▲ An electronic display board on Sejong-daero in front of Seoul City Hall displays information regarding an ozone advisory issued across Seoul in July 2025.
The Ministry of Climate, Energy and Environment announced that it has prepared an amendment to the Clean Air Conservation Act, which includes clarifying the criteria for lifting ozone advisories, and that it will take effect starting tomorrow, July 15.
Currently, ozone advisories are regulated to be issued when the ozone concentration at automated air monitoring stations reaches 0.12 ppm or higher, and to be lifted when it falls below that same level.
Because the threshold for both issuing and lifting the advisory is the same at 0.12 ppm, there has been confusion caused by the advisory repeatedly being issued and lifted when ozone concentrations fluctuate slightly around that level.
In response, the amendment stipulates that an ozone advisory will be issued when the ozone concentration is 0.12 ppm or higher, and will be lifted when it drops below 0.10 ppm.
(Photo: Yonhap News)
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