Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021
The severe aerosol pollution in East Asia has been a focus of much research. In Japan, the environmental quality standard (EQS) for PM _2.5 was established in 2009 (daily average, 35 μ g m ^−3 ; annual average, 15 μ g m ^−3 ), and its achievement rate was below 50% during the early 2010s. Then, the...
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| Format: | Article |
| Language: | English |
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IOP Publishing
2024-01-01
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| Series: | Environmental Research Letters |
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| Online Access: | https://doi.org/10.1088/1748-9326/ad37ce |
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| author | Syuichi Itahashi Itsushi Uno |
| author_facet | Syuichi Itahashi Itsushi Uno |
| author_sort | Syuichi Itahashi |
| collection | DOAJ |
| description | The severe aerosol pollution in East Asia has been a focus of much research. In Japan, the environmental quality standard (EQS) for PM _2.5 was established in 2009 (daily average, 35 μ g m ^−3 ; annual average, 15 μ g m ^−3 ), and its achievement rate was below 50% during the early 2010s. Then, the PM _2.5 concentration gradually decreased, the achievement rate improved, and the EQS for PM _2.5 was finally achieved (100%) in fiscal year (FY) 2021. Because transboundary aerosol pollution is an important factor in Japanese air quality, here we analysed the long-term dataset of the satellite-measured fine-mode aerosol optical depth (AOD _f ) over the East Asian ocean to reveal the changes in the transboundary aerosol over East Asia. Overall, a decrease in AOD _f was seen over the entire East Asian ocean during the period analysed. A gradual declining trend in AOD _f was measured (−4% to −5%/year over the adjacent ocean around Japan) and corresponded well to the trend in PM _2.5 concentration observed in Japan (−5.3%/year) during FY2010–FY2021. Due to the domestic contribution in Japan, the negative trend was slightly greater for Japanese PM _2.5 concentration than for AOD _f over the adjacent ocean around Japan, and we concluded that the main reason for the dramatic air quality improvement in PM _2.5 in Japan was driven by the improvement of transboundary aerosol pollution over East Asia. In addition, the 12 year analysis period (FY2010 to FY2021) was divided into three parts: stagnation (FY2010 to FY2014), in which PM _2.5 and AOD _f remained the same as they were in FY2010; improvement (FY2015 to FY2018), in which PM _2.5 and AOD _f declined dramatically; and achievement (FY2019 to FY2021), in which PM _2.5 and AOD _f declined further. |
| first_indexed | 2024-04-24T11:50:14Z |
| format | Article |
| id | doaj.art-80424249c85a4869a6d7de0f10c88d95 |
| institution | Directory Open Access Journal |
| issn | 1748-9326 |
| language | English |
| last_indexed | 2024-04-24T11:50:14Z |
| publishDate | 2024-01-01 |
| publisher | IOP Publishing |
| record_format | Article |
| series | Environmental Research Letters |
| spelling | doaj.art-80424249c85a4869a6d7de0f10c88d952024-04-09T07:47:45ZengIOP PublishingEnvironmental Research Letters1748-93262024-01-0119404406510.1088/1748-9326/ad37ceDramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021Syuichi Itahashi0https://orcid.org/0000-0001-7567-7831Itsushi Uno1Sustainable System Research Laboratory (SSRL), Central Research Institute of Electric Power Industry (CRIEPI) , Abiko, Chiba, JapanResearch Institute for Applied Mechanics (RIAM), Kyushu University , Kasuga, Fukuoka, JapanThe severe aerosol pollution in East Asia has been a focus of much research. In Japan, the environmental quality standard (EQS) for PM _2.5 was established in 2009 (daily average, 35 μ g m ^−3 ; annual average, 15 μ g m ^−3 ), and its achievement rate was below 50% during the early 2010s. Then, the PM _2.5 concentration gradually decreased, the achievement rate improved, and the EQS for PM _2.5 was finally achieved (100%) in fiscal year (FY) 2021. Because transboundary aerosol pollution is an important factor in Japanese air quality, here we analysed the long-term dataset of the satellite-measured fine-mode aerosol optical depth (AOD _f ) over the East Asian ocean to reveal the changes in the transboundary aerosol over East Asia. Overall, a decrease in AOD _f was seen over the entire East Asian ocean during the period analysed. A gradual declining trend in AOD _f was measured (−4% to −5%/year over the adjacent ocean around Japan) and corresponded well to the trend in PM _2.5 concentration observed in Japan (−5.3%/year) during FY2010–FY2021. Due to the domestic contribution in Japan, the negative trend was slightly greater for Japanese PM _2.5 concentration than for AOD _f over the adjacent ocean around Japan, and we concluded that the main reason for the dramatic air quality improvement in PM _2.5 in Japan was driven by the improvement of transboundary aerosol pollution over East Asia. In addition, the 12 year analysis period (FY2010 to FY2021) was divided into three parts: stagnation (FY2010 to FY2014), in which PM _2.5 and AOD _f remained the same as they were in FY2010; improvement (FY2015 to FY2018), in which PM _2.5 and AOD _f declined dramatically; and achievement (FY2019 to FY2021), in which PM _2.5 and AOD _f declined further.https://doi.org/10.1088/1748-9326/ad37ceEast Asiaenvironmental quality standard (EQS)aerosol optical depthMODIS |
| spellingShingle | Syuichi Itahashi Itsushi Uno Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021 Environmental Research Letters East Asia environmental quality standard (EQS) aerosol optical depth MODIS |
| title | Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021 |
| title_full | Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021 |
| title_fullStr | Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021 |
| title_full_unstemmed | Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021 |
| title_short | Dramatic improvement of aerosol pollution status over the East Asian ocean: from the establishment of Japanese environmental quality standard for PM2.5 in 2009 to its achievement in 2021 |
| title_sort | dramatic improvement of aerosol pollution status over the east asian ocean from the establishment of japanese environmental quality standard for pm2 5 in 2009 to its achievement in 2021 |
| topic | East Asia environmental quality standard (EQS) aerosol optical depth MODIS |
| url | https://doi.org/10.1088/1748-9326/ad37ce |
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