SmogRank / Episodes / Belgium

Belgium and France, April 2023

For 1 day, on 5 April 2023, 9 cities in Belgium, France and The Netherlands had PM2.5 at least twice their usual for the time of year. The worst reading was Roeselare, Flanders, Belgium: 30.6 µg/m³ on 5 April, about 3.6× its usual 8.6.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached9in 3 countries
Days15 April 2023
Worst day5 April9 cities counted
Furthest above usual3.8×'s-Gravenzande

Day by day

5 April 9 cities at twice their usual or more
GentLochristiBeverenZwijndrechtTournaiStabroekWillebroekAntwerpKapellenBrusselsMaassluisMonsValenciennesKoksijdeThe HagueRotterdamRidderkerkBredaCharleroiBéthuneAarschotHillegomTilburgSaint-QuentinMolVelsen-ZuidBadhoevedorpIJsselsteinMaarssenZaanstadAmsterdamUtrechtAndenneCalaisPurmerendEindhovenAmiensFlémalle-HauteLiègeMedemblikReimsBarneveldNijmegenÉpernayVenrayHeerlenBeauvaisClacton-on-SeaEupenCanterburyAachenNorwichJülichVerdunMönchengladbachDieppeJüchenKrefeldEsch-sur-AlzetteCanvey IslandLuxembourgBergheimRouenDuisburgDüsseldorfThionvilleRatingenOberhausenGraysBorkenNewmarketKölnÉvreuxMetzLeverkusenEssenEnschedeTrierDagenhamBexleySolingenGelsenkirchenGroningenBonnWuppertalSeafordHattingenLondonDattelnBrightonDortmundForbachLe HavreSchwerteSaarbrückenLisieuxLüdenscheidHayesMünsterBendorfKoblenzSoestCaenNetphenLimburg an der LahnOsnabrückFriesoytheKingston upon HullWilhelmshavenRoubaixIzegemKortrijkEvergemMaldegemMenenLilleRoeselare's-Gravenzande
2 Apr345678
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

RoeselareRoeselare, 2 April: 15.3 µg/m³, 1.8× usualRoeselare, 3 April: 12.0 µg/m³, 1.4× usualRoeselare, 4 April: 10.8 µg/m³, 1.3× usualRoeselare, 5 April: 30.6 µg/m³, 3.6× usualRoeselare, 6 April: 15.7 µg/m³, 1.8× usualRoeselare, 7 April: 7.8 µg/m³, 0.9× usualRoeselare, 8 April: 14.9 µg/m³, 1.7× usualIzegemIzegem, 2 April: 14.8 µg/m³, 1.5× usualIzegem, 3 April: 12.0 µg/m³, 1.2× usualIzegem, 4 April: 10.5 µg/m³, 1.1× usualIzegem, 5 April: 30.3 µg/m³, 3.1× usualIzegem, 6 April: 20.4 µg/m³, 2.1× usualIzegem, 7 April: 8.2 µg/m³, 0.8× usualIzegem, 8 April: 15.6 µg/m³, 1.6× usualRoubaixRoubaix, 2 April: 13.3 µg/m³, 1.3× usualRoubaix, 3 April: 16.6 µg/m³, 1.6× usualRoubaix, 4 April: 12.5 µg/m³, 1.2× usualRoubaix, 5 April: 29.8 µg/m³, 2.9× usualRoubaix, 6 April: 16.2 µg/m³, 1.6× usualRoubaix, 7 April: 8.0 µg/m³, 0.8× usualRoubaix, 8 April: 15.0 µg/m³, 1.5× usualEvergemEvergem, 2 April: 14.2 µg/m³, 1.6× usualEvergem, 3 April: 8.8 µg/m³, 1.0× usualEvergem, 4 April: 10.6 µg/m³, 1.2× usualEvergem, 5 April: 28.9 µg/m³, 3.2× usualEvergem, 6 April: 18.4 µg/m³, 2.1× usualEvergem, 7 April: 6.6 µg/m³, 0.7× usualEvergem, 8 April: 17.9 µg/m³, 2.0× usualMenenMenen, 2 April: 16.0 µg/m³, 1.8× usualMenen, 3 April: 12.8 µg/m³, 1.4× usualMenen, 4 April: 10.6 µg/m³, 1.2× usualMenen, 5 April: 28.8 µg/m³, 3.2× usualMenen, 6 April: 16.5 µg/m³, 1.9× usualMenen, 7 April: 7.3 µg/m³, 0.8× usualMenen, 8 April: 14.6 µg/m³, 1.6× usual's-Gravenzande's-Gravenzande, 2 April: 5.5 µg/m³, 0.7× usual's-Gravenzande, 3 April: 2.6 µg/m³, 0.4× usual's-Gravenzande, 4 April: 6.9 µg/m³, 0.9× usual's-Gravenzande, 5 April: 28.2 µg/m³, 3.8× usual's-Gravenzande, 6 April: no reading's-Gravenzande, 7 April: 4.9 µg/m³, 0.7× usual's-Gravenzande, 8 April: 18.5 µg/m³, 2.5× usualMaldegemMaldegem, 2 April: 11.1 µg/m³, 1.3× usualMaldegem, 3 April: 6.4 µg/m³, 0.8× usualMaldegem, 4 April: 9.3 µg/m³, 1.1× usualMaldegem, 5 April: 27.0 µg/m³, 3.2× usualMaldegem, 6 April: 17.2 µg/m³, 2.0× usualMaldegem, 7 April: 5.2 µg/m³, 0.6× usualMaldegem, 8 April: 13.8 µg/m³, 1.6× usualLilleLille, 2 April: 11.2 µg/m³, 1.4× usualLille, 3 April: 14.2 µg/m³, 1.8× usualLille, 4 April: 10.1 µg/m³, 1.3× usualLille, 5 April: 25.7 µg/m³, 3.3× usualLille, 6 April: 14.0 µg/m³, 1.8× usualLille, 7 April: 6.7 µg/m³, 0.8× usualLille, 8 April: 11.8 µg/m³, 1.5× usualKortrijkKortrijk, 2 April: 16.2 µg/m³, 2.0× usualKortrijk, 3 April: 13.1 µg/m³, 1.6× usualKortrijk, 4 April: 10.5 µg/m³, 1.3× usualKortrijk, 5 April: 25.6 µg/m³, 3.1× usualKortrijk, 6 April: 15.9 µg/m³, 1.9× usualKortrijk, 7 April: 9.0 µg/m³, 1.1× usualKortrijk, 8 April: 15.0 µg/m³, 1.8× usual2 Apr345678
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
's-GravenzandeSouth Holland, The Netherlands1 28.25 April7.43.8×
RoeselareFlanders, Belgium1 30.65 April8.63.6×
LilleHauts-de-France, France1 25.75 April7.93.3×
EvergemFlanders, Belgium1 28.95 April8.93.2×
MenenFlanders, Belgium1 28.85 April8.93.2×
MaldegemFlanders, Belgium1 27.05 April8.43.2×
KortrijkFlanders, Belgium1 25.65 April8.23.1×
IzegemFlanders, Belgium1 30.35 April9.93.1×
RoubaixHauts-de-France, France1 29.85 April10.32.9×

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 13 of 17 episodes in Belgium and France since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 17.

Use this page

SmogRank, Belgium and France, April 2023: 9 cities with PM2.5 at twice their usual or more, 5 April 2023, smogrank.com/episodes/2023-04-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.