Thirty healthy volunteer males were included in this study. These students were living in the same area, Phayathai District but in the place about 0.5 kilometers away from roads. All subjects in this study presented the same eating and drinking habit. All subjects were healthy adults. Before the study, all were interviewed for possible exposure to other sources of non - traffic vapors, especially for smoking and volatile substance. The exclusion was set in case with history of possible exposure to those vapors.
Each subject provided a urine sample for laboratory analysis. Concerning the laboratory analysis for urine phenol, the standard colorimetric method was used [ 5].
The statistical analysis of the results was carried by SPSS 7.0 Mean and standard deviation of urine phenol level among these subjects were calculated.