SURFACE OZONE IN PISA (ITALY) - A 6-YEAR STUDY

The paper reports the results of ground level distribution of ozone in Pisa (Italy) in the periods May to September, 1986-1991. The recurrence of relevant levels of photochemically produced ozone is described. The maximum hourly peak (M1) proved to be 128 ppb and the average of the M1 peaks turned out to be 60 ppb. The threshold of 100 ppb was surpassed in 17 d. The average value of the 'daily highest consecutive 7-h mean concentrations' (M7) was 53 ppb. M1 and M7 are closely correlated and both show approximately a log-normal distribution. Monthly variations are relatively low, with September showing the lowest values. The years 1986 and 1991 show values that are clearly higher than the other years, and no temporal trend has been verified. Ozone levels were positively correlated with temperature and solar radiation. The paper reports the results of ground level distribution of ozone in Pisa (Italy) in the periods May to September, 1986-1991. The recurrence of relevant levels of photochemically produced ozone is described. The maximum hourly peak (M1) proved to be 128 ppb and the average of the M1 peaks turned out to be 60 ppb. The threshold of 100 ppb was surpassed in 17 d. The average value of the `daily highest consecutive 7-h mean concentrations' (M7) was 53 ppb. M1 and M7 are closely correlated and both show approximately a log-normal distribution. Monthly variations are relatively low, with September showing the lowest values. The years 1986 and 1991 show values that are clearly higher than the other years, and no temporal trend has been verified. Ozone levels were positively correlated with temperature and solar radiation