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Geoscience Communication An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/gc-2019-16
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/gc-2019-16
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 06 Sep 2019

Submitted as: research article | 06 Sep 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Geoscience Communication (GC).

Novel index to comprehensively evaluate air cleanness: the Clean aIr Index

Tomohiro O. Sato1, Takeshi Kuroda2,1, and Yasuko Kasai1,3 Tomohiro O. Sato et al.
  • 1National Institute of Information and Communications Technology
  • 2Tohoku University
  • 3University of Tsukuba

Abstract. Air quality on our planet has been changing in particular since the industrial revolution (1750s) because of anthropogenic emissions. It is becoming increasingly important to visualize air cleanness, since clean air deserves a valuable resource as clean water. We defined a novel concept, namely Clean aIr Index, CII, to quantify the level of air cleanness in terms of a global standard. The CII is a simple index defined by the normalization of the amount of individual air pollutants. A CII value of 1 indicates completely clean air (no air pollutants), and 0 indicates the presence of air pollutants up to numerical environmental criteria for the normalization. In this time, the air pollutants used in the CII were taken from the Air Quality Guidelines (AQG) set by the World Health Organization (WHO), namely O3, particulate matters, NO2 and SO2. We chose Japan as a study area to evaluate CII because of the following reasons: i) accurate validation data, as the in situ observation sites of the Atmospheric Environmental Regional Observation System (AEROS) provide highly accurate values of air pollutant amounts, ii) obvious numerical criteria, namely the Japanese Environmental Quality Standards given by the Ministry of the Environment (MOE). We quantified air cleanness in terms of the CII for the all 1896 municipalities in Japan, and used Seoul and Beijing to evaluate Japanese air cleanness. The amount of each air pollutant was calculated using a model that combined the Weather Research and Forecasting (WRF) and Community Multiscale Air Quality (CMAQ) models for 1 April 2014 to 31 March 2017. The CII values were validated by comparing the WRF-CMAQ model and AEROS measurements for selected six cities, and an average correlation coefficient of >0.61 was obtained. The CII value of Tokyo averaged for the study period was 0.75, which was 1.2 and 1.9 times higher than that of Seoul (0.64) and Beijing (0.39), respectively. The extremely clean air, CII > 0.93, occurred around west of the Pacific coast, i.e., Kochi, Mie and Wakayama Prefectures, and southern remote islands of Tokyo during summer with transport of clean air from the ocean. The average CII value for the all Japanese municipalities was 0.78 over the study period. We presented Top 100 clean air cities in Japan using the CII. We confirmed that the CII enabled the quantitative evaluation of air cleanness. The CII can be useful value, for example, for encouraging sightseeing and migration, as tasty air, insurance company business, and city planning. The CII is a simple and fair index that can be applied to all nations.

Tomohiro O. Sato et al.
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Tomohiro O. Sato et al.
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Short summary
Air deserves a valuable resource as water. We defined novel index, Clean aIr Index (CII), to evaluate air cleanness, in terms of a global standard. Japan was chosen as a study area. Air cleanness of Tokyo was 1.2 and 1.9 times higher than that of Seoul and Beijing, respectively. Extremely clean air occurred around west of the Pacific coast and southern remote islands of Tokyo during summer. CII can be useful value, for example, for encouraging sightseeing and migration, as tasty air.
Air deserves a valuable resource as water. We defined novel index, Clean aIr Index (CII), to...
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