Basel ozone peaked at 136 µg/m³, exceeding regulatory threshold.
July 9, 2026On July 8, 2026, Basel experienced a notable spike in ozone levels, with a maximum concentration of 136.2 µg/m³ exceeding the regulatory threshold, while nitrogen dioxide and PM10 remained low. This elevated ozone, ranking in the top 6% of recent daily maximums, is typical for a warm summer day with strong sunlight.
On July 8, 2026, the most notable air quality issue in Basel was elevated ozone. The maximum ozone concentration reached 136.2 µg/m³, which exceeded the regulatory threshold of 120.0 µg/m³. This value ranks 21st highest among the last 362 days, placing it in the top 6% of recent daily maximums. The average ozone concentration for the day was 99.6 µg/m³, which is above the 30-day average of 81.4 µg/m³ and the seasonal average of 78.6 µg/m³, indicating a significant spike.
Nitrogen dioxide and PM10 levels remained low. The maximum NO₂ concentration was 9.2 µg/m³, and the average was 5.7 µg/m³, both well below the regulatory limit of 80.0 µg/m³. PM10 had a maximum of 20.7 µg/m³ and an average of 15.3 µg/m³, also staying under the 50.0 µg/m³ threshold.
Compared to historical data since 2018, the day's ozone maximum of 136.2 µg/m³ is well below the all-time maximum of 206.3 µg/m³ recorded on June 27, 2019. The current NO₂ and PM10 levels are also far from their historical peaks. Overall, the air quality on this day was characterized by a notable but not extreme ozone exceedance, while other pollutants were low. The elevated ozone is typical for a warm summer day with strong sunlight, which promotes the photochemical formation of ground-level ozone.
Table 1: Statistics for Air Quality Parameters on 2026-07-08
| Constituent | Average µg/m³ | Maximum µg/m³ | Standard | Comments |
|---|---|---|---|---|
| NO2 | 5.9 | 21.7 | 80.0 | daily average may not exceed standard |
| Ozone | 81.9 | 136.2 | 120.0 | maximum hourly average may exceed standard only one time per year |
| PM10 | 9.6 | 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 | 75.9 | 181.9 | 89 |
| PM10 | 11.3 | 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.