Characteristics of Urban Ground-Level Ozone in Korea

Abstract

This study considers the characteristics of ground-level ozone (O 3 ) in five Korean cities over a time period of 6-8 years. The focus of this study is daily maximum 1-hr and 8-hr concentrations. For all the study cities in the period examined, the mean and most of the percentiles (5, 10, 25, 50, 75, 90, and 95) for the daily maximum 1-hr and 8-hr concentrations showed increasing trends, although not all trends were statistically significant. The daily maximum 1-hr and 8-hr concentrations slowly increased during late winter, and peaks were attained during the summer season (from May to September). All the selected cities exhibited a high degree of correlation between their daily maximum 8-hr and 1-hr concentrations. The daily maximum 8-hr concentrations, which were climatologically equivalent to the Korean 1 hr/100 parts per billion (ppb) standard, were higher than the current 8 hr/60 ppb by a difference of 8-16 ppb. Compared with other cities in Korea, Seoul recorded a substantially higher frequency of days and hours with concentrations above 1 hr/100 ppb, and a higher frequency of days with concentrations above 8 hr/60 ppb and 8 hr/80 ppb. Seoul also recorded a substantially higher frequency of hours with concentrations above 1 hr/100 ppb than days with concentrations above 1 hr/100 ppb, implying that on some days severe exceedances persisted for more than one hour per day. During multiple-day episodes a North Pacific High dominated Korea, which is quite typical in Korea during the summer season.

Trends in Concentration of Ground-Level Ozone and Meteorological Conditions during High Ozone Episodes in the Kao-Ping Airshed, Taiwan

“…Thus, increases in surface O 3 are associated with the reductions in ambient concentrations of NO x and NMHC. These results are similar to those obtained in Toronto and Montreal in Canada, 15 Stevenage and central London in the United Kingdom, 16 Ulsar in Korea, 17 and three sites in Baton Rouge, LA (on July 24 and September 13, 1997), 18 which all exhibited an increase in O 3 with decreasing NO x or NMHC concentrations.…”

“…For example, the O 3 trends in Montreal, 15 Stevenage, and Sibton 16 were not statistically significant at the 95% confidence level, but sites in Toronto 15 showed small but statistically significant upward O 3 trends. O 3 trends in most cities in Korea 17 and mid-latitude areas 19 were not statistically significant at the 90 or 95% level. Three sites near Lake Michigan exhibited statistically insignificant declining trends, while another four sites near Lake Michigan showed statistically significant declining trends.…”

Forecasting Peak Daily Ozone Levels: Part 2—A Regression with Time Series Errors Model Having a Principal Component Trigger to Forecast 1999 and 2002 Ozone Levels

“…The value of 100 ppb also is recognized as the exceedance of 1-hr peak daily O 3 measurements internationally. 44 Development of the NO x Transfer Function Model. Forecast NO x , peak temperature, WD510, and WD1019 are needed to decide whether to turn on the PC trigger.…”

Exploring Ground Level Ozone Distributions with Micromap Plots in Seoul of Korea

“…The resulting increased photochemical precursors have forced environmental policy-makers to recognize the potential urban ozone (O 3 ) problem [1].…”