In October 2026, the NBCN monitoring station in Binningen recorded 13 days with a KBI of 1, indicating low air pollution, and 18 days with a KBI of 2, indicating moderate pollution. No days reached a KBI of 3 or higher, meaning there were no marked, significant, high, or very high pollution episodes during the month. The KBI, or Kurzzeit-Belastungs-Index, combines short-term exposure to ozone, nitrogen dioxide, and particulate matter into a single index that reflects the overall air quality burden on a given day. The mean concentrations for October 2026 were 36.9 µg/m³ for ozone, 12.1 µg/m³ for nitrogen dioxide, and 10.2 µg/m³ for PM10. The maximum daily concentrations were 106.6 µg/m³ for ozone, 45.0 µg/m³ for nitrogen dioxide, and 27.1 µg/m³ for PM10. All values are listed in Table 1, and regulatory thresholds are listed in Table 3.

Compared with the previous eight Octobers from 2018 to 2025, October 2026 was generally about average in terms of air pollution. The number of days with KBI equal to 1 ranked fifth out of nine years, while the number of days with KBI equal to 2 also ranked fifth, placing the month in the middle of the historical range. For maximum pollutant concentrations, October 2026 ranked third highest for ozone, sixth highest for nitrogen dioxide, and ninth highest for PM10, meaning the maximum PM10 value was the lowest recorded for any October in the comparison period. The mean ozone concentration ranked second highest, while the mean nitrogen dioxide concentration ranked ninth, the lowest among all compared years. The mean PM10 concentration ranked sixth. The monthly average and maximum values for October are reported in Table 2 and displayed in Figures 1 to 3.