Yousef Rashidi, the head of the Air and Climate Division of Iran's Department of Environmental Protection, reported that in an unprecedented trend, Tehran’s air quality has not reached unhealthy levels in the past two months.

In an interview with IRNA, Rashidi said one of the chief causes of the rise in air quality in the capital is the distribution of higher-quality gasoline.

Iranian authorities had announced earlier that production of gasoline by petrochemical plants, which was said to be a major cause of increased air pollution in the country, has been halted.

The administration of Mahmoud Ahmadinejad turned to gasoline production through petrochemical plants after the U.S. imposed unilateral sanctions on Iran, preventing it from supplying its gasoline needs through international purchases.

Following the election of Hassan Rohani last spring, the new minister of oil and head of the Department of the Environment have stopped the production of petrochemical gasoline for use in automobiles.