Temporal variability of surface air pollutants in megacities of South Korea

Abstract

This study investigated the various temporal (weekly, monthly, and inter-annual) variability of air pollutants (PM10, SO2, NO2, O3, CO) in seven megacities in South Korea (Seoul, Busan, Incheon, Daegu, Gwangju, Daejeon, and Ulsan). We found that the general decreasing trend of PM10, SO2, NO2, and CO. An exceptional pollutant is O3, showing a clear increasing trend consistently in all seven megacities. Seasonally PM10, SO2, NO2, and CO have the highest level in winter due to the large fossil-fuel combustion for the heating demand, but O3 shows the maximum peak in summer related to the intensified photochemistry. Based on the analysis for percentile values of air pollutants, we recognized that some patterns of air pollutants in Korean megacities are overlooked: O3 increase is not perfectly related to the NO2 pattern, somewhat high SO2 in the coastal cities, ambiguous weekly pattern on Monday (as a weekday) and Sunday (as a weekend). Through this comprehensive analysis of multiple air pollutants using the percentile values, the characteristic for various temporal change of air pollutants in Korean megacities can be better understood, and some useful ideas for the air quality control in the urban region can be also excavated.

Statistical Characteristics of Air Quality Index DAQx*-Specific Air Pollutants Differentiated by Types of Air Quality Monitoring Stations: A Case Study of Seoul, Republic of Korea

“…This study is not purely statistical in nature because it also takes into account the DAQx* concentration ranges of air pollutants. Thus, it supplements previous statistical studies on characteristics of air pollutants in Seoul [6,14,[37][38][39], which are primarily related to annual trends, daily cycles of hourly means, weekly cycles of daily means, and annual cycles of monthly means but not to daily maximum 1 h means. Moreover, they do not sufficiently account for the differences between and within AQMS types.…”

“…Seoul is the capital of the Republic of Korea, has a population of approximately 11 million (as of November 2022), an area of approximately 605 km 2 [29,40], and a relatively high level of air pollution [6,14,37,43], which was also confirmed by the DAQx* results in [36]. This is one of the main reasons for the relatively high density of AQMSs operated by the Korea Environment Cooperation in Seoul [44].…”

“…Assessments of air pollution using AQIs for different AQMS types, which is interesting especially in larger cities, require air pollutant data from comparatively many AQMSs. In this regard, megacities, which often suffer the most from high air pollution and therefore have fundamental adverse impacts on human health, are of particular importance [2,[12][13][14].…”

“…Therefore, the objective of this case study is to identify and quantify the variability in the four DAQx* air pollutants within and between AQMS types. Since they are already the subjects of previous investigations, this study does not address the determination of statistical air pollutant concentrations at individual AQMSs [14,32,38,39] or the model-based creation of maps showing spatial distributions of air pollutant characteristics in Seoul [32,[40][41][42].…”

Development of Surface Observation-Based Two-Step Emissions Adjustment and its Application on Co, Nox, and So2 Emissions in China and South Korea

“…The ambient concentrations of PM 2.5 , SO 2 , and NO x in Northeast Asia have declined recently (Ali et al, 2023;Bae et al, 2023;Lee et al, 2022;Zhai et al, 2021). Previous studies reported that this downward trend resulted from emission reductions by strict emission control policies and social issues such as the COVID-19 pandemic (Bae et al, 2021;Hasnain et al, 2023;Yao et al, 2023;Zhang et al, 2023).…”