This study presents the results of man's exposure to formaldehyde, carried out in indoor and outdoor environments in the city of Ferrara. The processes were obtained on average concentration measurements carried out for one month by indoor, outdoor and personal samplings. Concentration values obtained by personal samplings (PE) were compared to both outdoor and indoor values, the latter including domestic and working environments. The results showed that there was a significant difference between formaldeyde concentrations outdoor and PE (p = 0,03 < alpha = 0,05), while a significant difference was not found between indoor and PE. Indoor values (values as average of 38 samples) were 19,5 microg/m3, outdoor ones were 6,9 microg/m3 and PE 19,9 microg/m3. The average indoor value in domestic environments (20,7 microg/m3) was higher than the value found in working environments (17,9 microg/m3). Binary comparisons showed that indoor and outdoor, together with indoor and personal samplings, display the same variability of formaldehyde concentrations.