The results of a study conducted by Tehran Air Quality Control Company on the fuel quality show that the gasoline supplied by gas stations during the summer (June 22- September 22) contained low octane and above standard levels of sulfur and benzene.
As part of the study, premium (unleaded) and Euro-IV gasoline samples were collected at random from five gas stations across the city and sent to the labs for evaluation, the company’s website reported.
It was found out that the quantity of sulfur in Euro-IV gasoline samples was on average 140 parts per million, way above the maximum sulfur content of 50 PPM set by the European Union. The average sulfur content in premium gasoline samples was estimated at around 100 PPM, twice the maximum limit.
The study also analyzed diesel fuel samples from five stations, which were found to contain low cetane numbers (indicator of the combustion speed of diesel fuel) and a standard quantity of sulfur.
Sulfur is a natural component in crude oil that is present in gasoline and diesel unless removed. Reducing the sulfur content in gasoline enables advanced emission controls and reduces air pollution.
The octane number of gasoline denotes its resistance to detonation. The higher the octane number, the more compression the fuel can withstand before igniting. Use of gasoline with lower octane numbers may lead to engine knocking.
Tehran Air Quality Control Company, affiliated to Tehran Municipality, is in charge of monitoring the air quality in the highly-polluted capital that is home to almost 13 million people and one of the most car-dependent cities in the world. The company also publishes seasonal reports of fuel parameters and their impact on air pollution.
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