Vehicle fuel (gasoline and diesel) sold by four Korean oil refinery companies in the metropolitan area during the second half of 2015 were rated on the top level with five stars (★) in the environmental quality rating.
 

* Four Korean oil refiners:  SK Energy, GS Caltex, Hyundai Oilbank, and S-Oil
 

In line with the Government 3.0 policy which pursues active sharing of and respect for public data, Metropolitan Air Quality Management Office (Administrator Song Hyunggeun) announced the result of evaluation on environmental quality rating of vehicle fuel sold around the capital area in the latter half of 2015.
 

A result of the comprehensive evaluation showed that SK Energy, GS Caltex, Hyundai Oilbank and S-Oil received the top ranking with five stars, while Nonghyup and Korea National Oil Corporation (KNOC) were given four stars.
 

In terms of diesel, the four major domestic oil refiners, Nonghyup, KNOC and Hanwha Total all received five stars.
 

* The evaluation of Hanwha Total was completed as of July 2015 as the company stopped the operation of its Pyeongtaek Oil Storage (diesel) at the point.

Looking at specific criteria of evaluation, all of the four major oil refiners received the five-star grade in four items out of six criteria for their gasoline including aromatic compounds.
 

* Four criteria: benzene content, aromatic compounds, sulfur content, 90% distillation temperature

With respect to vapor pressure that affects emissions of volatile organic compounds (VOCs), GS Caltex ranked the highest with three stars while SK Energy, Hyundai
Oilbank and S-Oil all received two stars. All the four refiners were rated with two stars with regard to olefin content which increases ozone-forming substances.

Nonghyup that supplies gasoline to thrifty gas stations received five stars in four criteria and two stars in olefin content and vapor pressure. KNOC got five stars in benzene content and sulfur content, four stars in aromatic compounds, three stars in olefin content and two stars in 90% distillation temperature and vapor pressure.

For diesel fuel, all four domestic oil refiners, Nonghyup, KNOC and Hanwha Total were rated with five stars in four criteria including sulfur content.

* Four criteria: sulfur content, density@15℃, polycyclic aromatic hydrocarbons, and cetane index

Only SK Energy got four stars in lubricity while other companies received five stars. For aromatic compounds, all companies except S-Oil which received three stars were given four stars.

In respect of diesel fuel, all companies subject to the evaluation received five stars in the comprehensive evaluation for 19 consecutive times from the latter half of 2006 to the latter half of 2015.

Under the Special Act on the Improvement of Air and Environment for Seoul Metropolitan Area, the evaluation on vehicle fuel environmental quality has been carried out since 2006 with an aim to induce consumers to purchase eco-friendly fuel and encourage vehicle fuel manufacturers and suppliers to voluntarily improve environmental quality of their products.

The evaluation is conducted twice a year for six months by collecting 45 samples of gasoline and diesel fuel from oil storages and gas stations in the metropolitan area to grade the environmental quality.

By analyzing the respective six items including aromatic compounds for gasoline and diesel, the evaluation is graded in five classes from five stars to one star, which helps enhance the environmental quality vehicle fuel.

* Criteria for gasoline: aromatic compounds, sulfur content, benzene content, olefin content, vapor pressure, and 90% distillation temperature

* Criteria for diesel: aromatic compounds, sulfur content, density@15℃, polycyclic aromatic hydrocarbons, lubricity, and cetane index