Applied Environmental Research

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The exhaust emissions of the air toxic benzene, toluene and xylene (BTX) from gasoline automobiles with and without catalytic converter have been measured in the idle mode condition. The exhaust gas samples from tailpipe were collected by tedlar bag in the vacuum box. The automobile samples were classified into four different groups as follows : (1) the new automobile (less than 5 years old) with catalytic converter, (2) moderate-age automobile (5-10 years old) with catalytic converter, (3) the moderateage automobile (5-10 years old) without catalytic converter and (4) the old automobile (more than 10 years old) without catalytic converter. The highest concentration of BTX was found in the old automobiles without catalytic converter group. The average concentrations of BTX in the old automobile without catalytic converter were 12.1 + 3.34 ppm, 33.9 + 7.1 ppm and 8.6 + 2.2 ppm, respectively. The lowest concentrations of BTX were found in the new automobiles with catalytic converter group. The results from statistical t-test showed that there was no significant difference of BTX concentration from automobile with and without catalytic converter at significant level (a) 0.05. It was also found that the age of engine has a strong influence on concentration of BTX in automobile emissions.

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