The results of ozone tests obtained are shown in Figure 4. The graph shows the values of the baseline (BF 1), followed by a first measure with the filtering system (WF),
a second measure of baseline (BF2), a subsequent measurement without filtering system (WOF), finally a third measure of baseline (BF3) was carried out.
In fact, under normal conditions the half life time of ozone is about 10 min and it is determined mainly by changes of air and temperature. As shown in Figure 4, the values of Baseline 1, determined initially, are quite stable and the range is between 15 and 20 ppb. The following monitoring was carried out during printing, with filtering system. Compared to baseline it is evident an increase of ozone’s concentration. After a few minutes, a measure of ozone shows a return of the values to initial concentrations (Baseline 2). It was done a measure during a second printing, without filtering system. The results are clearly in evidence: the values of ozone increased significantly, reaching values
around 45 - 50 ppb. Finally it was made last measure of the concentration of ozone in the absence of printing (Baseline 3) further confirms the re-establishment of the values monitored initially.