Air Benzene & Formaldehyde trends in north Italy: 2006 Winter Olympics vs 2025 Universiade games

Possible air pollution peaks during mega-events can raise population exposure to airborne toxic or carcinogenic pollutants such as Formaldehyde (FA) and Benzene (B). Torino, a city in the north-western part of Italy, hosted the 2006 winter Olympics and the 2025 Winter World University Games, providing a 19-year window to compare FA and B levels between two Olympic race sites: one urban site (Torino, 239 m. s.l.m.) and one mountain site (Pragelato, 1518 m. s.l.m.) about 90 km away from each other. A low-volume active sampler (1.0 l/min for 24 hours) were used for ten-day campaigns each month from November to April in 2006 and 2025. The mean FA concentration was 2.79 μg/m3 (Turin) and 3.02 μg/m3 (Pragelato) in 2025, compared with 1.46 μg/m3 and 1.31 μg/m3 in 2006. B was 2.42 μg/m3 (Turin) and 1.01 μg/m3 (Pragelato) in 2025, versus 4.10 μg/m3 and 2.30 μg/m3 in 2006. IARC classifies B as a human carcinogen (class 1) with no safe threshold and EU sets an annual ambient-air limit of 5 μg/m3. No outdoor regulatory limit currently exists for FA. A decrease in B and an increase in FA over time in both the two sites has been observed. Considering instead any differences between sites, B shows a higher concentration in Turin, both in 2006 and 2025. FA shows a significant difference between the two sites, also given the secondary origin of FA. To interpret the observed trends in association with Public Health impact, we are analysing concurrent meteorological data to better understand how mega-event-related air-pollution fluctuations may affect Public Health.

Key messages

• From 2006 to 2025, benzene decreased while formaldehyde increased at both Torino and Pragelato, indicating that mega-event air quality changed over time across both sites.

• Benzene remained higher in the urban site than in the mountain site in both years, whereas formaldehyde showed site differences consistent with its secondary origin and local atmospheric conditions.