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Slow Decreasing Tendency of Fine Particles Compared to Coarse Particles Associated with Recent Hot Summers in Seoul, Korea

Category: MAPS-Seoul PM10 General Trend

Volume: 18 | Issue: 9 | Pages: 2185-2194
DOI: 10.4209/aaqr.2017.10.0403
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Greem Lee1, Hye-Ryun Oh1, Chang-Hoi Ho 1, Doo-Sun R. Park2, Jinwon Kim3, Lim-Seok Chang4, Jae-Bum Lee4, Jinsoo Choi5, Minyoung Sung5

  • 1 School of Earth and Environmental Sciences, Seoul National University, Seoul, Korea
  • 2 Department of Earth Sciences, Chosun University, Gwangju, Korea
  • 3 Climate Research Division, National Institute of Meteorological Sciences, Seogwipo-si, Korea
  • 4 Air Quality Forecasting Center, National Institute of Environmental Research, Incheon, Korea
  • 5 Air Quality Research Division, National Institute of Environmental Research, Incheon, Korea

Highlights

PM2.5 proportion and the number of days with a high PM2.5 proportion increased.
PM2.5 decreased more slowly than PM10-2.5 and air temperature increased in summer.
Discrepancy in the decreasing rates of PMs is due to secondary formations of PM2.5.
Changing air temperature can influence the proportion and the trend of PM2.5.


Abstract

In Seoul, South Korea, particulate matters (PMs) significantly decreased for the period 2005–2015 in concert with the implementation of air pollution reduction policies. This study reveals that PM with a diameter smaller than 2.5 μm (PM2.5) has a slower decreasing tendency than PM in the 2.5–10-μm range (PM2.5-10) during summer and that this discrepancy is attributable to the large increase in the summer surface air temperature for the analysis period (0.13°C year–1). During the daytime, especially in the afternoon when the hourly surface air temperature and its increasing rate are high, the difference between the decreasing rates of PM2.5 and PM2.5-10 is pronounced. The slower decrease in PM2.5 compared to PM2.5-10 likely results from the secondary PM2.5 formation being accelerated by the increase in the surface air temperature. Other atmospheric variables that can affect concentrations of PMs, such as insolation, relative humidity, precipitation, wind speed, and sea-level pressure, do not show a meaningful relationship with the discrepancy in the decreasing tendency between the two PMs. Our finding emphasizes the necessity of continuous monitoring and analysis of long-term variability in concentrations of PMs and related meteorological conditions, and the independent establishment of reduction policies for PM2.5 and PM2.5-10 to prepare for anthropogenic climate change and the subsequent air quality change.

Keywords

PM2.5 PM2.5-10 Surface air temperature Secondary formation Urban area

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