can private cars restriction policy help reduce air pollution in big cities? a case study of tehran

It is a common understanding that higher traffic volume leads to more pollutant air. therefore, when the air quality deteriorates, policymakers restrict private vehicles. this study aims to challenge this assumption by using statistical models including multivariate regression and ordered logistic regression models. these models are calibrated by employing datasets on air pollution, traffic quality, and weather conditions, for tehran the capital of iran. the results show that the coefficient of the traffic quality index (tqi), representing traffic volume, is not statistically significant. this finding suggests that traffic volume does not significantly impact air quality in tehran. among the variables, temperature has the most considerable effect on air pollution with a coefficient of -0.35 and has the highest significant coefficient with the p value of 0.083. the coefficients of all variables align with our previous knowledge. in fact, temperature and wind speed (coefficient is -0.14) show negative significant coefficients, implying that lower temperatures and slower wind speeds leads to higher levels of air pollution. conversely, tqi and humidity exhibit positive significant coefficients which their values are 0.03 and 0.05 in order, showing that increased traffic volume and higher humidity levels are associated with more polluted air. in conclusion, restricting private cars may not be a practical solution for addressing the issue of air pollution in tehran.