Italy’s hot summer sends ozone levels sharply higher

Italy’s unusually hot summer brought a sharp deterioration in ozone levels, with many cities recording more days above the limit than during the same period in 2025. The findings come from data updated through the end of August by the Cambiamo Aria project.

The project is run by the Italian section of the International Society of Doctors for the Environment, together with Kyoto Club’s Sustainable Urban Mobility Observatory and the Clean Cities Campaign. It draws on data from regional environmental protection agencies and Italy’s national environmental protection system.

Ozone forms more readily under strong sunlight and high temperatures. The tolerable threshold of 120 micrograms per cubic meter, allowed on 25 days a year, was exceeded on 77 days at Bergamo-Meucci. Vicenza-Quartiere Italia recorded 69 days, Torino-Lingotto and Torino-Rubino 67 each, Milano-Verziere 66, and Verona-Giarol Grande 65.

The largest increases from 2025 included Torino-Lingotto, where exceedance days rose from 29 to 67, Brescia-Villaggio Sereno, from 12 to 58, Padova-Mandria, from 34 to 58, and Verona-Giarol Grande, from 29 to 65.

The report also pointed to high nitrogen dioxide levels, an air pollutant linked to combustion and motor traffic. Genova-Via Buozzi recorded 223 days above 25 micrograms per cubic meter and 88 above 50. Palermo recorded 215 and 95 days respectively, while Napoli-Ente Ferrovie recorded 196 and 56, and Catania 231 and 37. PM2.5 limits were also exceeded at several stations, including Torino-Rebaudengo with 129 days, Verona-Giarol Grande with 115, Napoli-Ente Ferrovie with 110, Milano-Marche with 101, and Padova-Mandria with 99.