SmogRank / Episodes / United Kingdom

United Kingdom, The Netherlands and Jersey, September 2024

For 2 days, from 19 to 20 September 2024, 13 cities in the United Kingdom, The Netherlands and Jersey had PM2.5 at least twice their usual for the time of year. The worst reading was Canterbury, England, United Kingdom: 33.1 µg/m³ on 20 September, about 5.0× its usual 6.6.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached13in 3 countries
Days219 to 20 September 2024
Worst day20 September9 cities counted
Furthest above usual6.1×Saint Helier

Day by day

20 September 9 cities at twice their usual or more
GillinghamGraysDartfordDagenhamLondonNewmarketNorwichHayesBiggleswadeReadingSouthamptonOxfordRoyal Leamington SpaHillegomTilburgIJsselsteinBirminghamUtrechtEindhovenBristolMedemblikStoke-on-TrentBarneveldHeerlenNijmegenNewportVenrayCardiffNewton AbbotBriton FerryBarnstaplePlymouthEnschedeSaltashBexleyBredaBrightonPortsmouthThe HagueCanvey IslandRotterdamMaarssenAndoverSeafordCanterburyClacton-on-SeaSaint Helier
16 Sep17181920212223
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

Saint HelierSaint Helier, 16 September: 4.1 µg/m³Saint Helier, 17 September: 2.9 µg/m³Saint Helier, 18 September: 17.7 µg/m³Saint Helier, 19 September: 28.7 µg/m³, 5.7× its usual 2.4Saint Helier, 20 September: 30.7 µg/m³, 6.1× its usual 2.5Saint Helier, 21 September: 12.7 µg/m³Saint Helier, 22 September: 14.1 µg/m³Saint Helier, 23 September: no readingMaarssenMaarssen, 16 September: 10.4 µg/m³Maarssen, 17 September: 5.9 µg/m³Maarssen, 18 September: 17.5 µg/m³Maarssen, 19 September: 27.7 µg/m³, 4.9× its usual 5.7Maarssen, 20 September: 22.5 µg/m³Maarssen, 21 September: 17.3 µg/m³Maarssen, 22 September: 16.6 µg/m³Maarssen, 23 September: 10.8 µg/m³The HagueThe Hague, 16 September: 7.4 µg/m³The Hague, 17 September: 5.9 µg/m³The Hague, 18 September: 16.0 µg/m³The Hague, 19 September: 27.5 µg/m³, 4.7× its usual 5.9The Hague, 20 September: 21.9 µg/m³The Hague, 21 September: 20.9 µg/m³The Hague, 22 September: 17.3 µg/m³The Hague, 23 September: 9.4 µg/m³RotterdamRotterdam, 16 September: 5.7 µg/m³Rotterdam, 17 September: 3.2 µg/m³Rotterdam, 18 September: 14.2 µg/m³Rotterdam, 19 September: 26.4 µg/m³, 4.8× its usual 5.5Rotterdam, 20 September: 17.0 µg/m³Rotterdam, 21 September: 16.8 µg/m³Rotterdam, 22 September: 16.4 µg/m³Rotterdam, 23 September: 4.9 µg/m³BredaBreda, 16 September: 11.0 µg/m³Breda, 17 September: 5.1 µg/m³Breda, 18 September: 19.6 µg/m³Breda, 19 September: 25.4 µg/m³, 4.5× its usual 5.7Breda, 20 September: 18.0 µg/m³Breda, 21 September: 19.1 µg/m³Breda, 22 September: 17.5 µg/m³Breda, 23 September: 7.0 µg/m³CanterburyCanterbury, 16 September: 4.9 µg/m³Canterbury, 17 September: 3.9 µg/m³Canterbury, 18 September: 8.6 µg/m³Canterbury, 19 September: 25.1 µg/m³, 3.9× its usual 6.5Canterbury, 20 September: 33.1 µg/m³, 5.0× its usual 6.6Canterbury, 21 September: 24.0 µg/m³Canterbury, 22 September: 25.8 µg/m³Canterbury, 23 September: 10.0 µg/m³Canvey IslandCanvey Island, 16 September: 4.7 µg/m³Canvey Island, 17 September: 4.4 µg/m³Canvey Island, 18 September: 7.3 µg/m³Canvey Island, 19 September: 19.2 µg/m³Canvey Island, 20 September: 28.0 µg/m³, 4.7× its usual 5.9Canvey Island, 21 September: 23.1 µg/m³Canvey Island, 22 September: 24.9 µg/m³Canvey Island, 23 September: 9.0 µg/m³Clacton-on-SeaClacton-on-Sea, 16 September: 4.6 µg/m³Clacton-on-Sea, 17 September: 3.3 µg/m³Clacton-on-Sea, 18 September: 5.5 µg/m³Clacton-on-Sea, 19 September: 17.9 µg/m³Clacton-on-Sea, 20 September: 27.0 µg/m³, 5.2× its usual 5.2Clacton-on-Sea, 21 September: 22.4 µg/m³Clacton-on-Sea, 22 September: 22.9 µg/m³Clacton-on-Sea, 23 September: 11.0 µg/m³PortsmouthPortsmouth, 16 September: 4.2 µg/m³Portsmouth, 17 September: no readingPortsmouth, 18 September: 7.0 µg/m³Portsmouth, 19 September: 19.7 µg/m³Portsmouth, 20 September: 26.1 µg/m³, 4.6× its usual 5.7Portsmouth, 21 September: 21.3 µg/m³Portsmouth, 22 September: 9.8 µg/m³Portsmouth, 23 September: 8.3 µg/m³SeafordSeaford, 16 September: 3.6 µg/m³Seaford, 17 September: 3.2 µg/m³Seaford, 18 September: 6.4 µg/m³Seaford, 19 September: 20.7 µg/m³Seaford, 20 September: 26.0 µg/m³, 5.0× its usual 5.2Seaford, 21 September: 18.1 µg/m³Seaford, 22 September: 9.0 µg/m³Seaford, 23 September: 7.5 µg/m³BexleyBexley, 16 September: 4.4 µg/m³Bexley, 17 September: 3.4 µg/m³Bexley, 18 September: 6.0 µg/m³Bexley, 19 September: 18.7 µg/m³Bexley, 20 September: 26.0 µg/m³, 4.3× its usual 6.0Bexley, 21 September: 22.1 µg/m³Bexley, 22 September: 21.3 µg/m³Bexley, 23 September: 9.8 µg/m³BrightonBrighton, 16 September: 3.5 µg/m³Brighton, 17 September: 3.3 µg/m³Brighton, 18 September: 6.8 µg/m³Brighton, 19 September: 20.4 µg/m³Brighton, 20 September: 25.7 µg/m³, 4.5× its usual 5.7Brighton, 21 September: 18.8 µg/m³Brighton, 22 September: 8.1 µg/m³Brighton, 23 September: 8.3 µg/m³AndoverAndover, 16 September: 4.6 µg/m³Andover, 17 September: 3.8 µg/m³Andover, 18 September: 5.6 µg/m³Andover, 19 September: 16.2 µg/m³Andover, 20 September: 25.2 µg/m³, 5.0× its usual 4.7Andover, 21 September: 19.8 µg/m³Andover, 22 September: 12.0 µg/m³Andover, 23 September: 7.9 µg/m³16 Sep17181920212223
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
Saint HelierSt Helier, Jersey2 30.720 September2.56.1×
Clacton-on-SeaEngland, United Kingdom1 27.020 September5.25.2×
CanterburyEngland, United Kingdom2 33.120 September6.65.0×
SeafordEngland, United Kingdom1 26.020 September5.25.0×
AndoverEngland, United Kingdom1 25.220 September4.75.0×
MaarssenUtrecht, The Netherlands1 27.719 September5.74.9×
RotterdamSouth Holland, The Netherlands1 26.419 September5.54.8×
Canvey IslandEngland, United Kingdom1 28.020 September5.94.7×
The HagueSouth Holland, The Netherlands1 27.519 September5.94.7×
PortsmouthEngland, United Kingdom1 26.120 September5.74.6×
BrightonEngland, United Kingdom1 25.720 September5.74.5×
BredaNorth Brabant, The Netherlands1 25.419 September5.74.5×
BexleyEngland, United Kingdom1 26.020 September6.04.3×

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 The Netherlands

Number 6 of 9 episodes in the United Kingdom and The Netherlands since our records began, by cities reached.

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

Use this page

SmogRank, United Kingdom, The Netherlands and Jersey, September 2024: 13 cities with PM2.5 at twice their usual or more, 19 to 20 September 2024, smogrank.com/episodes/2024-09-united-kingdom-the-netherlands-and-jersey (accessed 4 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.