SmogRank / Episodes / South Korea

South Korea, April 2025

For 1 day, on 18 April 2025, 9 cities in South Korea had PM2.5 at least twice their usual for the time of year. The worst reading was Kinzan, Chungcheongnam-do, South Korea: 41.4 µg/m³ on 18 April, about 2.4× its usual 17.1. Ended 18 April.

Few fires were detected near these cities on those days. Spreads like this usually come from still weather trapping smoke from heating, traffic and industry, or from dust.
Cities reached9in 1 country
Days118 April 2025
Worst day18 April9 cities counted
Furthest above usual2.4×Kinzan

Day by day

18 April 9 cities at twice their usual or more
AndongYeongjuYecheonKunwiEisenHayangYeonilPohangMungyeongNeietsuGumiGyeongjuGyeongsan-siSangjuDaeguWaegwanSantyokuHwawŏnPyeongchangGimcheonDonghae CityChungjuMiryangUlsanChangnyeongGangneungKoesanUngsangWŏnjuYangsanJumunjinKimhaeGijangChangwonNaesŏCheongju-siYeojuBusanSintansinHongch’ŏnChinch'ŏnDaejeonPubalChinjuSokchoIcheon-siSejongYangp'yŏngAnseongGoseongSinhyeonChuncheonYangguGeojeCheonanTongyeongGongjuSeonghwanKosongGwangjuGapyeongPyeongtaekNonsanYŏnmuImsilHadongWanjuHwadoAsanHwacheonOsanJeonjuNangenHanamWabuSeongnam-siNamsaNamyangjuKuryeSuwonBuyeoGuri-siGwangyangIksanYesanKwangyangAnyang-siSeoulSuncheonKimjeHwaseong-siUijeongbu-siYeosuAnsan-siYangjuGwangmyeongJeongeupHongseongGunsanTangjinDamyangBucheon-siBoryeongGoyang-siCheorwonBeolgyoBuanIncheonTsushimaGimpo-siHwasunGwangjuSeosanMunsanTaesal-liJangseongKoch'angMasanBoseongGanghwa-gunNajuYeonggwangJangheungYeongamMuanHaenamMokpoNagatoHagiMineSinanMasudaYamaguchiHamadaGōtsuchōŌdachō-ōdaIzumoŌtakeIwakuniUnnanMatsueSakaiminatoYasugichōYonagoNiimiKurayoshiTakahashiKasaokaAsakuchiShimogamoSōjaKurashikiHayashimaTsuyamaOkayamaMarugameZentsujichóTamanoTakinomiyaDodong-riJinan-gunChangsuYeongdongJungpyongYongsan-dongCheongsong gunOkcheonKinzan
15 Apr161718192021
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

KinzanKinzan, 15 April: 19.8 µg/m³Kinzan, 16 April: 24.4 µg/m³Kinzan, 17 April: 27.5 µg/m³Kinzan, 18 April: 41.4 µg/m³, 2.4× its usual 17.1Kinzan, 19 April: 23.8 µg/m³Kinzan, 20 April: 12.0 µg/m³Kinzan, 21 April: 16.3 µg/m³Yongsan-dongYongsan-dong, 15 April: 17.0 µg/m³Yongsan-dong, 16 April: 24.8 µg/m³Yongsan-dong, 17 April: 25.0 µg/m³Yongsan-dong, 18 April: 35.8 µg/m³, 2.1× its usual 17.3Yongsan-dong, 19 April: 19.9 µg/m³Yongsan-dong, 20 April: 13.8 µg/m³Yongsan-dong, 21 April: 12.8 µg/m³JungpyongJungpyong, 15 April: 17.8 µg/m³Jungpyong, 16 April: 22.4 µg/m³Jungpyong, 17 April: 23.1 µg/m³Jungpyong, 18 April: 32.9 µg/m³, 2.1× its usual 16.0Jungpyong, 19 April: 19.9 µg/m³Jungpyong, 20 April: 13.9 µg/m³Jungpyong, 21 April: 8.9 µg/m³YeongdongYeongdong, 15 April: 15.2 µg/m³Yeongdong, 16 April: 20.3 µg/m³Yeongdong, 17 April: 20.6 µg/m³Yeongdong, 18 April: 30.9 µg/m³, 2.1× its usual 14.6Yeongdong, 19 April: 17.0 µg/m³Yeongdong, 20 April: 8.7 µg/m³Yeongdong, 21 April: 9.4 µg/m³OkcheonOkcheon, 15 April: 12.5 µg/m³Okcheon, 16 April: 19.3 µg/m³Okcheon, 17 April: 19.6 µg/m³Okcheon, 18 April: 30.7 µg/m³, 2.3× its usual 13.6Okcheon, 19 April: 17.5 µg/m³Okcheon, 20 April: 5.9 µg/m³Okcheon, 21 April: 7.8 µg/m³ChangsuChangsu, 15 April: 10.6 µg/m³Changsu, 16 April: 18.0 µg/m³Changsu, 17 April: 21.0 µg/m³Changsu, 18 April: 28.8 µg/m³, 2.1× its usual 13.4Changsu, 19 April: 11.6 µg/m³Changsu, 20 April: 7.8 µg/m³Changsu, 21 April: 10.3 µg/m³Cheongsong gunCheongsong gun, 15 April: 10.7 µg/m³Cheongsong gun, 16 April: 18.3 µg/m³Cheongsong gun, 17 April: 19.2 µg/m³Cheongsong gun, 18 April: 27.1 µg/m³, 2.3× its usual 11.9Cheongsong gun, 19 April: 19.5 µg/m³Cheongsong gun, 20 April: 7.0 µg/m³Cheongsong gun, 21 April: 8.7 µg/m³Jinan-gunJinan-gun, 15 April: 11.0 µg/m³Jinan-gun, 16 April: 14.5 µg/m³Jinan-gun, 17 April: 19.2 µg/m³Jinan-gun, 18 April: 27.1 µg/m³, 2.1× its usual 13.0Jinan-gun, 19 April: 10.0 µg/m³Jinan-gun, 20 April: 5.4 µg/m³Jinan-gun, 21 April: 8.8 µg/m³Dodong-riDodong-ri, 15 April: 8.0 µg/m³Dodong-ri, 16 April: 14.6 µg/m³Dodong-ri, 17 April: 20.0 µg/m³Dodong-ri, 18 April: 25.0 µg/m³, 2.0× its usual 12.4Dodong-ri, 19 April: 16.6 µg/m³Dodong-ri, 20 April: 10.7 µg/m³Dodong-ri, 21 April: 10.6 µg/m³15 Apr161718192021
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
KinzanChungcheongnam-do, South Korea1 41.418 April17.12.4×
OkcheonNorth Chungcheong, South Korea1 30.718 April13.62.3×
Cheongsong gunGyeongsangbuk-do, South Korea1 27.118 April11.92.3×
Yongsan-dongSeoul, South Korea1 35.818 April17.32.1×
JungpyongNorth Chungcheong, South Korea1 32.918 April16.02.1×
YeongdongNorth Chungcheong, South Korea1 30.918 April14.62.1×
ChangsuJeollabuk-do, South Korea1 28.818 April13.42.1×
Jinan-gunJeollabuk-do, South Korea1 27.118 April13.02.1×
Dodong-riGyeongsangbuk-do, South Korea1 25.018 April12.42.0×

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 South Korea

Number 62 of 64 episodes in South Korea since our records began, by cities reached.

Bars: cities reached; colour: the level of the episode's highest daily reading. All 64.

Use this page

SmogRank, South Korea, April 2025: 9 cities with PM2.5 at twice their usual or more, 18 April 2025, smogrank.com/episodes/2025-04-south-korea (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. Fire detections from NASA FIRMS; smoke maps from NOAA HMS.