The Euro 4 emission standard became mandatory for all new cars after the Iranian president unveiled the first cars produced with the Euro Four standard. 

According to the officials, the effects of this and other pollution-fighting measures will be remarkable, because Iran has imposed the strict Euro Four standard two years ahead of schedule, the same time it is imposed in developed countries. But Iran will soon go a notch higher.

European emission standards define the acceptable limits for exhaust emissions of new cars. These are defined in a series of European Union directives staging the progressive introduction of stringent standards.

Air pollution has become a major headache for Iranian officials, especially in major cities such as the capital, where air quality continues a downward slide. The World Bank estimates losses inflicted on Iran's economy as a result of deaths caused by air pollution at more than half a billion dollars a year.