NOTE ON THE COMPARISON OF AIR POLLUTION IN SEOUL BEFORE CORONAVIRUS (BC; BEFORE COVID-19) AND AFTER CORONAVIRUS (AC; AFTER COVID-19) VIA STATISTICAL REASONING

The world is currently, facing a distinct new era between pre-coronavirus and post-coronavirus. Seoul is the capital of the Republic of Korea and is one of the most polluted cities in the Organization for Economic Cooperation and Development (OECD) member countries in terms of particulate matter (PM). According to recent research (Chang 2020), the data before corona (BC) does not provide enough evidence that the average density of PM10 and PM2.5 in Seoul during spring and winter 2018 or 2019 was reduced compared with 2012 or 2013.In this article, we compare the average concentration of fine dust during the first half of 2018 (BC) and that during the first half of 2020 (AC) via statistical reasoning. According to our analysis, there is significant evidence that the average density of the PM in Seoul AC is currently reduced, compared with that of BC. Our method has the advantage of providing statistically valid and reliable results compared to the simple average comparison which is available in National Institute of Environmental Research report in Republic of Korea. We also present brief comments on the implications of our results. Our analysis and results could be used to define the current situation related to fine dust in Seoul, and to establish related policies and evaluate their performance.