SmogRank / Episodes / Belgium

Flanders and Wallonia, Belgium, May 2023

For 2 days, from 14 to 15 May 2023, 10 cities in Belgium had PM2.5 at least twice their usual for the time of year. The worst reading was Charleroi, Wallonia, Belgium: 33.2 µg/m³ on 14 May, about 5.7× its usual 5.8.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached10in 1 country
Days214 to 15 May 2023
Worst day14 May8 cities counted
Furthest above usual5.7×Charleroi

Day by day

14 May 8 cities at twice their usual or more
BrusselsZwijndrechtBeverenAntwerpKapellenStabroekLochristiGentEvergemMolBredaWaregemValenciennesTilburgDenainKortrijkRidderkerkMaassluisFlémalle-HauteRotterdamIzegemMarche-en-FamenneRoubaix's-GravenzandeRoeselareThe HagueEindhovenLilleDouaiIJsselsteinSaint-QuentinUtrechtHillegomMaarssenReimsBadhoevedorpHeerlenVelserbroekAmsterdamVelsen-ZuidEupenZaanstadBéthuneKoksijdeAachenVenrayPurmerendÉpernayBarneveldNijmegenVerdunDunkirkJülichEsch-sur-AlzetteMedemblikMönchengladbachLuxembourgJüchenAmiensSaint-DizierKrefeldBergheimThionvilleCoulommiersCreilDüsseldorfMetzCalaisDuisburgTrierRatingenOberhausenKölnBeauvaisLeverkusenSarcellesDomontBorkenEssenBonnSolingenParisNancyMelunGelsenkirchenWuppertalHattingenFontainebleauEnschedeSainte-Geneviève-des-BoisForbachLunévilleSaarbrückenDattelnNeuwiedHagenDortmundÉtampesBendorfKoblenzGroningenSchwerteCanterburyLüdenscheidRambouilletClacton-on-SeaDieppeUnnaLingenMünsterRouenNorwichDreuxBad KreuznachÉvreuxKaiserslauternChartresLimburg an der LahnNetphenCanvey IslandSoestGillinghamWiesbadenOsnabrückMainzWarsteinGraysKehlFriesoytheRüsselsheim am MainWormsNewmarketSeafordDagenhamBexleyEschbornLampertheimLudwigshafen am RheinMannheimGießenSpeyerBielefeldFrankfurt am MainBaden-BadenEggenstein-LeopoldshafenDarmstadtBensheimMarburg an der LahnLe HavreLisieuxKarlsruheBrightonOldenburgLondonMarsbergHeidelbergWieslochPforzheimBiggleswadeGroßostheimHayesDelmenhorstAlençonAschaffenburgRintelnCaenBremenHerrenbergHeilbronnKasselOytenLudwigsburgTübingenStuttgartFilderstadtReutlingenMenenMaldegemWillebroekGrimbergenAarschotMonsLiègeTournaiAndenneCharleroi
11 May12131415161718
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

TournaiTournai, 11 May: 8.4 µg/m³, 1.4× usualTournai, 12 May: 10.6 µg/m³, 1.8× usualTournai, 13 May: 29.8 µg/m³, 5.0× usualTournai, 14 May: 28.1 µg/m³, 4.7× usualTournai, 15 May: 16.5 µg/m³, 2.8× usualTournai, 16 May: 1.5 µg/m³, 0.3× usualTournai, 17 May: 3.5 µg/m³, 0.6× usualTournai, 18 May: 11.2 µg/m³, 1.9× usualCharleroiCharleroi, 11 May: 4.7 µg/m³, 0.8× usualCharleroi, 12 May: 8.6 µg/m³, 1.5× usualCharleroi, 13 May: 13.3 µg/m³, 2.3× usualCharleroi, 14 May: 33.2 µg/m³, 5.7× usualCharleroi, 15 May: 20.9 µg/m³, 3.6× usualCharleroi, 16 May: 2.0 µg/m³, 0.3× usualCharleroi, 17 May: 6.2 µg/m³, 1.1× usualCharleroi, 18 May: 8.9 µg/m³, 1.5× usualMonsMons, 11 May: 6.7 µg/m³, 1.0× usualMons, 12 May: 11.0 µg/m³, 1.6× usualMons, 13 May: 20.3 µg/m³, 3.0× usualMons, 14 May: 31.0 µg/m³, 4.6× usualMons, 15 May: 20.8 µg/m³, 3.1× usualMons, 16 May: 3.2 µg/m³, 0.5× usualMons, 17 May: 7.1 µg/m³, 1.0× usualMons, 18 May: 10.8 µg/m³, 1.6× usualAndenneAndenne, 11 May: 6.9 µg/m³, 1.2× usualAndenne, 12 May: 6.3 µg/m³, 1.1× usualAndenne, 13 May: 14.4 µg/m³, 2.4× usualAndenne, 14 May: 29.7 µg/m³, 5.0× usualAndenne, 15 May: 20.6 µg/m³, 3.5× usualAndenne, 16 May: 1.6 µg/m³, 0.3× usualAndenne, 17 May: 5.3 µg/m³, 0.9× usualAndenne, 18 May: 9.2 µg/m³, 1.6× usualLiègeLiège, 11 May: 10.2 µg/m³, 1.8× usualLiège, 12 May: 6.7 µg/m³, 1.2× usualLiège, 13 May: 13.8 µg/m³, 2.5× usualLiège, 14 May: 26.1 µg/m³, 4.7× usualLiège, 15 May: 24.0 µg/m³, 4.3× usualLiège, 16 May: 2.1 µg/m³, 0.4× usualLiège, 17 May: 7.1 µg/m³, 1.3× usualLiège, 18 May: 8.9 µg/m³, 1.6× usualMenenMenen, 11 May: 11.2 µg/m³, 1.1× usualMenen, 12 May: 13.5 µg/m³, 1.4× usualMenen, 13 May: 24.9 µg/m³, 2.5× usualMenen, 14 May: 25.6 µg/m³, 2.6× usualMenen, 15 May: 20.9 µg/m³, 2.1× usualMenen, 16 May: 5.8 µg/m³, 0.6× usualMenen, 17 May: 7.7 µg/m³, 0.8× usualMenen, 18 May: 12.2 µg/m³, 1.2× usualGrimbergenGrimbergen, 11 May: 10.1 µg/m³, 1.2× usualGrimbergen, 12 May: 8.2 µg/m³, 1.0× usualGrimbergen, 13 May: 14.3 µg/m³, 1.7× usualGrimbergen, 14 May: 25.1 µg/m³, 3.0× usualGrimbergen, 15 May: 27.5 µg/m³, 3.3× usualGrimbergen, 16 May: 5.2 µg/m³, 0.6× usualGrimbergen, 17 May: 7.4 µg/m³, 0.9× usualGrimbergen, 18 May: 9.4 µg/m³, 1.1× usualWillebroekWillebroek, 11 May: 12.5 µg/m³, 1.5× usualWillebroek, 12 May: 8.1 µg/m³, 1.0× usualWillebroek, 13 May: 14.6 µg/m³, 1.8× usualWillebroek, 14 May: 25.0 µg/m³, 3.1× usualWillebroek, 15 May: 26.3 µg/m³, 3.2× usualWillebroek, 16 May: 5.3 µg/m³, 0.7× usualWillebroek, 17 May: 7.1 µg/m³, 0.9× usualWillebroek, 18 May: 8.8 µg/m³, 1.1× usualAarschotAarschot, 11 May: 10.6 µg/m³, 1.4× usualAarschot, 12 May: 7.5 µg/m³, 1.0× usualAarschot, 13 May: 13.4 µg/m³, 1.8× usualAarschot, 14 May: no readingAarschot, 15 May: 26.0 µg/m³, 3.5× usualAarschot, 16 May: 5.1 µg/m³, 0.7× usualAarschot, 17 May: 7.5 µg/m³, 1.0× usualAarschot, 18 May: 9.5 µg/m³, 1.3× usualMaldegemMaldegem, 11 May: 11.1 µg/m³, 1.3× usualMaldegem, 12 May: 14.0 µg/m³, 1.6× usualMaldegem, 13 May: 23.0 µg/m³, 2.7× usualMaldegem, 14 May: 18.6 µg/m³, 2.2× usualMaldegem, 15 May: 25.3 µg/m³, 3.0× usualMaldegem, 16 May: 5.2 µg/m³, 0.6× usualMaldegem, 17 May: 6.8 µg/m³, 0.8× usualMaldegem, 18 May: 9.3 µg/m³, 1.1× usual11 May12131415161718
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
CharleroiWallonia, Belgium1 33.214 May5.85.7×
AndenneWallonia, Belgium1 29.714 May5.95.0×
TournaiWallonia, Belgium1 29.813 May6.05.0×
LiègeWallonia, Belgium1 26.114 May5.64.7×
MonsWallonia, Belgium1 31.014 May6.84.6×
AarschotFlanders, Belgium1 26.015 May7.43.5×
GrimbergenFlanders, Belgium2 27.515 May8.33.3×
WillebroekFlanders, Belgium2 26.315 May8.13.2×
MaldegemFlanders, Belgium1 25.315 May8.53.0×
MenenFlanders, Belgium1 25.614 May9.92.6×

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

Number 7 of 8 episodes in Belgium since our records began, by cities reached.

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

Use this page

SmogRank, Flanders and Wallonia, Belgium, May 2023: 10 cities with PM2.5 at twice their usual or more, 14 to 15 May 2023, smogrank.com/episodes/2023-05-flanders-and-wallonia-belgium (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.