"Based on the provisions of the bill, cars will be categorized under four colors: blue, green, yellow and red, according to the vehicle emission standards,” he said, ISNA reported.
The LEZ (Low Emission Zone) system aims to reduce exhaust emissions of vehicles. Only vehicles that conform to higher emission standards are allowed to enter the zone.
"The idea came after studying the successful implementation of the system in countries such as England,” said Valiollah Azarvash, managing director of the Tehran Vehicle Technical Inspection Bureau.
There are currently two traffic restrictions for city vehicles: one is based on the odd-even license plate numbers (corresponding to odd-even days), and the other is the central restricted zone which is open only for public vehicles such as buses, taxis and ambulances.
The odd-even traffic zone came into force in 1998 and was implemented sporadically in the capital. It was later enforced in other bigger cities like Mashhad and Isfahan. As of 2005, it is enforced in Tehran.
Both restrictions were meant to help curb air pollution and preserve the environment. At present, the zone covers 15% of Tehran, but has so far failed to alleviate pollution problems.
"To further curtail air pollution in the metropolis, the bill with new proposals was proposed to the council,” Hamedani said.

Color Codes
The four color codes will decide entry of vehicles to odd-even zones which are to be renamed ‘low emission zone’.
Cars labeled ‘blue’, including sedans, SUVs and pickup trucks with an emission standard of Euro5 or above, and all electric or hybrid cars can enter the zone without restrictions.
The ‘green’ group including natural gas or gasoline fueled sedans, SUVs and pickup trucks with emission standards of Euro2 or above, fuel injected motorbikes with emission standards of Euro3 or above, and diesel vehicles with emission standards of Euro3 or above can use the zone according to the existing odd-even plan.
The ‘yellow’ label cars will include carburetor sedans, SUVs or pickup trucks and emission standards of below Euro2, carburetor motorbikes and diesel vehicles with emission standards of below Euro3. This group will be prohibited from entering the zone on high air pollution days.
Those in the ‘red’ group will comprise vehicles that lack valid technical inspection stickers as well as vehicles that have outlived their usefulness based on the standards set by law. They will not be allowed to operate within the city.
A workgroup will be formed to determine emission standards of vehicles to issue environment certificates, Hamedani said. "To make that happen, the technical inspection system must be linked with servers of the law enforcement force to facilitate and accelerate exchange of information.”