SmogRank / Episodes / United Kingdom
United Kingdom, Belgium and 2 more countries, April 2025
For 2 days, from 12 to 13 April 2025, 24 cities in the United Kingdom, Belgium, The Netherlands and 1 more countries had PM2.5 at least twice their usual for the time of year. The worst reading was Zelzate, Flanders, Belgium: 30.8 µg/m³ on 12 April, about 3.7× its usual 8.3. Ended 13 April.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 24 in 4 countries
Days 2 12 to 13 April 2025
Worst day 12 April 24 cities counted
Furthest above usual 5.3× Halesworth
Day by day
Play 12 April 24 cities at twice their usual or more
Calais Norwich Damme Béthune Maldegem Kortrijk Roubaix Douai Tournai Amiens Denain Valenciennes Maassluis The Hague Spijkenisse Dieppe Beveren Melsele Schiedam Seaford Mons Saint-Quentin Rotterdam Antwerp Kapellen Willebroek Noordwijkerhout Grimbergen Brussels Ridderkerk Brighton Hillegom Mechelen Luton Zaventem Hayes Velsen-Zuid Velserbroek Rouen Rixensart Breda Zwanenburg Badhoevedorp Charleroi Storrington Zaanstad Wormer Amsterdam Lopik Aarschot Breukelen Purmerend IJsselstein Maarssen Tilburg Couvin Utrecht Northampton Mol Namur Kingston upon Hull Champion Le Havre Medemblik Reading Revin Gingelom Scunthorpe Andenne Leicester Hasselt Waalre Houthalen Oxford Eindhoven Portsmouth Hamois Nottingham Barneveld Lunteren Flémalle-Haute Marche-en-Famenne Doncaster Southampton Liège Royal Leamington Spa Andover Bertrix Nijmegen Pickering Derby Chesterfield York Venray Sheffield Barnsley Heerlen Bastogne Birmingham Venlo Habay-la-Vieille Aachen Vielsalm Kaldenkirchen Leeds Nettetal Cannock High Peak Kollum Jülich Westbury Cherbourg Mönchengladbach Titz Jüchen Niederzier Stoke-on-Trent Krefeld Wesel Esch-sur-Alzette Cheadle Hulme Luxembourg Groningen Manchester Duisburg Düsseldorf Borken Bristol Oberhausen Ratingen Pulheim Sinnersdorf Enschede Chepstow Irlam Bottrop Grevenmacher Essen Köln Street Leverkusen Warrington Trier Gelsenkirchen Wigan Wuppertal Hattingen Bonn Newport Speke Preston Datteln Lingen Emden Liverpool Dortmund Norderney Hagen Schwerte Münster Neuwied Lüdenscheid Unna Bendorf Koblenz Höhr-Grenzhausen Friesoythe Newton Abbot Cwmafan Osnabrück Bösel Briton Ferry Soest Bad Kreuznach Limburg an der Lahn Kaiserslautern Wilhelmshaven Oldenburg Barnstaple Warstein Wiesbaden Mainz Worms Dunkirk Izegem Meulebeke Zwijndrecht Menen 's-Gravenzande Sheringham London Veurne Gent Lochristi Koksijde Stabroek Roeselare Zelzate Bexley Canvey Island Hoo Gillingham Brightlingsea Clacton-on-Sea Burwell Newmarket Halesworth 9 Apr 10 11 12 13 14 15 16 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
Zelzate Zelzate, 9 April: 15.9 µg/m³ Zelzate, 10 April: 9.3 µg/m³ Zelzate, 11 April: 17.0 µg/m³ Zelzate, 12 April: 30.8 µg/m³, 3.7× its usual 8.3 Zelzate, 13 April: 12.6 µg/m³ Zelzate, 14 April: 6.5 µg/m³ Zelzate, 15 April: 12.6 µg/m³ Zelzate, 16 April: 5.3 µg/m³ Halesworth Halesworth, 9 April: 4.9 µg/m³ Halesworth, 10 April: 4.4 µg/m³ Halesworth, 11 April: 12.1 µg/m³ Halesworth, 12 April: 30.6 µg/m³, 5.3× its usual 5.8 Halesworth, 13 April: 26.3 µg/m³, 4.5× its usual 5.8 Halesworth, 14 April: 6.2 µg/m³ Halesworth, 15 April: 12.5 µg/m³ Halesworth, 16 April: 10.8 µg/m³ Hoo Hoo, 9 April: 7.8 µg/m³ Hoo, 10 April: 6.3 µg/m³ Hoo, 11 April: 13.3 µg/m³ Hoo, 12 April: 30.5 µg/m³, 4.2× its usual 7.3 Hoo, 13 April: 29.4 µg/m³, 4.0× its usual 7.3 Hoo, 14 April: 6.5 µg/m³ Hoo, 15 April: 14.1 µg/m³ Hoo, 16 April: 9.0 µg/m³ Canvey Island Canvey Island, 9 April: 7.8 µg/m³ Canvey Island, 10 April: 6.3 µg/m³ Canvey Island, 11 April: 13.3 µg/m³ Canvey Island, 12 April: 30.5 µg/m³, 4.2× its usual 7.3 Canvey Island, 13 April: 29.4 µg/m³, 4.0× its usual 7.3 Canvey Island, 14 April: 6.5 µg/m³ Canvey Island, 15 April: 14.1 µg/m³ Canvey Island, 16 April: 9.0 µg/m³ Roeselare Roeselare, 9 April: 16.1 µg/m³ Roeselare, 10 April: 11.1 µg/m³ Roeselare, 11 April: 18.3 µg/m³ Roeselare, 12 April: 30.5 µg/m³, 3.6× its usual 8.5 Roeselare, 13 April: 13.7 µg/m³ Roeselare, 14 April: 7.4 µg/m³ Roeselare, 15 April: 12.0 µg/m³ Roeselare, 16 April: 4.7 µg/m³ Dunkirk Dunkirk, 9 April: 6.3 µg/m³ Dunkirk, 10 April: 6.4 µg/m³ Dunkirk, 11 April: 17.3 µg/m³ Dunkirk, 12 April: 29.3 µg/m³, 2.7× its usual 10.7 Dunkirk, 13 April: 14.6 µg/m³ Dunkirk, 14 April: 8.4 µg/m³ Dunkirk, 15 April: 16.5 µg/m³ Dunkirk, 16 April: 3.9 µg/m³ Lochristi Lochristi, 9 April: 17.9 µg/m³ Lochristi, 10 April: 11.9 µg/m³ Lochristi, 11 April: 19.9 µg/m³ Lochristi, 12 April: 29.2 µg/m³, 3.4× its usual 8.7 Lochristi, 13 April: 13.7 µg/m³ Lochristi, 14 April: 6.3 µg/m³ Lochristi, 15 April: 10.4 µg/m³ Lochristi, 16 April: 5.3 µg/m³ Newmarket Newmarket, 9 April: 9.6 µg/m³ Newmarket, 10 April: 6.2 µg/m³ Newmarket, 11 April: 13.3 µg/m³ Newmarket, 12 April: 29.1 µg/m³, 4.8× its usual 6.1 Newmarket, 13 April: 24.1 µg/m³ Newmarket, 14 April: 6.7 µg/m³ Newmarket, 15 April: 12.3 µg/m³ Newmarket, 16 April: 9.7 µg/m³ Burwell Burwell, 9 April: 9.6 µg/m³ Burwell, 10 April: 6.2 µg/m³ Burwell, 11 April: 13.3 µg/m³ Burwell, 12 April: 29.1 µg/m³, 4.8× its usual 6.1 Burwell, 13 April: 24.1 µg/m³ Burwell, 14 April: 6.7 µg/m³ Burwell, 15 April: 12.3 µg/m³ Burwell, 16 April: 9.7 µg/m³ Clacton-on-Sea Clacton-on-Sea, 9 April: 6.2 µg/m³ Clacton-on-Sea, 10 April: 5.4 µg/m³ Clacton-on-Sea, 11 April: 12.5 µg/m³ Clacton-on-Sea, 12 April: 29.0 µg/m³, 4.6× its usual 6.3 Clacton-on-Sea, 13 April: 27.1 µg/m³, 4.3× its usual 6.3 Clacton-on-Sea, 14 April: 7.2 µg/m³ Clacton-on-Sea, 15 April: 13.7 µg/m³ Clacton-on-Sea, 16 April: 9.7 µg/m³ Brightlingsea Brightlingsea, 9 April: 6.2 µg/m³ Brightlingsea, 10 April: 5.4 µg/m³ Brightlingsea, 11 April: 12.5 µg/m³ Brightlingsea, 12 April: 29.0 µg/m³, 4.6× its usual 6.3 Brightlingsea, 13 April: 27.1 µg/m³, 4.3× its usual 6.3 Brightlingsea, 14 April: 7.2 µg/m³ Brightlingsea, 15 April: 13.7 µg/m³ Brightlingsea, 16 April: 9.7 µg/m³ Bexley Bexley, 9 April: 10.5 µg/m³ Bexley, 10 April: 8.1 µg/m³ Bexley, 11 April: 14.4 µg/m³ Bexley, 12 April: 27.3 µg/m³, 4.0× its usual 6.9 Bexley, 13 April: 22.9 µg/m³ Bexley, 14 April: 7.3 µg/m³ Bexley, 15 April: 11.6 µg/m³ Bexley, 16 April: 6.7 µg/m³ Stabroek Stabroek, 9 April: 13.0 µg/m³ Stabroek, 10 April: 11.8 µg/m³ Stabroek, 11 April: 22.2 µg/m³ Stabroek, 12 April: 27.3 µg/m³, 3.6× its usual 7.6 Stabroek, 13 April: 13.2 µg/m³ Stabroek, 14 April: 5.7 µg/m³ Stabroek, 15 April: 9.2 µg/m³ Stabroek, 16 April: 5.7 µg/m³ Gent Gent, 9 April: 17.4 µg/m³ Gent, 10 April: 11.4 µg/m³ Gent, 11 April: 16.0 µg/m³ Gent, 12 April: 27.1 µg/m³, 3.4× its usual 7.9 Gent, 13 April: 12.1 µg/m³ Gent, 14 April: 5.3 µg/m³ Gent, 15 April: 9.0 µg/m³ Gent, 16 April: 4.3 µg/m³ Gillingham Gillingham, 9 April: 11.5 µg/m³ Gillingham, 10 April: 7.7 µg/m³ Gillingham, 11 April: 10.6 µg/m³ Gillingham, 12 April: 27.0 µg/m³, 4.4× its usual 6.2 Gillingham, 13 April: 19.0 µg/m³ Gillingham, 14 April: 7.0 µg/m³ Gillingham, 15 April: 9.1 µg/m³ Gillingham, 16 April: no reading Koksijde Koksijde, 9 April: 8.3 µg/m³ Koksijde, 10 April: 7.9 µg/m³ Koksijde, 11 April: 15.5 µg/m³ Koksijde, 12 April: 26.7 µg/m³, 3.5× its usual 7.7 Koksijde, 13 April: 12.7 µg/m³ Koksijde, 14 April: 8.1 µg/m³ Koksijde, 15 April: 11.8 µg/m³ Koksijde, 16 April: 3.8 µg/m³ Veurne Veurne, 9 April: 8.3 µg/m³ Veurne, 10 April: 7.9 µg/m³ Veurne, 11 April: 15.5 µg/m³ Veurne, 12 April: 26.7 µg/m³, 3.4× its usual 7.8 Veurne, 13 April: 12.7 µg/m³ Veurne, 14 April: 8.1 µg/m³ Veurne, 15 April: 11.8 µg/m³ Veurne, 16 April: 3.8 µg/m³ Meulebeke Meulebeke, 9 April: 16.4 µg/m³ Meulebeke, 10 April: 10.0 µg/m³ Meulebeke, 11 April: 18.4 µg/m³ Meulebeke, 12 April: 26.7 µg/m³, 2.8× its usual 9.6 Meulebeke, 13 April: 15.3 µg/m³ Meulebeke, 14 April: 6.2 µg/m³ Meulebeke, 15 April: 10.6 µg/m³ Meulebeke, 16 April: 9.3 µg/m³ Izegem Izegem, 9 April: 16.4 µg/m³ Izegem, 10 April: 10.0 µg/m³ Izegem, 11 April: 18.4 µg/m³ Izegem, 12 April: 26.7 µg/m³, 2.8× its usual 9.6 Izegem, 13 April: 15.3 µg/m³ Izegem, 14 April: 6.2 µg/m³ Izegem, 15 April: 10.6 µg/m³ Izegem, 16 April: 9.3 µg/m³ Menen Menen, 9 April: 18.6 µg/m³ Menen, 10 April: 12.0 µg/m³ Menen, 11 April: 20.0 µg/m³ Menen, 12 April: 25.4 µg/m³, 3.0× its usual 8.5 Menen, 13 April: 13.9 µg/m³ Menen, 14 April: 7.8 µg/m³ Menen, 15 April: 13.0 µg/m³ Menen, 16 April: 6.4 µg/m³ Sheringham Sheringham, 9 April: no reading Sheringham, 10 April: 5.4 µg/m³ Sheringham, 11 April: 16.2 µg/m³ Sheringham, 12 April: 25.3 µg/m³, 3.3× its usual 7.6 Sheringham, 13 April: 23.7 µg/m³ Sheringham, 14 April: 5.6 µg/m³ Sheringham, 15 April: 11.3 µg/m³ Sheringham, 16 April: 12.2 µg/m³ London London, 9 April: 8.7 µg/m³ London, 10 April: 9.7 µg/m³ London, 11 April: 16.5 µg/m³ London, 12 April: 25.2 µg/m³, 3.4× its usual 7.4 London, 13 April: 10.6 µg/m³ London, 14 April: 7.0 µg/m³ London, 15 April: 11.5 µg/m³ London, 16 April: 5.0 µg/m³ Zwijndrecht Zwijndrecht, 9 April: 13.7 µg/m³ Zwijndrecht, 10 April: 12.2 µg/m³ Zwijndrecht, 11 April: 19.3 µg/m³ Zwijndrecht, 12 April: 25.2 µg/m³, 3.0× its usual 8.5 Zwijndrecht, 13 April: 11.6 µg/m³ Zwijndrecht, 14 April: 5.7 µg/m³ Zwijndrecht, 15 April: 7.9 µg/m³ Zwijndrecht, 16 April: no reading 's-Gravenzande 's-Gravenzande, 9 April: no reading 's-Gravenzande, 10 April: no reading 's-Gravenzande, 11 April: 14.2 µg/m³ 's-Gravenzande, 12 April: 25.0 µg/m³, 3.3× its usual 7.5 's-Gravenzande, 13 April: 16.9 µg/m³ 's-Gravenzande, 14 April: 8.3 µg/m³ 's-Gravenzande, 15 April: 16.5 µg/m³ 's-Gravenzande, 16 April: 6.0 µg/m³ 9 Apr 10 11 12 13 14 15 16 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
Halesworth England, United Kingdom 2 12 April 5.8 5.3× Newmarket England, United Kingdom 1 12 April 6.1 4.8× Burwell England, United Kingdom 1 12 April 6.1 4.8× Clacton-on-Sea England, United Kingdom 2 12 April 6.3 4.6× Brightlingsea England, United Kingdom 2 12 April 6.3 4.6× Gillingham England, United Kingdom 1 12 April 6.2 4.4× Hoo England, United Kingdom 2 12 April 7.3 4.2× Canvey Island England, United Kingdom 2 12 April 7.3 4.2× Bexley England, United Kingdom 1 12 April 6.9 4.0× Zelzate Flanders, Belgium 1 12 April 8.3 3.7× Roeselare Flanders, Belgium 1 12 April 8.5 3.6× Stabroek Flanders, Belgium 1 12 April 7.6 3.6× Koksijde Flanders, Belgium 1 12 April 7.7 3.5× Lochristi Flanders, Belgium 1 12 April 8.7 3.4× Gent Flanders, Belgium 1 12 April 7.9 3.4× Veurne Flanders, Belgium 1 12 April 7.8 3.4× London England, United Kingdom 1 12 April 7.4 3.4× Sheringham England, United Kingdom 1 12 April 7.6 3.3× '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× Meulebeke Flanders, Belgium 1 12 April 9.6 2.8× 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, 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 the United Kingdom and Belgium
Number 13 of 25 episodes in the United Kingdom and Belgium since our records began, by cities reached.
Europe, January 2025 102 Europe, 12 to 14 December 2024 90 France, The Netherlands and United Kingdom, January 2023 72 Western Europe, January 2025 57 United Kingdom, Belgium and 2 more countries, September 2023 50 France, Belgium and 2 more countries, November and December 2023 49 France, Belgium and Germany, April 2023 43 Europe, May 2023 32 Belgium, The Netherlands and United Kingdom, May 2024 28 Germany, Belgium and 2 more countries, August 2026 27 United Kingdom and The Netherlands, March 2024 27 Belgium, France and 2 more countries, August 2024 25 United Kingdom, Belgium and 2 more countries, April 2025 24 Bars: cities reached; colour: the level of the episode's highest daily reading. All 25 .
Use this page SmogRank, United Kingdom, Belgium and 2 more countries, April 2025: 24 cities with PM2.5 at twice their usual or more, 12 to 13 April 2025, smogrank.com/episodes/2025-04-united-kingdom-belgium-and-2-more-countries (accessed 5 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.
