Long-Term Changes of Positive Anomalies of Erythema-Effective UV Irradiance Associated with Low Ozone Events in Germany 1983-2019

In order to assess whether there is an increasing need for adaptation to the associated human health risks, the long-term occurrence (1983-2019) of low-ozone events (LOEs) with associated near-surface anomalies of erythema-effective UV irradiance was examined using an impact-related approach. Based on satellite data, means of four locations in Germany (Sylt, Berlin, Frankfurt, Munich) were compared for three subperiods (T1: 1983-1989, T2: 1990-1997, T3: 1998-2019). The period of peak global ozone depletion in the 1990s (T2) is characterized by a larger frequency of LOEs than the preceding (T1) and the subsequent (T3) subperiods. During the most recent subperiod (T3), the mean number of LOEs is 1.1 +/- 0.5 events/year, with a variability of 0 to 4.2 +/- 0.8 events/year, and shows a statistically significant decrease in the annual number of -4.8%/year. The annual totals of the LOE-associated anomalies of the erythema-effective UV radiation dose show no trend during T3. With regard to LOE-associated UV index anomalies, spring is the season most affected by LOEs, with more than half of all cumulative UV peak loads, while the absolute maximum values of the LOE-associated UV index anomaly of about 1.8 UV index occur near the summer solstice. Within the most recent subperiod (T3), summer contributes an increasing share of the peak loads. Overall, the study confirms that LOEs pose health risks due to intermittent, pronounced positive anomalies in erythema-effective UV irradiance and therefore require special attention and adaptation measures. Long-term changes can be identified, but to date there has been no evidence of an increasing health risk in Germany.

Automated summary

This study examined the long-term occurrence of low-ozone events (LOEs) in Germany from 1983 to 2019 and found that the 1990s had the highest frequency of LOEs. However, there has been a significant decrease in the number of LOEs in the recent period (1998-2019). Although LOEs pose health risks, there is currently no evidence of an increasing health risk in Germany.