, 17 April: 25.0 µg/m³, 3.0× its usual 8.2 Beveren, 18 April: 22.1 µg/m³ Beveren, 19 April: 14.2 µg/m³ Beveren, 20 April: 10.3 µg/m³ Beveren, 21 April: 17.4 µg/m³ Dreux Dreux, 14 April: 3.4 µg/m³ Dreux, 15 April: 5.5 µg/m³ Dreux, 16 April: 10.4 µg/m³ Dreux, 17 April: 17.7 µg/m³ Dreux, 18 April: 32.8 µg/m³, 4.8× its usual 6.9 Dreux, 19 April: 15.8 µg/m³ Dreux, 20 April: 10.7 µg/m³ Dreux, 21 April: 13.8 µg/m³ Rouen Rouen, 14 April: 6.3 µg/m³ Rouen, 15 April: 8.7 µg/m³ Rouen, 16 April: 12.5 µg/m³ Rouen, 17 April: 16.1 µg/m³ Rouen, 18 April: 32.2 µg/m³, 4.1× its usual 7.9 Rouen, 19 April: 14.0 µg/m³ Rouen, 20 April: 10.4 µg/m³ Rouen, 21 April: 13.3 µg/m³ Beauvais Beauvais, 14 April: 6.4 µg/m³ Beauvais, 15 April: 6.4 µg/m³ Beauvais, 16 April: 10.3 µg/m³ Beauvais, 17 April: 20.5 µg/m³ Beauvais, 18 April: 31.5 µg/m³, 3.5× its usual 8.9 Beauvais, 19 April: 12.5 µg/m³ Beauvais, 20 April: 10.3 µg/m³ Beauvais, 21 April: 12.7 µg/m³ Chartres Chartres, 14 April: 3.6 µg/m³ Chartres, 15 April: 4.2 µg/m³ Chartres, 16 April: 10.4 µg/m³ Chartres, 17 April: 17.0 µg/m³ Chartres, 18 April: 31.0 µg/m³, 4.6× its usual 6.7 Chartres, 19 April: 10.5 µg/m³ Chartres, 20 April: 9.5 µg/m³ Chartres, 21 April: 12.9 µg/m³ Lisieux Lisieux, 14 April: 3.4 µg/m³ Lisieux, 15 April: 7.3 µg/m³ Lisieux, 16 April: 11.9 µg/m³ Lisieux, 17 April: 13.0 µg/m³ Lisieux, 18 April: 30.9 µg/m³, 4.6× its usual 6.7 Lisieux, 19 April: 14.0 µg/m³ Lisieux, 20 April: 9.5 µg/m³ Lisieux, 21 April: 14.3 µg/m³ Le Mans Le Mans, 14 April: 7.6 µg/m³ Le Mans, 15 April: 4.4 µg/m³ Le Mans, 16 April: 12.7 µg/m³ Le Mans, 17 April: 12.7 µg/m³ Le Mans, 18 April: 30.2 µg/m³, 5.4× its usual 5.6 Le Mans, 19 April: 14.1 µg/m³ Le Mans, 20 April: 9.4 µg/m³ Le Mans, 21 April: 15.3 µg/m³ Rambouillet Rambouillet, 14 April: 3.7 µg/m³ Rambouillet, 15 April: 4.6 µg/m³ Rambouillet, 16 April: 10.6 µg/m³ Rambouillet, 17 April: 17.0 µg/m³ Rambouillet, 18 April: 29.8 µg/m³, 4.4× its usual 6.8 Rambouillet, 19 April: 10.4 µg/m³ Rambouillet, 20 April: 10.4 µg/m³ Rambouillet, 21 April: 12.2 µg/m³ Angers Angers, 14 April: 5.2 µg/m³ Angers, 15 April: 3.5 µg/m³ Angers, 16 April: 7.8 µg/m³ Angers, 17 April: 11.4 µg/m³ Angers, 18 April: 29.2 µg/m³, 5.4× its usual 5.4 Angers, 19 April: 16.5 µg/m³ Angers, 20 April: 9.4 µg/m³ Angers, 21 April: 15.3 µg/m³ Évreux Évreux, 14 April: 3.4 µg/m³ Évreux, 15 April: 4.9 µg/m³ Évreux, 16 April: 10.4 µg/m³ Évreux, 17 April: 16.2 µg/m³ Évreux, 18 April: 28.8 µg/m³, 4.4× its usual 6.5 Évreux, 19 April: 11.1 µg/m³ Évreux, 20 April: 10.0 µg/m³ Évreux, 21 April: 13.2 µg/m³ Dieppe Dieppe, 14 April: 8.1 µg/m³ Dieppe, 15 April: 11.2 µg/m³ Dieppe, 16 April: 14.4 µg/m³ Dieppe, 17 April: 21.2 µg/m³ Dieppe, 18 April: 28.8 µg/m³, 3.1× its usual 9.2 Dieppe, 19 April: 16.7 µg/m³ Dieppe, 20 April: 12.5 µg/m³ Dieppe, 21 April: 22.8 µg/m³ Alençon Alençon, 14 April: 3.3 µg/m³ Alençon, 15 April: 4.2 µg/m³ Alençon, 16 April: 9.1 µg/m³ Alençon, 17 April: 10.2 µg/m³ Alençon, 18 April: 28.5 µg/m³, 4.7× its usual 6.1 Alençon, 19 April: 13.4 µg/m³ Alençon, 20 April: 9.2 µg/m³ Alençon, 21 April: 14.4 µg/m³ Paris Paris, 14 April: 6.2 µg/m³ Paris, 15 April: 7.4 µg/m³ Paris, 16 April: 9.6 µg/m³ Paris, 17 April: 18.5 µg/m³ Paris, 18 April: 27.6 µg/m³, 3.1× its usual 8.9 Paris, 19 April: 11.9 µg/m³ Paris, 20 April: 11.1 µg/m³ Paris, 21 April: 14.4 µg/m³ Le Havre Le Havre, 14 April: 3.5 µg/m³ Le Havre, 15 April: 5.4 µg/m³ Le Havre, 16 April: 11.1 µg/m³ Le Havre, 17 April: 15.9 µg/m³ Le Havre, 18 April: 27.5 µg/m³, 3.0× its usual 9.1 Le Havre, 19 April: 15.1 µg/m³ Le Havre, 20 April: 9.9 µg/m³ Le Havre, 21 April: 19.4 µg/m³ Caen Caen, 14 April: 3.3 µg/m³ Caen, 15 April: 4.8 µg/m³ Caen, 16 April: 9.0 µg/m³ Caen, 17 April: 13.9 µg/m³ Caen, 18 April: 27.1 µg/m³, 4.0× its usual 6.7 Caen, 19 April: 17.5 µg/m³ Caen, 20 April: 10.0 µg/m³ Caen, 21 April: 19.4 µg/m³ Rennes Rennes, 14 April: 4.7 µg/m³ Rennes, 15 April: 4.0 µg/m³ Rennes, 16 April: 9.0 µg/m³ Rennes, 17 April: 9.2 µg/m³ Rennes, 18 April: 27.1 µg/m³, 3.7× its usual 7.3 Rennes, 19 April: 16.7 µg/m³ Rennes, 20 April: 9.0 µg/m³ Rennes, 21 April: 13.8 µg/m³ Valenciennes Valenciennes, 14 April: 3.9 µg/m³ Valenciennes, 15 April: 9.1 µg/m³ Valenciennes, 16 April: 7.5 µg/m³ Valenciennes, 17 April: 23.5 µg/m³ Valenciennes, 18 April: 27.1 µg/m³, 2.6× its usual 10.5 Valenciennes, 19 April: 16.4 µg/m³ Valenciennes, 20 April: 11.5 µg/m³ Valenciennes, 21 April: 17.5 µg/m³ Sainte-Geneviève-de… Sainte-Geneviève-des-Bois, 14 April: 11.9 µg/m³ Sainte-Geneviève-des-Bois, 15 April: 10.4 µg/m³ Sainte-Geneviève-des-Bois, 16 April: 11.4 µg/m³ Sainte-Geneviève-des-Bois, 17 April: 20.2 µg/m³ Sainte-Geneviève-des-Bois, 18 April: 26.5 µg/m³, 2.5× its usual 10.7 Sainte-Geneviève-des-Bois, 19 April: 10.2 µg/m³ Sainte-Geneviève-des-Bois, 20 April: 11.9 µg/m³ Sainte-Geneviève-des-Bois, 21 April: 18.1 µg/m³ Saint-Quentin Saint-Quentin, 14 April: 4.5 µg/m³ Saint-Quentin, 15 April: 8.7 µg/m³ Saint-Quentin, 16 April: 8.7 µg/m³ Saint-Quentin, 17 April: 20.4 µg/m³ Saint-Quentin, 18 April: 25.9 µg/m³, 3.0× its usual 8.7 Saint-Quentin, 19 April: 10.4 µg/m³ Saint-Quentin, 20 April: 10.8 µg/m³ Saint-Quentin, 21 April: 13.5 µg/m³ Étampes Étampes, 14 April: 3.2 µg/m³ Étampes, 15 April: 3.7 µg/m³ Étampes, 16 April: 9.8 µg/m³ Étampes, 17 April: 17.4 µg/m³ Étampes, 18 April: 25.6 µg/m³, 4.2× its usual 6.1 Étampes, 19 April: 10.6 µg/m³ Étampes, 20 April: 10.0 µg/m³ Étampes, 21 April: 12.1 µg/m³ Amiens Amiens, 14 April: 4.8 µg/m³ Amiens, 15 April: 6.0 µg/m³ Amiens, 16 April: 9.1 µg/m³ Amiens, 17 April: 19.6 µg/m³ Amiens, 18 April: 25.6 µg/m³, 2.8× its usual 9.0 Amiens, 19 April: 13.5 µg/m³ Amiens, 20 April: 9.3 µg/m³ Amiens, 21 April: 15.2 µg/m³ 14 Apr 15 16 17 18 19 20 21 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. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Le Mans Pays de la Loire, France 1 18 April 5.6 5.4× Angers Pays de la Loire, France 1 18 April 5.4 5.4× Tournai Wallonia, Belgium 2 17 April 5.3 5.2× Andenne Wallonia, Belgium 1 17 April 5.3 5.0× Dreux Centre-Val de Loire, France 1 18 April 6.9 4.8× Alençon Normandy, France 1 18 April 6.1 4.7× Chartres Centre-Val de Loire, France 1 18 April 6.7 4.6× Lisieux Normandy, France 1 18 April 6.7 4.6× Rambouillet Île-de-France, France 1 18 April 6.8 4.4× Évreux Normandy, France 1 18 April 6.5 4.4× Liège Wallonia, Belgium 1 17 April 5.9 4.3× Étampes Île-de-France, France 1 18 April 6.1 4.2× Rouen Normandy, France 1 18 April 7.9 4.1× Caen Normandy, France 1 18 April 6.7 4.0× Kortrijk Flanders, Belgium 2 17 April 8.8 3.7× Rennes Brittany, France 1 18 April 7.3 3.7× Mons Wallonia, Belgium 1 17 April 6.8 3.7× Evergem Flanders, Belgium 2 18 April 9.1 3.5× Beauvais Hauts-de-France, France 1 18 April 8.9 3.5× Menen Flanders, Belgium 2 18 April 9.0 3.2× Duisburg North Rhine-Westphalia, Germany 1 17 April 8.2 3.2× Dieppe Normandy, France 1 18 April 9.2 3.1× Paris Île-de-France, France 1 18 April 8.9 3.1× Krefeld North Rhine-Westphalia, Germany 1 17 April 8.9 3.1× Maldegem Flanders, Belgium 1 17 April 8.4 3.1× Gent Flanders, Belgium 1 17 April 8.3 3.1× Izegem Flanders, Belgium 2 18 April 9.8 3.0× Roeselare Flanders, Belgium 2 18 April 9.6 3.0× Le Havre Normandy, France 1 18 April 9.1 3.0× Saint-Quentin Hauts-de-France, France 1 18 April 8.7 3.0× Beveren Flanders, Belgium 1 17 April 8.2 3.0× Lille Hauts-de-France, France 2 18 April 9.4 2.8× Amiens Hauts-de-France, France 1 18 April 9.0 2.8× Valenciennes Hauts-de-France, France 1 18 April 10.5 2.6× Sainte-Geneviève-des-Bois Île-de-France, France 1 18 April 10.7 2.5× Roubaix Hauts-de-France, France 2 17 April 11.9 2.4×
Daily means in µg/m³, over the days each city counted in this episode. Highest: its highest of those days. Usual: the city's median for the time of year of that day (its days within 21 days of the date, every year, leaving out the week around it). Above usual: its highest day against that, with a usual under 5 µg/m³ taken as 5.
Against other episodes in France and Belgium
Number 16 of 40 episodes in France and Belgium since our records began, by cities reached.
Europe, 28 February to 4 March 2023 279 Europe, December 2025 to January 2026 169 Europe, March 2023 121 Western Europe, January 2024 117 Europe, 14 to 15 January 2025 90 Western Europe, December 2024 75 Spain, France and Portugal, February 2023 72 France, The Netherlands and United Kingdom, January 2023 66 Europe, June 2025 65 Western Europe, January 2025 50 Spain, France and 2 more countries, December 2023 to January 2024 44 France, Belgium and 2 more countries, November and December 2023 43 France, Belgium and Germany, April 2023 36 Bars: cities reached; colour: the level of the episode's highest daily reading. All 40 .
Use this page SmogRank, France, Belgium and Germany, April 2023: 36 cities with PM2.5 at twice their usual or more, 17 to 18 April 2023, smogrank.com/episodes/2023-04-france-belgium-and-germany (accessed 4 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.
