Monitoring and biomonitoring of surface ozone in Florence, Italy.

An ambient air study was conducted in the city of Florence, Italy, in the summer 1996. Tropospheric ozone was continuously monitored with automatic analyzers in three stations, two located in the urban area and one in the hilly surroundings (Settignano). A biomonitoring campaign based on the tobacco cv. Bel-W3 plants was performed in the same area. The highest values were constantly recorded in the Settignano station. The highest 1-hour mean recorded was 197 nl/l; the accumulated exposure over a threshold of 40 nl/l (AOT40) was well above the critical levels standards for protection of the vegetation. A consistent temporal variation was observed and July proved to be the month with the highest ozone levels. Cumulative frequency distribution of ozone maximum daily concentrations exhibited a good fitting to log-normality. No 'week-end' effect was observed. Biomonitoring data were in good agreement with chemico-physical ones.