Tehran has experienced 117 days of healthy air in the past 5 months, while in the same period last year it was only 47 days.
Tehran air pollution in the first 5 months of the year (started March 21) has decreased by about 25% compared to the same period last year, said Saeed Motesadi, official at the Department of Environment (DoE).
Phasing out sub-standard methods of production and distribution of petroleum fuel is one of the reasons for reduction of air pollution in larger cities, especially the Capital. The latest DoE analysis of petrol distributed in Tehran indicates that percentage of benzene was below 1%.
The gasoline in Karaj also contains 1% benzene while gasoline in Tabriz has a higher rate.
Euro-4 standard petrol has been distributed in Tehran, Karaj, Tabriz, and Arak so far.
Under the agreement with the petroleum ministry, distribution of Euro-4 petrol will apply to Isfahan Province from October.
