SmogRank / Episodes / Japan
Japan, May 2024
For 3 days, from 24 to 26 May 2024, 16 cities in Japan had PM2.5 at least twice their usual for the time of year. The worst reading was Chikugo, Fukuoka, Japan: 34.8 µg/m³ on 26 May, about 2.7× its usual 12.8.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 16 in 1 country
Days 3 24 to 26 May 2024
Worst day 25 May 10 cities counted
Furthest above usual 2.9× Kotō
Day by day
Play 25 May 10 cities at twice their usual or more
Saiki Tsukumiura Usuki Tsurusaki Mie Ōita Beppu Nobeoka Kunisaki Yufu Uwajima Yawatahama Hyūga Aso Hikari Yanai Nakatsu Nakamura Kudamatsu Takanabe Buzen Iyo Hita Shūnan Shintomi Hōfu Kikuchi Matsuyama Ube Iwakuni Yukuhashi Ōtake Shinagawa Kanda Miyazaki Onoda Ukiha Yamaguchi Yamaga Tagawa Yame Kure Mine Shimonoseki Kitakyushu Susaki Tamana Iizuka Nōgata Kobayashi Ogōri Hiroshima Imabari Hagi Nakama Tosu Gion Ōmuta Arao Koga Wakasugi Nichinan Nagato Yanagawa Ino Miyakonojō Kasuga Ōyanomachi-noboritate Higashihiroshima Munakata Kanzakimachi-kanzaki Takehara Masuda Fukuoka Koga Kochi Saga Yae Kirishima Mihara Nankoku Higashigō Maebaru-chūō Itoshima Hamada Onomichi Taku Kashima Hondomachi-hondo Isahaya Takeo Ureshinomachi-shimojuku Kanoya Gōtsuchō Aki Ōmura Kan’onjichō Shin’ichi Fukuyama Kagoshima Karatsu Sendai Obita Nagasaki Imarichō-kō Ikedachō Togitsu Kasaoka Kushikino Zentsujichó Marugame Ōdachō-ōda Asakuchi Sasebo Minamikyushu Saikai Matsuura Kaseda-shirakame Takinomiya Iki Kurashiki Unnan Mima Takahashi Sōja Takamatsu Niimi Izumo Tamano Hiragi Yoshinogawa Okayama Shido Kamojimachō-jōgejima Matsue Yasugichō Yonago Tokushima Anan Tsuyama Bizen Narutochō-mitsuishi Tsushima Kariya Kurayoshi Aioi Tatsuno Gotō Ikaruga Sumoto Himeji Gobō Arida Kakogawachō-honmachi Higashinozoe Minato Kainan Akashi Tanabe Ono Gijang Sennan Iwade Busan Nishiwaki Kobe Izumisano Ungsang Kinokawa Kishiwada Geoje Yangsan Tanba Sandachō Izumi Nishinomiya Kimhae Sinhyeon Takarazuka Sakai Amagasaki Hashimoto Kawachi-Nagano Fukuchiyama Sayama Osaka Toyonaka Tondabayashichō Habikino Changwon Tongyeong Yao Higashiosaka Ayabe Yono Kashiwara Takatsuki Shingū Ikoma Naesŏ Hōryūji Hirakata Nantan Kashihara-shi Goseong Kameoka Maizuru Yawata Tenri Nara-shi Kōtari Sugai Kizugawa Jōyō Kumano Uji Kyoto Owase Ōtsu Nabari Chinju Kusatsu Kitahama Ueno-ebisumachi Iga Kōka Yeosu Ōmihachiman Gwangyang Hadong Takashima Youkaichi Kwangyang Hikone Matsusaka Kameyama Suncheon Tsu Nagahama Saikū Ise Beolgyo Suzuka Kurye Yokkaichi Inabe Kuwana Nangen Kaizu Ōgaki Ibi Hashima Mizuho Ama Motosu Ichinomiya Gifu Niihama Saijō Uto Shikokuchūō Tanushimarumachi-toyoki Ōzu Kurume Honmachi Minamata Uekimachi-mōno Chikugo Izumi Kumamoto Hitoyoshi Mifune Kotō 21 May 22 23 24 25 26 27 28 29 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
Chikugo Chikugo, 21 May: 23.0 µg/m³ Chikugo, 22 May: 35.6 µg/m³ Chikugo, 23 May: 25.1 µg/m³ Chikugo, 24 May: 28.8 µg/m³, 2.2× its usual 13.1 Chikugo, 25 May: 17.1 µg/m³ Chikugo, 26 May: 34.8 µg/m³, 2.7× its usual 12.8 Chikugo, 27 May: 6.0 µg/m³ Chikugo, 28 May: 7.3 µg/m³ Chikugo, 29 May: 8.2 µg/m³ Shikokuchūō Shikokuchūō, 21 May: 18.1 µg/m³ Shikokuchūō, 22 May: 24.4 µg/m³ Shikokuchūō, 23 May: 35.5 µg/m³ Shikokuchūō, 24 May: 27.6 µg/m³, 2.4× its usual 11.6 Shikokuchūō, 25 May: 12.1 µg/m³ Shikokuchūō, 26 May: 14.9 µg/m³ Shikokuchūō, 27 May: 17.6 µg/m³ Shikokuchūō, 28 May: 5.0 µg/m³ Shikokuchūō, 29 May: 8.0 µg/m³ Saijō Saijō, 21 May: 19.7 µg/m³ Saijō, 22 May: 21.0 µg/m³ Saijō, 23 May: 27.5 µg/m³ Saijō, 24 May: 27.2 µg/m³, 2.2× its usual 12.4 Saijō, 25 May: 11.9 µg/m³ Saijō, 26 May: 13.6 µg/m³ Saijō, 27 May: 20.2 µg/m³ Saijō, 28 May: 7.0 µg/m³ Saijō, 29 May: 7.3 µg/m³ Tanushimarumachi-to… Tanushimarumachi-toyoki, 21 May: 22.7 µg/m³ Tanushimarumachi-toyoki, 22 May: 31.4 µg/m³ Tanushimarumachi-toyoki, 23 May: 20.8 µg/m³ Tanushimarumachi-toyoki, 24 May: 25.6 µg/m³, 2.2× its usual 11.4 Tanushimarumachi-toyoki, 25 May: 21.5 µg/m³ Tanushimarumachi-toyoki, 26 May: 27.7 µg/m³, 2.5× its usual 11.1 Tanushimarumachi-toyoki, 27 May: 6.6 µg/m³ Tanushimarumachi-toyoki, 28 May: 6.1 µg/m³ Tanushimarumachi-toyoki, 29 May: 9.3 µg/m³ Niihama Niihama, 21 May: 17.4 µg/m³ Niihama, 22 May: 20.2 µg/m³ Niihama, 23 May: 27.9 µg/m³ Niihama, 24 May: 25.6 µg/m³, 2.1× its usual 12.1 Niihama, 25 May: 10.5 µg/m³ Niihama, 26 May: 14.4 µg/m³ Niihama, 27 May: 17.9 µg/m³ Niihama, 28 May: 5.6 µg/m³ Niihama, 29 May: 6.5 µg/m³ Uekimachi-mōno Uekimachi-mōno, 21 May: 22.9 µg/m³ Uekimachi-mōno, 22 May: 28.1 µg/m³ Uekimachi-mōno, 23 May: 9.1 µg/m³ Uekimachi-mōno, 24 May: 19.8 µg/m³ Uekimachi-mōno, 25 May: 29.0 µg/m³, 2.7× its usual 10.6 Uekimachi-mōno, 26 May: 22.9 µg/m³ Uekimachi-mōno, 27 May: no reading Uekimachi-mōno, 28 May: 5.6 µg/m³ Uekimachi-mōno, 29 May: 7.0 µg/m³ Kumamoto Kumamoto, 21 May: 20.5 µg/m³ Kumamoto, 22 May: 23.2 µg/m³ Kumamoto, 23 May: 9.6 µg/m³ Kumamoto, 24 May: 17.5 µg/m³ Kumamoto, 25 May: 28.0 µg/m³, 2.8× its usual 9.9 Kumamoto, 26 May: 22.7 µg/m³ Kumamoto, 27 May: no reading Kumamoto, 28 May: 4.8 µg/m³ Kumamoto, 29 May: 7.2 µg/m³ Minamata Minamata, 21 May: 23.5 µg/m³ Minamata, 22 May: 22.3 µg/m³ Minamata, 23 May: 14.5 µg/m³ Minamata, 24 May: 18.6 µg/m³ Minamata, 25 May: 27.8 µg/m³, 2.6× its usual 10.7 Minamata, 26 May: 18.8 µg/m³ Minamata, 27 May: no reading Minamata, 28 May: 5.4 µg/m³ Minamata, 29 May: 9.7 µg/m³ Kotō Kotō, 21 May: 20.7 µg/m³ Kotō, 22 May: 21.9 µg/m³ Kotō, 23 May: 8.0 µg/m³ Kotō, 24 May: 18.8 µg/m³ Kotō, 25 May: 27.7 µg/m³, 2.7× its usual 10.1 Kotō, 26 May: 29.6 µg/m³, 2.9× its usual 10.1 Kotō, 27 May: no reading Kotō, 28 May: 5.5 µg/m³ Kotō, 29 May: 7.7 µg/m³ Honmachi Honmachi, 21 May: 23.3 µg/m³ Honmachi, 22 May: 29.1 µg/m³ Honmachi, 23 May: 17.5 µg/m³ Honmachi, 24 May: 20.7 µg/m³ Honmachi, 25 May: 27.6 µg/m³, 2.6× its usual 10.8 Honmachi, 26 May: 25.1 µg/m³, 2.3× its usual 10.8 Honmachi, 27 May: no reading Honmachi, 28 May: 6.1 µg/m³ Honmachi, 29 May: 8.3 µg/m³ Ōzu Ōzu, 21 May: 23.8 µg/m³ Ōzu, 22 May: 22.3 µg/m³ Ōzu, 23 May: 6.7 µg/m³ Ōzu, 24 May: 21.0 µg/m³ Ōzu, 25 May: 27.0 µg/m³, 2.6× its usual 10.2 Ōzu, 26 May: 18.2 µg/m³ Ōzu, 27 May: no reading Ōzu, 28 May: 4.6 µg/m³ Ōzu, 29 May: 6.9 µg/m³ Mifune Mifune, 21 May: 23.0 µg/m³ Mifune, 22 May: 20.4 µg/m³ Mifune, 23 May: 6.7 µg/m³ Mifune, 24 May: 14.7 µg/m³ Mifune, 25 May: 26.8 µg/m³, 2.9× its usual 9.1 Mifune, 26 May: 18.9 µg/m³ Mifune, 27 May: no reading Mifune, 28 May: 3.0 µg/m³ Mifune, 29 May: 6.9 µg/m³ Hitoyoshi Hitoyoshi, 21 May: 20.0 µg/m³ Hitoyoshi, 22 May: 22.3 µg/m³ Hitoyoshi, 23 May: 7.5 µg/m³ Hitoyoshi, 24 May: 12.7 µg/m³ Hitoyoshi, 25 May: 26.5 µg/m³, 2.9× its usual 9.1 Hitoyoshi, 26 May: 14.7 µg/m³ Hitoyoshi, 27 May: no reading Hitoyoshi, 28 May: 6.0 µg/m³ Hitoyoshi, 29 May: 9.2 µg/m³ Izumi Izumi, 21 May: 20.9 µg/m³ Izumi, 22 May: 18.6 µg/m³ Izumi, 23 May: 9.3 µg/m³ Izumi, 24 May: 14.7 µg/m³ Izumi, 25 May: 25.7 µg/m³, 2.8× its usual 9.3 Izumi, 26 May: 17.2 µg/m³ Izumi, 27 May: 5.6 µg/m³ Izumi, 28 May: 4.2 µg/m³ Izumi, 29 May: 9.1 µg/m³ Uto Uto, 21 May: 22.7 µg/m³ Uto, 22 May: 24.3 µg/m³ Uto, 23 May: 15.5 µg/m³ Uto, 24 May: 19.6 µg/m³ Uto, 25 May: 25.7 µg/m³, 2.4× its usual 10.6 Uto, 26 May: 23.9 µg/m³ Uto, 27 May: no reading Uto, 28 May: 6.2 µg/m³ Uto, 29 May: 8.6 µg/m³ Kurume Kurume, 21 May: 18.7 µg/m³ Kurume, 22 May: 24.4 µg/m³ Kurume, 23 May: 20.4 µg/m³ Kurume, 24 May: 23.0 µg/m³ Kurume, 25 May: 14.2 µg/m³ Kurume, 26 May: 27.5 µg/m³, 2.6× its usual 10.4 Kurume, 27 May: 5.8 µg/m³ Kurume, 28 May: 6.6 µg/m³ Kurume, 29 May: 7.1 µg/m³ 21 May 22 23 24 25 26 27 28 29 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. Good 0–50
Moderate 51–100
Sensitive groups 101–150
Unhealthy 151–200
Very unhealthy 201–300
Hazardous 301+
Every city it reached
City Days Highest Usual Above usual
Kotō Kumamoto, Japan 2 26 May 10.1 2.9× Mifune Kumamoto, Japan 1 25 May 9.1 2.9× Hitoyoshi Kumamoto, Japan 1 25 May 9.1 2.9× Kumamoto Kumamoto, Japan 1 25 May 9.9 2.8× Izumi Kagoshima, Japan 1 25 May 9.3 2.8× Chikugo Fukuoka, Japan 2 26 May 12.8 2.7× Uekimachi-mōno Kumamoto, Japan 1 25 May 10.6 2.7× Minamata Kumamoto, Japan 1 25 May 10.7 2.6× Honmachi Kumamoto, Japan 2 25 May 10.8 2.6× Kurume Fukuoka, Japan 1 26 May 10.4 2.6× Ōzu Kumamoto, Japan 1 25 May 10.2 2.6× Tanushimarumachi-toyoki Fukuoka, Japan 2 26 May 11.1 2.5× Shikokuchūō Ehime, Japan 1 24 May 11.6 2.4× Uto Kumamoto, Japan 1 25 May 10.6 2.4× Saijō Ehime, Japan 1 24 May 12.4 2.2× Niihama Ehime, Japan 1 24 May 12.1 2.1×
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 Japan
Number 31 of 39 episodes in Japan since our records began, by cities reached.
Japan and South Korea, June and July 2025 508 Japan and South Korea, April 2024 499 Japan and South Korea, March 2025 454 Japan and South Korea, March 2026 305 Japan and South Korea, January 2025 274 Japan and South Korea, February and March 2025 192 Japan, 21 to 25 July 2026 172 Japan, November 2023 131 Japan, 4 to 5 August 2025 126 Japan, January and February 2025 110 Japan, May 2025 103 Japan, March 2025 92 Japan, May 2024 16 Bars: cities reached; colour: the level of the episode's highest daily reading. All 39 .
Use this page SmogRank, Japan, May 2024: 16 cities with PM2.5 at twice their usual or more, 24 to 26 May 2024, smogrank.com/episodes/2024-05-japan (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.
