Basel ozone hit 154.9 µg/m³, exceeding Swiss limit on July 10.
July 11, 2026On July 10, 2026, Basel experienced elevated ozone levels, with a maximum concentration of 154.9 µg/m³ that exceeded the Swiss regulatory threshold of 120 µg/m³. Other pollutants like nitrogen dioxide and PM10 remained well below their respective limits.
On July 10, 2026, the most notable air quality issue in Basel was elevated ozone. The maximum ozone concentration of 154.9 µg/m³ ranked 7th highest among the last 365 days. This value exceeded the regulatory threshold of 120 µg/m³, which is the maximum hourly average allowed under the Swiss Clean Air Ordinance. The average ozone concentration for the day was 107.7 µg/m³.
Nitrogen dioxide levels were low, with a maximum of 26.4 µg/m³ and an average of 10.6 µg/m³. These values did not exceed the regulatory threshold of 80 µg/m³ for the daily average. Fine particulate matter (PM10) was also moderate, with a maximum of 25.1 µg/m³ and an average of 16.1 µg/m³, both well below the daily average limit of 50 µg/m³.
Comparing the current measurements to historical data since 2018, the maximum ozone concentration of 154.9 µg/m³ is notably high but remains below the all-time maximum of 206.3 µg/m³ recorded on June 27, 2019. The average ozone concentration of 107.7 µg/m³ is above the seasonal average of 79.9 µg/m³, indicating a significant elevation. The maximum nitrogen dioxide concentration of 26.4 µg/m³ is well below the historical maximum of 83.2 µg/m³ from February 15, 2019, and is within typical ranges. The maximum PM10 concentration of 25.1 µg/m³ is also far below the all-time maximum of 165.1 µg/m³ from August 24, 2023, and is consistent with normal levels.
Overall, the air quality on July 10, 2026, was unusual due to the elevated ozone levels. The day was characterized by a considerable air quality index rating and an ozone exceedance. The high ozone concentration is likely driven by strong solar radiation and high temperatures typical of summer, which promote the photochemical formation of ground-level ozone. This pattern is consistent with typical summer smog events in the region.
Table 1: Statistics for Air Quality Parameters on 2026-07-10
| Constituent | Average µg/m³ | Maximum µg/m³ | Standard | Comments |
|---|---|---|---|---|
| NO2 | 6.7 | 26.4 | 80.0 | daily average may not exceed standard |
| Ozone | 85.9 | 154.9 | 120.0 | maximum hourly average may exceed standard only one time per year |
| PM10 | 11.0 | 27.0 | 50.0 | daily average may not exceed standard |
Table 2: Statistics for Air Quality Parameters for the Month of July, since 2018
| Constituent | Average µg/m³ | Max µg/m³ | Exceedances |
|---|---|---|---|
| NO2 | 7.7 | 56.2 | 0 |
| Ozone | 76.1 | 181.9 | 91 |
| PM10 | 11.4 | 43.3 | 0 |
Figure 1: NO2 Concentrations in Basel, last 90 Days
Figure 2: Ozone Concentrations in Basel in the last 90 Days
Figure 3: PM10 Concentrations of last 90 Days at Binningen/Basel
Additional resources: Umweltbericht beider Basel, Luftqualität Nordwestschweiz, Luftreinhalte-Verordnung (LRV)
🤖 This text was generated with the assistance of AI. All quantitative statements are derived directly from the dataset listed under Data Source.