An Assessment of Automobile Emissions in Irbid, Northwest Jordan

Investigation of pollutants emitted by gasoline vehicles in metropolitan area of Irbid, Jordan has revealed four major factors affecting the emission rates of carbon monoxide (CO), carbon dioxide (CO2) and hydrocarbon (HC) and contributing to emission tests failure. These variables are vehicle age, fuel delivery system, fuel composition and availability of catalytic converter. Our observation also indicated that maintenance program has strong correlations with CO2 and HC but is poorly correlated with CO concentrations. Engine size and daily driving distance showed no statistically significant relationship with vehicular emissions. Structural equation modeling has been implemented to evaluate the cause-effect relationships among three constructs: vehicle variables, pollutants concentrations and emission test results. Results showed that fuel delivery system has significant effects on both CO and CO2 emissions and among the pollutants only CO2 has an influence on the emission test results. The highest total effect of fuel delivery system on CO2 concentrations and consequently on the test result is -0.0097.