Preliminary evaluation, using passive tubes, of carbon monoxide concentrations in outdoor and indoor air at street level shops in Genoa (Italy)

Preliminary information on carbon monoxide (CO) concentrations (exposure time: 8 h) both inside and outside 38 randomly selected shops situated on four heavy traffic streets of Genoa was obtained using passive diffusion tubes. Reproducibility and accuracy of this analytical method were tested in real outdoor urban conditions and found within 25%; the detection limit was 1 mgm−3 of CO. The highest mean CO concentrations (15.8 ± 2.2 mgm−3) were found inside shops on Balbi street, a narrow “canyon street”. Only in two small shops and two bars (both with many smokers) and in a delicatessen, were indoor CO concentrations significantly higher than outdoor values. The mean outdoor CO concentrations (mgm−3) along the four streets considered (XX Settembre, Balbi, Rolando, Fillak) were 7.4 ± 2.2; 14.5 ± 8.7; 5.8 ± 0.4; 10.5 ± 3.7, respectively. No statistical difference was found, comparing the mean indoor CO concentration with the mean CO outdoor value, measured simultaneously along the sidewalks of each street. CO concentrations in 10 shops without smokers and the nearest outdoor measurements were linearly correlated (r = 0.99; p < 0.0001). No statistically significant difference was found comparing indoor CO pollution in shops with smokers (CO: 8.0 ± 5.4) to those without smokers (CO: 7.1 ± 4.6). Forced ventilation, with air intake far from traffic, proved effective in some specific situations in reducing indoor CO concentrations.