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Longer-Lasting Episodes in the 2015 Ozone Season in Italy in Comparison with Recent Years
* 1, 2 , 3 , 3 , 1, 2
1  University of L’Aquila, L’Aquila, Italy
2  Centre of Excellence CETEMPS, University of L’Aquila, L’Aquila, Italy
3  Istituto Zooprfilattico dell’Abruzzo e del Molise ‘G. Caporale’, Teramo, Italy


The year 2015 is considered the hottest on records at the global scale, since reliable temperature measurements are available. Ambient air quality is strongly influenced by meteorological conditions, and daytime surface ozone concentrations are generally positively correlated with temperatures. We thus analysed 2015 ozone data over Italy to check if exceptional ozone values reflected the exceptional temperatures. To this end, we evaluated the ozone season in 2015 compared to the 2002–2015 trend, using data from 24 selected monitoring stations and analyzing the exceedances of limit values imposed by the European directive. We found that 2015 was one of the hottest years over Italy, and the ozone season was one of the most severe in the last ten years. In 2015, the average duration of ozone episodes (the number of consecutive days with daily maximum 8-hour-average values higher than the threshold of 120 µg·m−3) was about 4 days, similar to that of 2006 and less than that of 2003 which was about 5 days. This duration is longer than the average observed in recent years, which is less than 3 days. Furthermore, the mean maximum concentration of ozone events was the second on record together with 2006, after the notable heatwave of 2003.

Keywords: ozone; air quality; temperature; heat wave; Italy; ozone trend