Formaldehyde Continuous Monitoring at a Rural Station North of Rome: Appraisal of Local Sources Contribution and Meteorological Drivers

The formaldehyde (HCHO) dataset collected from January to December 2022 at the CNR Liberti Observatory (42.10° N; 12.64° E), a rural site located 30 km NE of Rome, is reported. The daily, weekly, and seasonal trends are examined. The highest average seasonal HCHO concentration (1.9 ppb) was measured during summer, whereas similar values (1.5 ppb) were found for winter and spring periods. The meteorological parameters monitored at the site allowed the interpretations of the maxima observed during the period investigated. The daily trends examined for the different seasonal periods, along with other pollutants available (NO2, NO, and O3), showed how the sources gradually shifted from primary to secondary. The occurrence of wildfires and other events in the area were also considered in explaining peak events (>4.2 ppb). The site examined was sometimes impacted by the nearby urban anthropic pressure of Rome, but in many cases, particularly during the summer months, the influence of the natural background surrounding the site was evident.