SmogRank / Episodes / Belgium
Belgium and France, August 2023
For 1 day, on 18 August 2023, 15 cities in Belgium and France had PM2.5 at least twice their usual for the time of year. The worst reading was Roeselare, Flanders, Belgium: 31.7 µg/m³ on 18 August, about 5.2× its usual 6.1.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 15 in 2 countries
Days 1 18 August 2023
Worst day 18 August 15 cities counted
Furthest above usual 5.5× Tournai
Day by day
Play 18 August 15 cities at twice their usual or more
Gent Lochristi Mons Denain Brussels Grimbergen Beveren Willebroek Zwijndrecht Douai Antwerp Charleroi Stabroek Kapellen Saint-Quentin Béthune Breda Rotterdam Andenne Ridderkerk The Hague Reims Tilburg Marche-en-Famenne Amiens Flémalle-Haute Hillegom Épernay IJsselstein Liège Eindhoven Badhoevedorp Velserbroek Utrecht Calais Velsen-Zuid Amsterdam Creil Zaanstad Coulommiers Purmerend Heerlen Sarcelles Domont Barneveld Eupen Verdun Venray Nijmegen Paris Medemblik Saint-Dizier Melun Sainte-Geneviève-des-Bois Esch-sur-Alzette Fontainebleau Luxembourg Canterbury Clacton-on-Sea Thionville Dieppe Étampes Rambouillet Metz Rouen Louviers Norwich Évreux Dreux Nancy Chartres Canvey Island Gillingham Enschede Lunéville Forbach Seaford Newmarket Bexley Dagenham Groningen Le Havre Lisieux Brighton London Lingen Biggleswade Hayes Alençon Caen Osnabrück Friesoythe Reading Portsmouth Oldenburg Oxford Southampton Andover Nottingham Delmenhorst Großostheim Royal Leamington Spa Rinteln Bremen Oyten Roubaix Valenciennes Izegem Menen Evergem Waregem Dunkirk Kortrijk Mol Koksijde Lille Maldegem Roeselare Aarschot Tournai 15 Aug 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
Roeselare Roeselare, 15 August: 5.6 µg/m³, 0.9× usual Roeselare, 16 August: 9.1 µg/m³, 1.5× usual Roeselare, 17 August: 15.7 µg/m³, 2.6× usual Roeselare, 18 August: 31.7 µg/m³, 5.2× usual Roeselare, 19 August: 9.5 µg/m³, 1.6× usual Roeselare, 20 August: 5.5 µg/m³, 0.9× usual Roeselare, 21 August: 12.1 µg/m³, 2.0× usual Maldegem Maldegem, 15 August: 5.9 µg/m³, 1.0× usual Maldegem, 16 August: 9.0 µg/m³, 1.5× usual Maldegem, 17 August: 10.8 µg/m³, 1.8× usual Maldegem, 18 August: 30.6 µg/m³, 5.1× usual Maldegem, 19 August: 11.1 µg/m³, 1.8× usual Maldegem, 20 August: 5.3 µg/m³, 0.9× usual Maldegem, 21 August: 9.2 µg/m³, 1.5× usual Dunkirk Dunkirk, 15 August: 5.0 µg/m³, 0.8× usual Dunkirk, 16 August: 7.0 µg/m³, 1.1× usual Dunkirk, 17 August: 8.4 µg/m³, 1.3× usual Dunkirk, 18 August: 30.4 µg/m³, 4.6× usual Dunkirk, 19 August: 11.1 µg/m³, 1.7× usual Dunkirk, 20 August: 5.9 µg/m³, 0.9× usual Dunkirk, 21 August: 8.2 µg/m³, 1.2× usual Evergem Evergem, 15 August: 6.2 µg/m³, 0.9× usual Evergem, 16 August: 10.9 µg/m³, 1.6× usual Evergem, 17 August: 13.2 µg/m³, 1.9× usual Evergem, 18 August: 29.9 µg/m³, 4.4× usual Evergem, 19 August: 11.3 µg/m³, 1.7× usual Evergem, 20 August: 5.8 µg/m³, 0.9× usual Evergem, 21 August: 9.2 µg/m³, 1.4× usual Waregem Waregem, 15 August: 5.7 µg/m³, 0.9× usual Waregem, 16 August: 9.9 µg/m³, 1.5× usual Waregem, 17 August: 13.8 µg/m³, 2.1× usual Waregem, 18 August: 28.9 µg/m³, 4.4× usual Waregem, 19 August: 9.0 µg/m³, 1.4× usual Waregem, 20 August: 5.6 µg/m³, 0.8× usual Waregem, 21 August: 12.3 µg/m³, 1.9× usual Koksijde Koksijde, 15 August: 4.7 µg/m³, 0.8× usual Koksijde, 16 August: 8.3 µg/m³, 1.5× usual Koksijde, 17 August: 8.8 µg/m³, 1.5× usual Koksijde, 18 August: 28.5 µg/m³, 5.0× usual Koksijde, 19 August: 7.1 µg/m³, 1.2× usual Koksijde, 20 August: 5.3 µg/m³, 0.9× usual Koksijde, 21 August: 7.8 µg/m³, 1.4× usual Aarschot Aarschot, 15 August: 5.2 µg/m³, 1.0× usual Aarschot, 16 August: 7.1 µg/m³, 1.4× usual Aarschot, 17 August: 11.9 µg/m³, 2.3× usual Aarschot, 18 August: 28.0 µg/m³, 5.5× usual Aarschot, 19 August: 10.0 µg/m³, 2.0× usual Aarschot, 20 August: 5.0 µg/m³, 1.0× usual Aarschot, 21 August: 5.8 µg/m³, 1.1× usual Tournai Tournai, 15 August: 2.0 µg/m³, 0.4× usual Tournai, 16 August: 7.4 µg/m³, 1.5× usual Tournai, 17 August: 13.3 µg/m³, 2.7× usual Tournai, 18 August: 27.6 µg/m³, 5.5× usual Tournai, 19 August: 6.5 µg/m³, 1.3× usual Tournai, 20 August: 2.0 µg/m³, 0.4× usual Tournai, 21 August: 4.7 µg/m³, 0.9× usual Kortrijk Kortrijk, 15 August: 4.6 µg/m³, 0.8× usual Kortrijk, 16 August: 9.5 µg/m³, 1.6× usual Kortrijk, 17 August: 14.1 µg/m³, 2.4× usual Kortrijk, 18 August: 27.3 µg/m³, 4.6× usual Kortrijk, 19 August: 7.7 µg/m³, 1.3× usual Kortrijk, 20 August: 5.3 µg/m³, 0.9× usual Kortrijk, 21 August: 10.1 µg/m³, 1.7× usual Izegem Izegem, 15 August: 5.6 µg/m³, 0.8× usual Izegem, 16 August: 9.3 µg/m³, 1.3× usual Izegem, 17 August: 13.3 µg/m³, 1.9× usual Izegem, 18 August: 27.1 µg/m³, 3.9× usual Izegem, 19 August: 12.5 µg/m³, 1.8× usual Izegem, 20 August: 5.5 µg/m³, 0.8× usual Izegem, 21 August: 10.9 µg/m³, 1.6× usual Mol Mol, 15 August: 5.3 µg/m³, 0.9× usual Mol, 16 August: 6.7 µg/m³, 1.2× usual Mol, 17 August: 10.2 µg/m³, 1.8× usual Mol, 18 August: 26.0 µg/m³, 4.6× usual Mol, 19 August: 12.2 µg/m³, 2.2× usual Mol, 20 August: 5.0 µg/m³, 0.9× usual Mol, 21 August: 5.7 µg/m³, 1.0× usual Valenciennes Valenciennes, 15 August: 6.6 µg/m³, 1.0× usual Valenciennes, 16 August: 9.8 µg/m³, 1.5× usual Valenciennes, 17 August: 13.5 µg/m³, 2.0× usual Valenciennes, 18 August: 26.0 µg/m³, 3.9× usual Valenciennes, 19 August: 10.7 µg/m³, 1.6× usual Valenciennes, 20 August: 7.9 µg/m³, 1.2× usual Valenciennes, 21 August: no reading Lille Lille, 15 August: 4.9 µg/m³, 1.0× usual Lille, 16 August: 9.1 µg/m³, 1.8× usual Lille, 17 August: 11.8 µg/m³, 2.3× usual Lille, 18 August: 25.9 µg/m³, 5.1× usual Lille, 19 August: 10.1 µg/m³, 2.0× usual Lille, 20 August: 6.8 µg/m³, 1.3× usual Lille, 21 August: 5.6 µg/m³, 1.1× usual Menen Menen, 15 August: 4.5 µg/m³, 0.8× usual Menen, 16 August: 8.6 µg/m³, 1.4× usual Menen, 17 August: 14.6 µg/m³, 2.4× usual Menen, 18 August: 25.2 µg/m³, 4.2× usual Menen, 19 August: 7.7 µg/m³, 1.3× usual Menen, 20 August: 5.4 µg/m³, 0.9× usual Menen, 21 August: 8.0 µg/m³, 1.3× usual Roubaix Roubaix, 15 August: 6.1 µg/m³, 0.9× usual Roubaix, 16 August: 9.3 µg/m³, 1.4× usual Roubaix, 17 August: 12.5 µg/m³, 1.9× usual Roubaix, 18 August: 25.1 µg/m³, 3.9× usual Roubaix, 19 August: 10.2 µg/m³, 1.6× usual Roubaix, 20 August: 6.6 µg/m³, 1.0× usual Roubaix, 21 August: 6.6 µg/m³, 1.0× usual 15 Aug 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
Tournai Wallonia, Belgium 1 18 August 3.6 5.5× Aarschot Flanders, Belgium 1 18 August 5.1 5.5× Roeselare Flanders, Belgium 1 18 August 6.1 5.2× Maldegem Flanders, Belgium 1 18 August 6.0 5.1× Lille Hauts-de-France, France 1 18 August 5.1 5.1× Koksijde Flanders, Belgium 1 18 August 5.7 5.0× Mol Flanders, Belgium 1 18 August 5.6 4.6× Kortrijk Flanders, Belgium 1 18 August 5.9 4.6× Dunkirk Hauts-de-France, France 1 18 August 6.6 4.6× Evergem Flanders, Belgium 1 18 August 6.8 4.4× Waregem Flanders, Belgium 1 18 August 6.6 4.4× Menen Flanders, Belgium 1 18 August 6.0 4.2× Valenciennes Hauts-de-France, France 1 18 August 6.6 3.9× Izegem Flanders, Belgium 1 18 August 6.9 3.9× Roubaix Hauts-de-France, France 1 18 August 6.5 3.9×
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 Belgium and France
Number 10 of 17 episodes in Belgium and France since our records began, by cities reached.
Central Europe, February and March 2023 274 Western Europe, March 2023 119 Southern Europe, December 2023 97 North-eastern Spain and France, February 2023 72 France, The Netherlands and United Kingdom, January 2023 66 France, Belgium and United Kingdom, November and December 2023 43 United Kingdom and Belgium, September 2023 42 France and Belgium, April 2023 36 Belgium and Germany, May 2023 26 Belgium and France, August 2023 15 United Kingdom, Belgium and France, June 2023 10 Flanders and Wallonia, Belgium, May 2023 10 Bars: cities reached; colour: the level of the episode's highest daily reading. All 17 .
Use this page SmogRank, Belgium and France, August 2023: 15 cities with PM2.5 at twice their usual or more, 18 August 2023, smogrank.com/episodes/2023-08-belgium-and-france (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.
