SmogRank / Episodes / Belgium
Belgium and United Kingdom, April 2025
For 1 day, on 12 April 2025, 16 cities in Belgium, the United Kingdom, The Netherlands and 1 more countries had PM2.5 at least twice their usual for the time of year. The worst reading was Evergem, Flanders, Belgium: 30.8 µg/m³ on 12 April, about 3.5× its usual 8.8.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 16 in 4 countries
Days 1 12 April 2025
Worst day 12 April 16 cities counted
Furthest above usual 4.8× Newmarket
Day by day
Play 12 April 16 cities at twice their usual or more
Calais Béthune Kortrijk Roubaix Norwich Maldegem Douai Tournai Amiens Denain Valenciennes Dieppe Saint-Quentin Seaford Mons Beveren Maassluis Spijkenisse The Hague Stabroek Creil Willebroek Rouen Antwerp Schiedam Kapellen Brighton Brussels Grimbergen Rotterdam Mechelen Zaventem Louviers Hayes Ridderkerk Luton Rixensart Charleroi Hillegom Breda Velsen-Zuid Velserbroek Aarschot Badhoevedorp Le Havre Zaanstad Amsterdam Namur Reims IJsselstein Tilburg Maarssen Purmerend Mol Northampton Reading Utrecht Andenne Medemblik Portsmouth Hasselt Kingston upon Hull Houthalen Oxford Eindhoven Caen Leicester Flémalle-Haute Marche-en-Famenne Barneveld Nottingham Southampton Liège Andover Royal Leamington Spa Nijmegen Doncaster Derby Venray Chesterfield Heerlen York Sheffield Aachen Venlo Birmingham Barnsley Cherbourg Cannock Westbury Leeds Jülich Mönchengladbach High Peak Esch-sur-Alzette Jüchen Krefeld Luxembourg Wesel Stoke-on-Trent Thionville Duisburg Cheadle Hulme Düsseldorf Bristol Metz Pulheim Ratingen Manchester Oberhausen Borken Groningen Saint Helier Bottrop Enschede Trier Köln Leverkusen Essen Irlam Gelsenkirchen Warrington Wuppertal Bonn Hattingen Newport Dillingen Wigan Saint-Avold Datteln Speke Völklingen Preston Lingen Dortmund Hagen Saarbrücken Liverpool Emden Schwerte Neuwied Lüdenscheid Münster Bendorf Unna Koblenz Newton Abbot Briton Ferry Friesoythe Osnabrück Soest Bad Kreuznach Kaiserslautern Limburg an der Lahn Barnstaple Wiesbaden Oldenburg Wilhelmshaven Mainz Dunkirk Izegem Menen Zwijndrecht 's-Gravenzande Gent Lochristi London Evergem Koksijde Roeselare Bexley Canvey Island Gillingham Clacton-on-Sea Newmarket 9 Apr 10 11 12 13 14 15 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
Evergem Evergem, 9 April: 15.9 µg/m³, 1.8× usual Evergem, 10 April: 9.1 µg/m³, 1.0× usual Evergem, 11 April: 15.8 µg/m³, 1.8× usual Evergem, 12 April: 30.8 µg/m³, 3.5× usual Evergem, 13 April: 12.0 µg/m³, 1.4× usual Evergem, 14 April: 6.5 µg/m³, 0.7× usual Evergem, 15 April: 14.7 µg/m³, 1.7× usual Canvey Island Canvey Island, 9 April: 7.8 µg/m³, 1.1× usual Canvey Island, 10 April: 6.3 µg/m³, 0.9× usual Canvey Island, 11 April: 13.3 µg/m³, 1.8× usual Canvey Island, 12 April: 30.5 µg/m³, 4.2× usual Canvey Island, 13 April: 29.4 µg/m³, 4.0× usual Canvey Island, 14 April: 6.5 µg/m³, 0.9× usual Canvey Island, 15 April: 14.1 µg/m³, 1.9× usual Roeselare Roeselare, 9 April: 16.1 µg/m³, 1.9× usual Roeselare, 10 April: 11.1 µg/m³, 1.3× usual Roeselare, 11 April: 18.3 µg/m³, 2.2× usual Roeselare, 12 April: 30.5 µg/m³, 3.6× usual Roeselare, 13 April: 13.7 µg/m³, 1.6× usual Roeselare, 14 April: 7.4 µg/m³, 0.9× usual Roeselare, 15 April: 12.0 µg/m³, 1.4× usual Dunkirk Dunkirk, 9 April: 6.3 µg/m³, 0.6× usual Dunkirk, 10 April: 6.4 µg/m³, 0.6× usual Dunkirk, 11 April: 17.3 µg/m³, 1.6× usual Dunkirk, 12 April: 29.3 µg/m³, 2.7× usual Dunkirk, 13 April: 14.6 µg/m³, 1.4× usual Dunkirk, 14 April: 8.4 µg/m³, 0.8× usual Dunkirk, 15 April: 16.5 µg/m³, 1.5× usual Lochristi Lochristi, 9 April: 17.9 µg/m³, 2.1× usual Lochristi, 10 April: 11.9 µg/m³, 1.4× usual Lochristi, 11 April: 19.9 µg/m³, 2.3× usual Lochristi, 12 April: 29.2 µg/m³, 3.4× usual Lochristi, 13 April: 13.7 µg/m³, 1.6× usual Lochristi, 14 April: 6.3 µg/m³, 0.7× usual Lochristi, 15 April: 10.4 µg/m³, 1.2× usual Newmarket Newmarket, 9 April: 9.6 µg/m³, 1.6× usual Newmarket, 10 April: 6.2 µg/m³, 1.0× usual Newmarket, 11 April: 13.3 µg/m³, 2.2× usual Newmarket, 12 April: 29.1 µg/m³, 4.8× usual Newmarket, 13 April: 24.1 µg/m³, 4.0× usual Newmarket, 14 April: 6.7 µg/m³, 1.1× usual Newmarket, 15 April: 12.3 µg/m³, 2.0× usual Clacton-on-Sea Clacton-on-Sea, 9 April: 6.2 µg/m³, 1.0× usual Clacton-on-Sea, 10 April: 5.4 µg/m³, 0.9× usual Clacton-on-Sea, 11 April: 12.5 µg/m³, 2.0× usual Clacton-on-Sea, 12 April: 29.0 µg/m³, 4.6× usual Clacton-on-Sea, 13 April: 27.1 µg/m³, 4.3× usual Clacton-on-Sea, 14 April: 7.2 µg/m³, 1.1× usual Clacton-on-Sea, 15 April: 13.7 µg/m³, 2.2× usual Bexley Bexley, 9 April: 10.5 µg/m³, 1.5× usual Bexley, 10 April: 8.1 µg/m³, 1.2× usual Bexley, 11 April: 14.4 µg/m³, 2.1× usual Bexley, 12 April: 27.3 µg/m³, 4.0× usual Bexley, 13 April: 22.9 µg/m³, 3.3× usual Bexley, 14 April: 7.3 µg/m³, 1.1× usual Bexley, 15 April: 11.6 µg/m³, 1.7× usual Gent Gent, 9 April: 17.4 µg/m³, 2.2× usual Gent, 10 April: 11.4 µg/m³, 1.4× usual Gent, 11 April: 16.0 µg/m³, 2.0× usual Gent, 12 April: 27.1 µg/m³, 3.4× usual Gent, 13 April: 12.1 µg/m³, 1.5× usual Gent, 14 April: 5.3 µg/m³, 0.7× usual Gent, 15 April: 9.0 µg/m³, 1.1× usual Gillingham Gillingham, 9 April: 11.5 µg/m³, 1.9× usual Gillingham, 10 April: 7.7 µg/m³, 1.2× usual Gillingham, 11 April: 10.6 µg/m³, 1.7× usual Gillingham, 12 April: 27.0 µg/m³, 4.4× usual Gillingham, 13 April: 19.0 µg/m³, 3.1× usual Gillingham, 14 April: 7.0 µg/m³, 1.1× usual Gillingham, 15 April: 9.1 µg/m³, 1.5× usual Koksijde Koksijde, 9 April: 8.3 µg/m³, 1.1× usual Koksijde, 10 April: 7.9 µg/m³, 1.0× usual Koksijde, 11 April: 15.5 µg/m³, 2.0× usual Koksijde, 12 April: 26.7 µg/m³, 3.5× usual Koksijde, 13 April: 12.7 µg/m³, 1.6× usual Koksijde, 14 April: 8.1 µg/m³, 1.1× usual Koksijde, 15 April: 11.8 µg/m³, 1.5× usual Izegem Izegem, 9 April: 16.4 µg/m³, 1.7× usual Izegem, 10 April: 10.0 µg/m³, 1.0× usual Izegem, 11 April: 18.4 µg/m³, 1.9× usual Izegem, 12 April: 26.7 µg/m³, 2.8× usual Izegem, 13 April: 15.3 µg/m³, 1.6× usual Izegem, 14 April: 6.2 µg/m³, 0.6× usual Izegem, 15 April: 10.6 µg/m³, 1.1× usual Menen Menen, 9 April: 18.6 µg/m³, 2.2× usual Menen, 10 April: 12.0 µg/m³, 1.4× usual Menen, 11 April: 20.0 µg/m³, 2.4× usual Menen, 12 April: 25.4 µg/m³, 3.0× usual Menen, 13 April: 13.9 µg/m³, 1.6× usual Menen, 14 April: 7.8 µg/m³, 0.9× usual Menen, 15 April: 13.0 µg/m³, 1.5× usual London London, 9 April: 8.7 µg/m³, 1.2× usual London, 10 April: 9.7 µg/m³, 1.3× usual London, 11 April: 16.5 µg/m³, 2.2× usual London, 12 April: 25.2 µg/m³, 3.4× usual London, 13 April: 10.6 µg/m³, 1.4× usual London, 14 April: 7.0 µg/m³, 0.9× usual London, 15 April: 11.5 µg/m³, 1.6× usual Zwijndrecht Zwijndrecht, 9 April: 13.7 µg/m³, 1.6× usual Zwijndrecht, 10 April: 12.2 µg/m³, 1.4× usual Zwijndrecht, 11 April: 19.3 µg/m³, 2.3× usual Zwijndrecht, 12 April: 25.2 µg/m³, 3.0× usual Zwijndrecht, 13 April: 11.6 µg/m³, 1.4× usual Zwijndrecht, 14 April: 5.7 µg/m³, 0.7× usual Zwijndrecht, 15 April: 7.9 µg/m³, 0.9× usual 's-Gravenzande 's-Gravenzande, 9 April: no reading 's-Gravenzande, 10 April: no reading 's-Gravenzande, 11 April: 14.2 µg/m³, 1.9× usual 's-Gravenzande, 12 April: 25.0 µg/m³, 3.3× usual 's-Gravenzande, 13 April: 16.9 µg/m³, 2.3× usual 's-Gravenzande, 14 April: 8.3 µg/m³, 1.1× usual 's-Gravenzande, 15 April: 16.5 µg/m³, 2.2× usual 9 Apr 10 11 12 13 14 15 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
Newmarket England, United Kingdom 1 12 April 6.1 4.8× Clacton-on-Sea England, United Kingdom 1 12 April 6.3 4.6× Gillingham England, United Kingdom 1 12 April 6.2 4.4× Canvey Island England, United Kingdom 1 12 April 7.3 4.2× Bexley England, United Kingdom 1 12 April 6.9 4.0× Roeselare Flanders, Belgium 1 12 April 8.5 3.6× Evergem Flanders, Belgium 1 12 April 8.8 3.5× Koksijde Flanders, Belgium 1 12 April 7.7 3.5× Gent Flanders, Belgium 1 12 April 7.9 3.4× London England, United Kingdom 1 12 April 7.4 3.4× Lochristi Flanders, Belgium 1 12 April 8.7 3.4× 's-Gravenzande South Holland, The Netherlands 1 12 April 7.5 3.3× Menen Flanders, Belgium 1 12 April 8.5 3.0× Zwijndrecht Flanders, Belgium 1 12 April 8.5 3.0× Izegem Flanders, Belgium 1 12 April 9.6 2.8× Dunkirk Hauts-de-France, France 1 12 April 10.7 2.7×
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 the United Kingdom
Number 7 of 15 episodes in Belgium and the United Kingdom since our records began, by cities reached.
France, The Netherlands and United Kingdom, January 2023 66 Western Europe, January 2025 50 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 United Kingdom, April 2025 16 Belgium and France, August 2023 15 France and Belgium, June 2026 13 Belgium and France, October 2025 10 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 15 .
Use this page SmogRank, Belgium and United Kingdom, April 2025: 16 cities with PM2.5 at twice their usual or more, 12 April 2025, smogrank.com/episodes/2025-04-belgium-and-united-kingdom (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.
