This report is published because the daily maximum ozone concentration on 2024-08-30 exceeded the 95th percentile of all values measured in August. On this day, the air quality in Basel showed elevated levels of certain pollutants. The maximum concentration of ozone (O₃) reached 170.7 µg/m³, with an average of 96.2 µg/m³. Nitrogen dioxide (NO₂) had a maximum of 29.9 µg/m³ and an average of 13.6 µg/m³. Particulate matter (PM₂.₅) recorded a maximum of 18.0 µg/m³ and an average of 15.2 µg/m³. The particle count (CPC) peaked at 18,410 particles/cm³, averaging 10,043 particles/cm³. Elemental carbon (EC) reached a maximum of 0.7 µg/m³, with an average of 0.5 µg/m³. Sulfur dioxide (SO₂) had a maximum of 4.0 µg/m³ and an average of 1.0 µg/m³. The NOx levels, expressed as NO₂ equivalent, peaked at 38.9 µg/m³, averaging 15.1 µg/m³.

Comparing these values to historical averages and maxima since 2018, the ozone levels on this day were unusually high, significantly exceeding the average of 67.99 µg/m³ for the season and the last 30 days' average of 72.4 µg/m³. The maximum recorded ozone value of 170.7 µg/m³ matched the seasonal high, indicating an exceptional event. NO₂ levels were within the normal range, with the maximum value close to the seasonal high of 30.6 µg/m³. PM₂.₅ concentrations were higher than the seasonal average of 6.57 µg/m³, indicating elevated particulate matter levels. The particle count was below the historical maximum but above the average, suggesting moderate pollution. EC levels were within normal ranges, while SO₂ levels were slightly above average but not alarming. NOx levels were elevated compared to the seasonal average of 8.11 µg/m³, indicating increased nitrogen oxides.

Overall, the air quality on 2024-08-30 was characterized by unusually high ozone levels, which were significantly above historical norms. This could be due to specific weather conditions or local emissions. The elevated PM₂.₅ and NOx levels also suggest increased pollution, which may warrant further investigation to determine the underlying causes and potential health impacts.