SmogRank / Episodes / South Korea

South Korea, August 2026

For 1 day, on 20 August 2026, 18 cities in South Korea had PM2.5 at least twice their usual for the time of year. The worst reading was Osan, Gyeonggi-do, South Korea: 39.3 µg/m³ on 20 August, about 3.4× its usual 11.4.

No cause namedWe have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached18in 1 country
Days120 August 2026
Worst day20 August18 cities counted
Furthest above usual3.4×Osan

Day by day

20 August 18 cities at twice their usual or more
GwangjuSeongnam-siIcheon-siAnseongHanamPubalWabuYangp'yŏngNamyangjuHwaseong-siHwadoYeojuCheonanYangjuJungpyongGapyeongSejongTangjinCheongju-siYesanMunsanKoesanWŏnjuHongch’ŏnChuncheonTaesal-liGongjuHongseongSeosanDaejeonCheorwonHwacheonOkcheonBuyeoNonsanBoryeongYŏnmuYangguKinzanMungyeongYeongdongNeietsuSangjuNamsaIksanGunsanYecheonWanjuJeonjuGimcheonJinan-gunYeongjuKimjeBuanGumiChangsuImsilAndongSokchoKosongJeongeupKunwiGangneungJumunjinWaegwanT’aebaekNangenKoch'angDonghae CityHwawŏnDaeguSantyokuJangseongCheongsong gunKuryeGyeongsan-siHayangYeonggwangGwangjuChangnyeongEisenMasanHwasunChinjuHadongNajuKwangyangSuncheonMiryangGwangyangMuanNaesŏGyeongjuYeonilPohangChangwonGoseongMokpoKimhaeYangsanSinanUngsangTongyeongUlsanSinhyeonBusanGijangGeojeAnsan-siGanghwa-gunAsanSuwonIncheonGuri-siChinch'ŏnSeonghwanUijeongbu-siAnyang-siGimpo-siGoyang-siPyeongtaekSeoulGwangmyeongChungjuBucheon-siOsan
17 Aug181920212223
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

OsanOsan, 17 August: 5.8 µg/m³, 0.5× usualOsan, 18 August: 15.0 µg/m³, 1.3× usualOsan, 19 August: 20.7 µg/m³, 1.8× usualOsan, 20 August: 39.3 µg/m³, 3.4× usualOsan, 21 August: 17.3 µg/m³, 1.5× usualOsan, 22 August: 5.6 µg/m³, 0.5× usualOsan, 23 August: 8.0 µg/m³, 0.7× usualGimpo-siGimpo-si, 17 August: 9.0 µg/m³, 0.6× usualGimpo-si, 18 August: 14.5 µg/m³, 1.0× usualGimpo-si, 19 August: 22.4 µg/m³, 1.6× usualGimpo-si, 20 August: 36.4 µg/m³, 2.6× usualGimpo-si, 21 August: 29.5 µg/m³, 2.1× usualGimpo-si, 22 August: 8.6 µg/m³, 0.6× usualGimpo-si, 23 August: 9.1 µg/m³, 0.6× usualPyeongtaekPyeongtaek, 17 August: 6.3 µg/m³, 0.5× usualPyeongtaek, 18 August: 18.8 µg/m³, 1.4× usualPyeongtaek, 19 August: 23.6 µg/m³, 1.8× usualPyeongtaek, 20 August: 34.6 µg/m³, 2.6× usualPyeongtaek, 21 August: 19.9 µg/m³, 1.5× usualPyeongtaek, 22 August: 6.5 µg/m³, 0.5× usualPyeongtaek, 23 August: 8.1 µg/m³, 0.6× usualSeonghwanSeonghwan, 17 August: 10.7 µg/m³, 0.8× usualSeonghwan, 18 August: 21.3 µg/m³, 1.6× usualSeonghwan, 19 August: 21.7 µg/m³, 1.6× usualSeonghwan, 20 August: 34.0 µg/m³, 2.5× usualSeonghwan, 21 August: 16.0 µg/m³, 1.2× usualSeonghwan, 22 August: 11.4 µg/m³, 0.8× usualSeonghwan, 23 August: 12.3 µg/m³, 0.9× usualGwangmyeongGwangmyeong, 17 August: 8.8 µg/m³, 0.7× usualGwangmyeong, 18 August: 15.9 µg/m³, 1.3× usualGwangmyeong, 19 August: 22.3 µg/m³, 1.8× usualGwangmyeong, 20 August: 33.8 µg/m³, 2.7× usualGwangmyeong, 21 August: 22.0 µg/m³, 1.7× usualGwangmyeong, 22 August: 6.5 µg/m³, 0.5× usualGwangmyeong, 23 August: 7.4 µg/m³, 0.6× usualIncheonIncheon, 17 August: 7.6 µg/m³, 0.6× usualIncheon, 18 August: 13.8 µg/m³, 1.0× usualIncheon, 19 August: 21.6 µg/m³, 1.6× usualIncheon, 20 August: 32.0 µg/m³, 2.4× usualIncheon, 21 August: 25.6 µg/m³, 1.9× usualIncheon, 22 August: 7.5 µg/m³, 0.6× usualIncheon, 23 August: 8.4 µg/m³, 0.6× usualChinch'ŏnChinch'ŏn, 17 August: 4.4 µg/m³, 0.4× usualChinch'ŏn, 18 August: 15.5 µg/m³, 1.3× usualChinch'ŏn, 19 August: 17.9 µg/m³, 1.5× usualChinch'ŏn, 20 August: 31.1 µg/m³, 2.5× usualChinch'ŏn, 21 August: 17.8 µg/m³, 1.5× usualChinch'ŏn, 22 August: 8.2 µg/m³, 0.7× usualChinch'ŏn, 23 August: 7.9 µg/m³, 0.6× usualGanghwa-gunGanghwa-gun, 17 August: 10.4 µg/m³, 0.8× usualGanghwa-gun, 18 August: no readingGanghwa-gun, 19 August: 18.8 µg/m³, 1.4× usualGanghwa-gun, 20 August: 30.5 µg/m³, 2.3× usualGanghwa-gun, 21 August: 25.4 µg/m³, 1.9× usualGanghwa-gun, 22 August: 8.4 µg/m³, 0.6× usualGanghwa-gun, 23 August: 7.3 µg/m³, 0.5× usualSeoulSeoul, 17 August: 7.6 µg/m³, 0.6× usualSeoul, 18 August: 15.0 µg/m³, 1.3× usualSeoul, 19 August: 23.0 µg/m³, 1.9× usualSeoul, 20 August: 30.2 µg/m³, 2.6× usualSeoul, 21 August: 19.8 µg/m³, 1.7× usualSeoul, 22 August: 6.8 µg/m³, 0.6× usualSeoul, 23 August: 7.7 µg/m³, 0.7× usualGoyang-siGoyang-si, 17 August: 6.3 µg/m³, 0.5× usualGoyang-si, 18 August: 12.1 µg/m³, 1.1× usualGoyang-si, 19 August: 19.0 µg/m³, 1.7× usualGoyang-si, 20 August: 30.2 µg/m³, 2.6× usualGoyang-si, 21 August: 18.1 µg/m³, 1.6× usualGoyang-si, 22 August: 4.9 µg/m³, 0.4× usualGoyang-si, 23 August: 6.0 µg/m³, 0.5× usualBucheon-siBucheon-si, 17 August: 6.8 µg/m³, 0.6× usualBucheon-si, 18 August: 12.6 µg/m³, 1.2× usualBucheon-si, 19 August: 19.0 µg/m³, 1.8× usualBucheon-si, 20 August: 30.1 µg/m³, 2.8× usualBucheon-si, 21 August: 20.0 µg/m³, 1.9× usualBucheon-si, 22 August: 6.9 µg/m³, 0.6× usualBucheon-si, 23 August: 5.9 µg/m³, 0.5× usualChungjuChungju, 17 August: 3.9 µg/m³, 0.4× usualChungju, 18 August: 16.0 µg/m³, 1.5× usualChungju, 19 August: 19.9 µg/m³, 1.8× usualChungju, 20 August: 29.5 µg/m³, 2.7× usualChungju, 21 August: 17.0 µg/m³, 1.6× usualChungju, 22 August: 10.1 µg/m³, 0.9× usualChungju, 23 August: 10.2 µg/m³, 0.9× usualGuri-siGuri-si, 17 August: 7.3 µg/m³, 0.6× usualGuri-si, 18 August: 12.5 µg/m³, 1.0× usualGuri-si, 19 August: 22.7 µg/m³, 1.9× usualGuri-si, 20 August: 29.4 µg/m³, 2.4× usualGuri-si, 21 August: 19.6 µg/m³, 1.6× usualGuri-si, 22 August: 6.8 µg/m³, 0.6× usualGuri-si, 23 August: 8.5 µg/m³, 0.7× usualAnyang-siAnyang-si, 17 August: 5.9 µg/m³, 0.5× usualAnyang-si, 18 August: 12.6 µg/m³, 1.2× usualAnyang-si, 19 August: 18.8 µg/m³, 1.7× usualAnyang-si, 20 August: 28.6 µg/m³, 2.6× usualAnyang-si, 21 August: 14.8 µg/m³, 1.4× usualAnyang-si, 22 August: 5.2 µg/m³, 0.5× usualAnyang-si, 23 August: 5.0 µg/m³, 0.5× usualAnsan-siAnsan-si, 17 August: 6.4 µg/m³, 0.5× usualAnsan-si, 18 August: 12.3 µg/m³, 1.0× usualAnsan-si, 19 August: 22.5 µg/m³, 1.8× usualAnsan-si, 20 August: 28.2 µg/m³, 2.3× usualAnsan-si, 21 August: 22.6 µg/m³, 1.8× usualAnsan-si, 22 August: 5.0 µg/m³, 0.4× usualAnsan-si, 23 August: 6.5 µg/m³, 0.5× usualSuwonSuwon, 17 August: 6.2 µg/m³, 0.5× usualSuwon, 18 August: 10.8 µg/m³, 0.9× usualSuwon, 19 August: 19.9 µg/m³, 1.7× usualSuwon, 20 August: 27.6 µg/m³, 2.3× usualSuwon, 21 August: 15.6 µg/m³, 1.3× usualSuwon, 22 August: 5.7 µg/m³, 0.5× usualSuwon, 23 August: 6.8 µg/m³, 0.6× usualUijeongbu-siUijeongbu-si, 17 August: 5.2 µg/m³, 0.5× usualUijeongbu-si, 18 August: 11.8 µg/m³, 1.2× usualUijeongbu-si, 19 August: 18.1 µg/m³, 1.8× usualUijeongbu-si, 20 August: 25.4 µg/m³, 2.5× usualUijeongbu-si, 21 August: 18.9 µg/m³, 1.9× usualUijeongbu-si, 22 August: 5.0 µg/m³, 0.5× usualUijeongbu-si, 23 August: 5.8 µg/m³, 0.6× usualAsanAsan, 17 August: 7.0 µg/m³, 0.6× usualAsan, 18 August: 17.4 µg/m³, 1.6× usualAsan, 19 August: 18.8 µg/m³, 1.7× usualAsan, 20 August: 25.1 µg/m³, 2.3× usualAsan, 21 August: 19.3 µg/m³, 1.8× usualAsan, 22 August: 9.8 µg/m³, 0.9× usualAsan, 23 August: 8.7 µg/m³, 0.8× usual17 Aug181920212223
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
OsanGyeonggi-do, South Korea1 39.320 August11.43.4×
Bucheon-siGyeonggi-do, South Korea1 30.120 August10.82.8×
ChungjuNorth Chungcheong, South Korea1 29.520 August10.92.7×
GwangmyeongGyeonggi-do, South Korea1 33.820 August12.72.7×
Anyang-siGyeonggi-do, South Korea1 28.620 August10.82.6×
Goyang-siGyeonggi-do, South Korea1 30.220 August11.52.6×
PyeongtaekGyeonggi-do, South Korea1 34.620 August13.42.6×
Gimpo-siGyeonggi-do, South Korea1 36.420 August14.22.6×
SeoulSeoul, South Korea1 30.220 August11.82.6×
Chinch'ŏnNorth Chungcheong, South Korea1 31.120 August12.22.5×
Uijeongbu-siGyeonggi-do, South Korea1 25.420 August10.02.5×
SeonghwanChungcheongnam-do, South Korea1 34.020 August13.72.5×
Guri-siGyeonggi-do, South Korea1 29.420 August12.02.4×
IncheonIncheon, South Korea1 32.020 August13.52.4×
SuwonGyeonggi-do, South Korea1 27.620 August11.82.3×
AsanChungcheongnam-do, South Korea1 25.120 August10.92.3×
Ansan-siGyeonggi-do, South Korea1 28.220 August12.32.3×
Ganghwa-gunIncheon, South Korea1 30.520 August13.52.3×

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 South Korea

Number 36 of 43 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 43.

Use this page

SmogRank, South Korea, August 2026: 18 cities with PM2.5 at twice their usual or more, 20 August 2026, smogrank.com/episodes/2026-08-south-korea (accessed 3 October 2026).

Download top 10 (PNG)

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.