Science & Tech · Science & Environment · 2 hrs ago
Ulsan issued ozone alerts on 14 days this year, up from 12
Ulsan, a city in South Korea, issued ozone alerts on 14 days this year, with 26 alerts in total.
That was two more alert days and one more alert than in 2025.
The first alert came on April 26, compared with June 8 last year.
The alert system runs from April to October and notifies people when ozone levels are high.
Researchers said rising temperatures, less rain and more sunshine may have contributed to higher ozone levels.
High ozone can irritate the eyes, nose and breathing system, so people are advised to limit outdoor activity during alerts.
The city sends alerts through its website, electronic signs and text messages, and residents can sign up for notifications on the local research institute’s website.
Ulsan issued ozone alerts on 14 days this year, two more days than last year.
The alerts were issued 26 times, compared with 25 times in 2025.
The first alert this year was issued on April 26, earlier than the first alert on June 8 last year.
Researchers said higher temperatures, less rainfall and sunshine duration increase may have raised ozone levels.
Alerts were most frequent in the central-northern area and between noon and 2 p.m.
- Who
- Ulsan Institute of Health and Environment reported the alerts.
- What
- Ulsan issued ozone alerts on 14 days, in 26 instances.
- When
- During the ozone alert season from April 1 to October 31, 2026; the first alert was on April 26.
- Where
- Ulsan, South Korea.
- Why
- Higher temperatures, less rainfall and fewer rainy days, and increased sunshine duration are thought to have raised ozone levels.
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Ulsan’s first ozone alert was issued on June 8; alerts were issued on 12 days in total.
Ulsan’s ozone alert system operated during its annual season.
Ulsan issued its first ozone alert of the year.
The Ulsan Institute of Health and Environment reported 26 alerts across 14 days.
- Alerts in 2026
- 14 days; 26 instances
- Alerts in 2025
- 12 days; 25 instances
- First alert in 2026
- April 26
- Most alerts by area
- Central-northern area, 13 instances
- Alert season
- April 1 to October 31