SmogRank / Episodes / United States

Pennsylvania and New Jersey, United States, December 2023

For 1 day, on 25 December 2023, 9 cities in the United States had PM2.5 at least twice their usual for the time of year. The worst reading was Bensalem, Pennsylvania, United States: 38.5 µg/m³ on 25 December, about 4.2× its usual 9.2.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached9in 1 country
Days125 December 2023
Worst day25 December9 cities counted
Furthest above usual4.4×Lexington

Day by day

25 December 9 cities at twice their usual or more
New CityNewburghPatersonFort LeeWhite PlainsJersey CityNew York CityBayonneDanburyNew BrunswickBridgeportEwingTrentonWaterburyNew HavenToms RiverBethlehemAllentownScrantonAlbanyPennsaukenPittsfieldPhiladelphiaHartfordChesterSpringfieldNorth ChicopeePleasantvilleAtlantic CityReadingSouth VinelandWilmingtonGreenfieldNew LondonUticaBearNewarkElktonDoverKeeneCoventryWorcesterSyracuseRutlandEdgewoodYorkProvidencePawtucketHunt ValleyFall RiverBaltimoreLowellBrocktonDerryBostonQuincyScaggsvilleSouth LaurelLynnHaverhillLaconiaRockvilleWashingtonState CollegeRose HillSpringfieldHagerstownPortsmouthRochesterAshburnAltoonaPortlandJohnstownBuffaloKenmoreSt. CatharinesLancasterHarrisburgCarlisleNorristownLebanonLindenElizabethBensalemLexington
22 Dec232425262728
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

BensalemBensalem, 22 December: 12.1 µg/m³, 1.3× usualBensalem, 23 December: 16.5 µg/m³, 1.8× usualBensalem, 24 December: 27.1 µg/m³, 2.9× usualBensalem, 25 December: 38.5 µg/m³, 4.2× usualBensalem, 26 December: 14.2 µg/m³, 1.5× usualBensalem, 27 December: 10.3 µg/m³, 1.1× usualBensalem, 28 December: 6.5 µg/m³, 0.7× usualHarrisburgHarrisburg, 22 December: 9.0 µg/m³, 1.1× usualHarrisburg, 23 December: 13.8 µg/m³, 1.7× usualHarrisburg, 24 December: 21.0 µg/m³, 2.6× usualHarrisburg, 25 December: 28.7 µg/m³, 3.5× usualHarrisburg, 26 December: 22.6 µg/m³, 2.8× usualHarrisburg, 27 December: 14.0 µg/m³, 1.7× usualHarrisburg, 28 December: 6.5 µg/m³, 0.8× usualLebanonLebanon, 22 December: 10.1 µg/m³, 1.3× usualLebanon, 23 December: 15.7 µg/m³, 2.0× usualLebanon, 24 December: 19.5 µg/m³, 2.5× usualLebanon, 25 December: 27.8 µg/m³, 3.6× usualLebanon, 26 December: 22.1 µg/m³, 2.9× usualLebanon, 27 December: 12.3 µg/m³, 1.6× usualLebanon, 28 December: 5.6 µg/m³, 0.7× usualLancasterLancaster, 22 December: 8.3 µg/m³, 1.0× usualLancaster, 23 December: 11.6 µg/m³, 1.4× usualLancaster, 24 December: 15.0 µg/m³, 1.8× usualLancaster, 25 December: 27.0 µg/m³, 3.3× usualLancaster, 26 December: 18.6 µg/m³, 2.3× usualLancaster, 27 December: 10.1 µg/m³, 1.2× usualLancaster, 28 December: 6.6 µg/m³, 0.8× usualCarlisleCarlisle, 22 December: 8.3 µg/m³, 1.1× usualCarlisle, 23 December: 14.6 µg/m³, 1.9× usualCarlisle, 24 December: 20.4 µg/m³, 2.6× usualCarlisle, 25 December: 26.7 µg/m³, 3.5× usualCarlisle, 26 December: 19.9 µg/m³, 2.6× usualCarlisle, 27 December: 11.2 µg/m³, 1.5× usualCarlisle, 28 December: 3.7 µg/m³, 0.5× usualElizabethElizabeth, 22 December: 10.0 µg/m³, 1.6× usualElizabeth, 23 December: 18.5 µg/m³, 2.9× usualElizabeth, 24 December: 21.5 µg/m³, 3.4× usualElizabeth, 25 December: 26.3 µg/m³, 4.1× usualElizabeth, 26 December: 22.0 µg/m³, 3.4× usualElizabeth, 27 December: 17.5 µg/m³, 2.7× usualElizabeth, 28 December: 5.9 µg/m³, 0.9× usualLexingtonLexington, 22 December: 5.4 µg/m³, 0.9× usualLexington, 23 December: 14.8 µg/m³, 2.5× usualLexington, 24 December: 14.8 µg/m³, 2.5× usualLexington, 25 December: 26.1 µg/m³, 4.4× usualLexington, 26 December: 10.1 µg/m³, 1.7× usualLexington, 27 December: 14.1 µg/m³, 2.4× usualLexington, 28 December: 1.1 µg/m³, 0.2× usualLindenLinden, 22 December: 12.1 µg/m³, 1.9× usualLinden, 23 December: 15.8 µg/m³, 2.4× usualLinden, 24 December: 22.7 µg/m³, 3.5× usualLinden, 25 December: 25.3 µg/m³, 3.9× usualLinden, 26 December: 21.5 µg/m³, 3.3× usualLinden, 27 December: 14.8 µg/m³, 2.3× usualLinden, 28 December: 4.7 µg/m³, 0.7× usualNorristownNorristown, 22 December: 6.8 µg/m³, 1.0× usualNorristown, 23 December: 11.5 µg/m³, 1.7× usualNorristown, 24 December: 18.2 µg/m³, 2.6× usualNorristown, 25 December: 25.0 µg/m³, 3.6× usualNorristown, 26 December: 13.0 µg/m³, 1.9× usualNorristown, 27 December: 7.9 µg/m³, 1.1× usualNorristown, 28 December: 2.7 µg/m³, 0.4× usual22 Dec232425262728
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
LexingtonMassachusetts, United States1 26.125 December5.94.4×
BensalemPennsylvania, United States1 38.525 December9.24.2×
ElizabethNew Jersey, United States1 26.325 December6.44.1×
LindenNew Jersey, United States1 25.325 December6.53.9×
NorristownPennsylvania, United States1 25.025 December6.93.6×
LebanonPennsylvania, United States1 27.825 December7.73.6×
HarrisburgPennsylvania, United States1 28.725 December8.13.5×
CarlislePennsylvania, United States1 26.725 December7.73.5×
LancasterPennsylvania, United States1 27.025 December8.23.3×

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 the United States

Number 32 of 41 episodes in the United States since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 41.

Use this page

SmogRank, Pennsylvania and New Jersey, United States, December 2023: 9 cities with PM2.5 at twice their usual or more, 25 December 2023, smogrank.com/episodes/2023-12-pennsylvania-and-new-jersey-united-states (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.