SmogRank / Episodes / Japan
Japan, 25 to 27 August 2025
For 3 days, from 25 to 27 August 2025, 30 cities in Japan had PM2.5 at least twice their usual for the time of year. The worst reading was Katsuura, Chiba, Japan: 42.0 µg/m³ on 25 August, about 8.4× its usual 5.0.
No cause named We have no fire or smoke records for these days, so we only say what the measurements show.
Cities reached 30 in 1 country
Days 3 25 to 27 August 2025
Worst day 25 August 14 cities counted
Furthest above usual 8.4× Katsuura
Day by day
Play 25 August 14 cities at twice their usual or more
Shinshiro Toyohashi Gamagōri Kosai Okazaki Tahara Toyota Anjō Nishio Chiryū Hamamatsu Hamakita Nisshin Hekinan Kariya Seto Minamichita Handa Tajimi Iwata Toki Tōkai Fukuroi Kaminoma Tokoname Nagoya Kani Kakegawa Inuyama Ama Minokamo Toba Ichinomiya Kakamigahara Iida Kikugawa Kuwana Sekimachi Shimada Yokkaichi Shima Suzuka Ise Kaizu Gifu Hashima Saikū Inabe Fujieda Mizuho Ōgaki Tsu Gero Matsusaka Kameyama Shizuoka Ibi Ina Takayama Kōka Fujinomiya Minami-Alps Iga Ueno-ebisumachi Fuji Okaya Ōmihachiman Suwa Nabari Kofu Ono Kusatsu Matsumoto Owase Numazu Takashima Fujiyoshida Kitahama Susono Tsuruga Ōtsu Izunokuni Shimoda Kizugawa Jōyō Uji Sabae Tenri Sugai Nara-shi Kumano Kyoto Fukui-shi Kashihara-shi Hōryūji Kōtari Saku Kashiwara Yawata Ikoma Ueda Minamiashigara Hirakata Kaga Obama Chikuma Komatsu Tonami Takatsuki Toyama Nonoichi Mikuni Matsutō Kameoka Yao Higashiosaka Shingū Oyabe Tondabayashichō Habikino Kanazawa Hadano Kawachi-Nagano Sayama Hashimoto Imizu Takaoka Tsubata Uozu Yono Nagano Osaka Nantan Toyonaka Sakai Suzaka Hiratsuka Himimachi Chichibu Amagasaki Tomioka Minawa Izumi Nyūzen Aihara Atsugi Ōme Takarazuka Ebina Hachiōji Hakui Nishinomiya Kishiwada Kinokawa Minamirinkan Yamato Hannō Akishima Maizuru Izumisano Machida Kodamachō-kodamaminami Yokota Yorii Morohongō Iruma Itoigawa Sandachō Nanao Iwade Ogawamachi Ayabe Sennan Nakanojō Fuchū Sayama Honjō Kobe Higashimurayama Kodaira Azamino Shibukawa Sakado Tokorozawa Higashikurume Noborito Sakai-nakajima Yokosuka Higashi-Matsuyama Yokohama Kawagoe Kainan Igusa Fukuchiyama Kumagaya Niiza Tanabe Minato Asaka Menuma Tanba Anamizu Numata Jōetsu Gyōda Ōta Akashi Kōnosu Tokyo Nishiwaki Kiryū Ageo Gobō Kyōtango Saitama Hanyū Kawaguchi Ashikaga Kimitsu Kazo Tatebayashi Minamibōsō Higashinozoe Kukichūō Sōka Kisarazu Sumoto Kakogawachō-honmachi Koshigaya Kasukabe Sano Urayasu Minamiuonuma Koga Matsudo Misato, Saitama Toyooka Sodegaura Noda Himeji Bandō Kamagaya Kashiwa Ichihara Narashino Tochigi Oyama Jōsō Chiba Yachiyo Kanuma Toride Tatsuno Yotsukaidō Shimo-tsuma Narutochō-mitsuishi Imaichi Inzai Chikusei Mobara Kaminokawa Sakura Ajiki Utsunomiya Naka Yachimata Mooka Tōgane Narita Tsuchiura Inashiki Ishioka Yaita Yokoshiba Kasama Tottori-shi Yoshinogawa Sawara Sōsa Nasukarasuyama Hiragi Omigawa Hokota Mito Nasushiobara Takamatsu Tsuyama Kashima-shi Hitachiomiya Hitachi-Naka Tamano Okayama Takinomiya Shirakawa Kurayoshi Kurashiki Sōja Hitachi Marugame Zentsujichó Ikedachō Aki Takahashi Asakuchi Kan’onjichō Kitaibaraki Kasaoka Niimi Shikokuchūō Nankoku Fukuyama Iwaki Kochi Yonago Shin’ichi Yasugichō Ino Niihama Sakaiminato Onomichi Saijō Mihara Susaki Matsue Imabari Unnan Takehara Miyoshi Shinagawa Izumo Higashihiroshima Matsuyama Iyo Nakamura Yae Kure Ōdachō-ōda Gion Hiroshima Uwajima Yawatahama Ōtsuki Bizen Mima Nagahama Kariya Hikone Kamisu Aioi Ayase Youkaichi Ikaruga Ono Shido Odawara Chigasaki Miyazu Atami Gotemba Arida Fujisawa Kamakura Kurihama Yamanashi Tokushima Miura Kamojimachō-jōgejima Anan Ōhara Tateyama Katsuura 22 Aug 23 24 25 26 27 28 29 30 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
Katsuura Katsuura, 22 August: 10.0 µg/m³ Katsuura, 23 August: 4.1 µg/m³ Katsuura, 24 August: 19.4 µg/m³ Katsuura, 25 August: 42.0 µg/m³, 8.4× its usual 5.0 Katsuura, 26 August: 13.2 µg/m³ Katsuura, 27 August: 2.7 µg/m³ Katsuura, 28 August: 6.0 µg/m³ Katsuura, 29 August: 6.8 µg/m³ Katsuura, 30 August: 21.0 µg/m³ Ōtsuki Ōtsuki, 22 August: 23.7 µg/m³ Ōtsuki, 23 August: 23.5 µg/m³ Ōtsuki, 24 August: 23.8 µg/m³ Ōtsuki, 25 August: 30.0 µg/m³, 2.7× its usual 11.3 Ōtsuki, 26 August: 28.1 µg/m³, 2.5× its usual 11.3 Ōtsuki, 27 August: 23.4 µg/m³ Ōtsuki, 28 August: 22.0 µg/m³ Ōtsuki, 29 August: 18.6 µg/m³ Ōtsuki, 30 August: 23.5 µg/m³ Ayase Ayase, 22 August: 21.5 µg/m³ Ayase, 23 August: 10.9 µg/m³ Ayase, 24 August: 22.8 µg/m³ Ayase, 25 August: 28.4 µg/m³, 3.3× its usual 8.5 Ayase, 26 August: 19.4 µg/m³ Ayase, 27 August: 12.5 µg/m³ Ayase, 28 August: 10.8 µg/m³ Ayase, 29 August: 13.0 µg/m³ Ayase, 30 August: 23.6 µg/m³ Chigasaki Chigasaki, 22 August: 22.7 µg/m³ Chigasaki, 23 August: 13.4 µg/m³ Chigasaki, 24 August: 21.4 µg/m³ Chigasaki, 25 August: 26.9 µg/m³, 3.6× its usual 7.5 Chigasaki, 26 August: 21.5 µg/m³ Chigasaki, 27 August: 16.0 µg/m³ Chigasaki, 28 August: 11.4 µg/m³ Chigasaki, 29 August: 13.1 µg/m³ Chigasaki, 30 August: 24.5 µg/m³ Miura Miura, 22 August: 8.7 µg/m³ Miura, 23 August: 6.2 µg/m³ Miura, 24 August: 20.7 µg/m³ Miura, 25 August: 26.6 µg/m³, 4.4× its usual 6.1 Miura, 26 August: 14.9 µg/m³ Miura, 27 August: 7.5 µg/m³ Miura, 28 August: 9.8 µg/m³ Miura, 29 August: 12.4 µg/m³ Miura, 30 August: 22.6 µg/m³ Kurihama Kurihama, 22 August: 13.4 µg/m³ Kurihama, 23 August: 6.1 µg/m³ Kurihama, 24 August: 22.0 µg/m³ Kurihama, 25 August: 26.6 µg/m³, 4.2× its usual 6.4 Kurihama, 26 August: 15.3 µg/m³ Kurihama, 27 August: 7.8 µg/m³ Kurihama, 28 August: 11.2 µg/m³ Kurihama, 29 August: 12.5 µg/m³ Kurihama, 30 August: 23.9 µg/m³ Kamakura Kamakura, 22 August: 15.3 µg/m³ Kamakura, 23 August: 6.9 µg/m³ Kamakura, 24 August: 21.5 µg/m³ Kamakura, 25 August: 26.6 µg/m³, 4.1× its usual 6.5 Kamakura, 26 August: 16.3 µg/m³ Kamakura, 27 August: 10.0 µg/m³ Kamakura, 28 August: 10.2 µg/m³ Kamakura, 29 August: 12.1 µg/m³ Kamakura, 30 August: 22.6 µg/m³ Gotemba Gotemba, 22 August: 18.0 µg/m³ Gotemba, 23 August: 7.0 µg/m³ Gotemba, 24 August: 22.4 µg/m³ Gotemba, 25 August: 26.6 µg/m³, 3.7× its usual 7.2 Gotemba, 26 August: 15.9 µg/m³ Gotemba, 27 August: 12.5 µg/m³ Gotemba, 28 August: 10.9 µg/m³ Gotemba, 29 August: 12.1 µg/m³ Gotemba, 30 August: 24.3 µg/m³ Atami Atami, 22 August: 18.5 µg/m³ Atami, 23 August: 9.0 µg/m³ Atami, 24 August: 21.7 µg/m³ Atami, 25 August: 26.6 µg/m³, 3.7× its usual 7.1 Atami, 26 August: 19.2 µg/m³ Atami, 27 August: 12.1 µg/m³ Atami, 28 August: 13.2 µg/m³ Atami, 29 August: 15.9 µg/m³ Atami, 30 August: 22.9 µg/m³ Tateyama Tateyama, 22 August: 10.0 µg/m³ Tateyama, 23 August: 5.1 µg/m³ Tateyama, 24 August: 22.0 µg/m³ Tateyama, 25 August: 26.1 µg/m³, 5.0× its usual 5.2 Tateyama, 26 August: 13.9 µg/m³ Tateyama, 27 August: 4.5 µg/m³ Tateyama, 28 August: 9.5 µg/m³ Tateyama, 29 August: 11.6 µg/m³ Tateyama, 30 August: 19.9 µg/m³ Kamisu Kamisu, 22 August: 14.6 µg/m³ Kamisu, 23 August: 11.3 µg/m³ Kamisu, 24 August: 26.4 µg/m³ Kamisu, 25 August: 26.1 µg/m³, 3.3× its usual 8.0 Kamisu, 26 August: 22.7 µg/m³ Kamisu, 27 August: 8.4 µg/m³ Kamisu, 28 August: 9.4 µg/m³ Kamisu, 29 August: 9.2 µg/m³ Kamisu, 30 August: 29.7 µg/m³ Odawara Odawara, 22 August: 22.1 µg/m³ Odawara, 23 August: 10.3 µg/m³ Odawara, 24 August: 19.9 µg/m³ Odawara, 25 August: 25.8 µg/m³, 3.6× its usual 7.1 Odawara, 26 August: 20.7 µg/m³ Odawara, 27 August: 16.1 µg/m³ Odawara, 28 August: 12.5 µg/m³ Odawara, 29 August: 13.1 µg/m³ Odawara, 30 August: 22.7 µg/m³ Ōhara Ōhara, 22 August: 14.9 µg/m³ Ōhara, 23 August: 5.6 µg/m³ Ōhara, 24 August: 20.4 µg/m³ Ōhara, 25 August: 25.7 µg/m³, 4.9× its usual 5.2 Ōhara, 26 August: 15.8 µg/m³ Ōhara, 27 August: 5.5 µg/m³ Ōhara, 28 August: 7.0 µg/m³ Ōhara, 29 August: 7.8 µg/m³ Ōhara, 30 August: 26.9 µg/m³ Fujisawa Fujisawa, 22 August: 17.3 µg/m³ Fujisawa, 23 August: 8.0 µg/m³ Fujisawa, 24 August: 19.7 µg/m³ Fujisawa, 25 August: 25.2 µg/m³, 4.0× its usual 6.3 Fujisawa, 26 August: 16.6 µg/m³ Fujisawa, 27 August: 10.8 µg/m³ Fujisawa, 28 August: 10.1 µg/m³ Fujisawa, 29 August: 11.9 µg/m³ Fujisawa, 30 August: 21.3 µg/m³ Yamanashi Yamanashi, 22 August: no reading Yamanashi, 23 August: 29.6 µg/m³ Yamanashi, 24 August: no reading Yamanashi, 25 August: no reading Yamanashi, 26 August: 31.6 µg/m³, 4.2× its usual 7.6 Yamanashi, 27 August: no reading Yamanashi, 28 August: no reading Yamanashi, 29 August: no reading Yamanashi, 30 August: no reading Aioi Aioi, 22 August: 8.8 µg/m³ Aioi, 23 August: 11.9 µg/m³ Aioi, 24 August: 19.1 µg/m³ Aioi, 25 August: 17.9 µg/m³ Aioi, 26 August: 26.7 µg/m³, 3.3× its usual 8.1 Aioi, 27 August: 16.8 µg/m³ Aioi, 28 August: 14.0 µg/m³ Aioi, 29 August: 20.5 µg/m³ Aioi, 30 August: 21.5 µg/m³ Hikone Hikone, 22 August: 10.7 µg/m³ Hikone, 23 August: 14.4 µg/m³ Hikone, 24 August: 20.2 µg/m³ Hikone, 25 August: 16.5 µg/m³ Hikone, 26 August: 25.5 µg/m³, 3.3× its usual 7.8 Hikone, 27 August: 14.8 µg/m³ Hikone, 28 August: 9.5 µg/m³ Hikone, 29 August: 21.5 µg/m³ Hikone, 30 August: 13.7 µg/m³ Kariya Kariya, 22 August: 7.7 µg/m³ Kariya, 23 August: 11.0 µg/m³ Kariya, 24 August: 19.2 µg/m³ Kariya, 25 August: 15.9 µg/m³ Kariya, 26 August: 25.5 µg/m³, 3.2× its usual 8.0 Kariya, 27 August: 15.8 µg/m³ Kariya, 28 August: 14.1 µg/m³ Kariya, 29 August: 20.6 µg/m³ Kariya, 30 August: 22.0 µg/m³ Bizen Bizen, 22 August: 11.2 µg/m³ Bizen, 23 August: 13.2 µg/m³ Bizen, 24 August: 18.3 µg/m³ Bizen, 25 August: 16.7 µg/m³ Bizen, 26 August: 25.5 µg/m³, 2.8× its usual 9.2 Bizen, 27 August: 16.3 µg/m³ Bizen, 28 August: 15.6 µg/m³ Bizen, 29 August: 20.4 µg/m³ Bizen, 30 August: 21.3 µg/m³ Ono Ono, 22 August: 5.7 µg/m³ Ono, 23 August: 15.8 µg/m³ Ono, 24 August: 22.5 µg/m³ Ono, 25 August: 22.4 µg/m³ Ono, 26 August: 25.2 µg/m³, 3.4× its usual 7.5 Ono, 27 August: 18.0 µg/m³ Ono, 28 August: 12.2 µg/m³ Ono, 29 August: 20.2 µg/m³ Ono, 30 August: 21.0 µg/m³ Arida Arida, 22 August: 3.3 µg/m³ Arida, 23 August: 17.9 µg/m³ Arida, 24 August: 21.7 µg/m³ Arida, 25 August: 20.0 µg/m³ Arida, 26 August: 25.1 µg/m³, 4.0× its usual 6.3 Arida, 27 August: 13.2 µg/m³ Arida, 28 August: 24.2 µg/m³ Arida, 29 August: 22.9 µg/m³ Arida, 30 August: 15.8 µg/m³ Ikaruga Ikaruga, 22 August: 8.8 µg/m³ Ikaruga, 23 August: 13.4 µg/m³ Ikaruga, 24 August: 17.9 µg/m³ Ikaruga, 25 August: 17.8 µg/m³ Ikaruga, 26 August: 25.1 µg/m³, 3.4× its usual 7.3 Ikaruga, 27 August: 17.7 µg/m³ Ikaruga, 28 August: 12.3 µg/m³ Ikaruga, 29 August: 19.0 µg/m³ Ikaruga, 30 August: 20.5 µg/m³ Miyazu Miyazu, 22 August: 12.5 µg/m³ Miyazu, 23 August: 10.7 µg/m³ Miyazu, 24 August: 13.9 µg/m³ Miyazu, 25 August: 10.8 µg/m³ Miyazu, 26 August: 25.0 µg/m³, 3.7× its usual 6.7 Miyazu, 27 August: 14.0 µg/m³ Miyazu, 28 August: 6.3 µg/m³ Miyazu, 29 August: 15.8 µg/m³ Miyazu, 30 August: 13.8 µg/m³ Youkaichi Youkaichi, 22 August: 8.3 µg/m³ Youkaichi, 23 August: 13.5 µg/m³ Youkaichi, 24 August: 20.2 µg/m³ Youkaichi, 25 August: 17.9 µg/m³ Youkaichi, 26 August: 25.0 µg/m³, 3.4× its usual 7.4 Youkaichi, 27 August: 16.5 µg/m³ Youkaichi, 28 August: 9.1 µg/m³ Youkaichi, 29 August: 20.6 µg/m³ Youkaichi, 30 August: 14.7 µg/m³ Nagahama Nagahama, 22 August: 12.1 µg/m³ Nagahama, 23 August: 13.5 µg/m³ Nagahama, 24 August: 21.5 µg/m³ Nagahama, 25 August: 18.2 µg/m³ Nagahama, 26 August: 25.0 µg/m³, 3.0× its usual 8.3 Nagahama, 27 August: 15.1 µg/m³ Nagahama, 28 August: 10.4 µg/m³ Nagahama, 29 August: 21.9 µg/m³ Nagahama, 30 August: 15.2 µg/m³ Anan Anan, 22 August: 7.5 µg/m³ Anan, 23 August: 17.5 µg/m³ Anan, 24 August: 21.2 µg/m³ Anan, 25 August: 24.7 µg/m³ Anan, 26 August: 24.4 µg/m³ Anan, 27 August: 33.5 µg/m³, 4.6× its usual 7.3 Anan, 28 August: 21.6 µg/m³ Anan, 29 August: 22.4 µg/m³ Anan, 30 August: 24.6 µg/m³ Kamojimachō-jōgejima Kamojimachō-jōgejima, 22 August: 6.6 µg/m³ Kamojimachō-jōgejima, 23 August: 10.7 µg/m³ Kamojimachō-jōgejima, 24 August: 17.2 µg/m³ Kamojimachō-jōgejima, 25 August: 19.9 µg/m³ Kamojimachō-jōgejima, 26 August: 21.5 µg/m³ Kamojimachō-jōgejima, 27 August: 30.7 µg/m³, 4.6× its usual 6.7 Kamojimachō-jōgejima, 28 August: 14.2 µg/m³ Kamojimachō-jōgejima, 29 August: 20.4 µg/m³ Kamojimachō-jōgejima, 30 August: 23.9 µg/m³ Tokushima Tokushima, 22 August: 5.2 µg/m³ Tokushima, 23 August: 11.5 µg/m³ Tokushima, 24 August: 16.0 µg/m³ Tokushima, 25 August: 15.6 µg/m³ Tokushima, 26 August: 19.0 µg/m³ Tokushima, 27 August: 26.8 µg/m³, 4.3× its usual 6.2 Tokushima, 28 August: 15.9 µg/m³ Tokushima, 29 August: 16.4 µg/m³ Tokushima, 30 August: 18.7 µg/m³ Shido Shido, 22 August: 6.9 µg/m³ Shido, 23 August: 13.7 µg/m³ Shido, 24 August: 19.4 µg/m³ Shido, 25 August: 20.0 µg/m³ Shido, 26 August: 20.8 µg/m³ Shido, 27 August: 25.9 µg/m³, 3.5× its usual 7.4 Shido, 28 August: 16.7 µg/m³ Shido, 29 August: 15.7 µg/m³ Shido, 30 August: 19.2 µg/m³ Mima Mima, 22 August: 7.7 µg/m³ Mima, 23 August: 11.3 µg/m³ Mima, 24 August: 16.2 µg/m³ Mima, 25 August: 17.7 µg/m³ Mima, 26 August: 18.9 µg/m³ Mima, 27 August: 25.9 µg/m³, 2.9× its usual 8.9 Mima, 28 August: 14.5 µg/m³ Mima, 29 August: 16.0 µg/m³ Mima, 30 August: 22.3 µg/m³ 22 Aug 23 24 25 26 27 28 29 30 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
Katsuura Chiba, Japan 1 25 August 5.0 8.4× Tateyama Chiba, Japan 1 25 August 5.2 5.0× Ōhara Chiba, Japan 1 25 August 5.2 4.9× Anan Tokushima, Japan 1 27 August 7.3 4.6× Kamojimachō-jōgejima Tokushima, Japan 1 27 August 6.7 4.6× Miura Kanagawa, Japan 1 25 August 6.1 4.4× Tokushima Tokushima, Japan 1 27 August 6.2 4.3× Yamanashi Yamanashi, Japan 1 26 August 7.6 4.2× Kurihama Kanagawa, Japan 1 25 August 6.4 4.2× Kamakura Kanagawa, Japan 1 25 August 6.5 4.1× Fujisawa Kanagawa, Japan 1 25 August 6.3 4.0× Arida Wakayama, Japan 1 26 August 6.3 4.0× Gotemba Shizuoka, Japan 1 25 August 7.2 3.7× Atami Shizuoka, Japan 1 25 August 7.1 3.7× Miyazu Kyoto, Japan 1 26 August 6.7 3.7× Chigasaki Kanagawa, Japan 1 25 August 7.5 3.6× Odawara Kanagawa, Japan 1 25 August 7.1 3.6× Shido Kagawa, Japan 1 27 August 7.4 3.5× Ono Hyōgo, Japan 1 26 August 7.5 3.4× Ikaruga Hyōgo, Japan 1 26 August 7.3 3.4× Youkaichi Shiga, Japan 1 26 August 7.4 3.4× Ayase Kanagawa, Japan 1 25 August 8.5 3.3× Aioi Hyōgo, Japan 1 26 August 8.1 3.3× Kamisu Ibaraki, Japan 1 25 August 8.0 3.3× Hikone Shiga, Japan 1 26 August 7.8 3.3× Kariya Hyōgo, Japan 1 26 August 8.0 3.2× Nagahama Shiga, Japan 1 26 August 8.3 3.0× Mima Tokushima, Japan 1 27 August 8.9 2.9× Bizen Okayama, Japan 1 26 August 9.2 2.8× Ōtsuki Yamanashi, Japan 2 25 August 11.3 2.7×
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 23 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, 25 to 27 August 2025 30 Bars: cities reached; colour: the level of the episode's highest daily reading. All 39 .
Use this page SmogRank, Japan, 25 to 27 August 2025: 30 cities with PM2.5 at twice their usual or more, 25 to 27 August 2025, smogrank.com/episodes/2025-08-25-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.
