Old diesel cars will be banned from the area within Seoul’s four main gates starting December, the Seoul Metropolitan Government said Monday, as part of efforts to tackle air pollution.

Diesel cars classified as grade 5 in terms of emission levels -- some 2.18 million vehicles nationwide and 720,000 in Seoul and Gyeonggi Province -- will be excluded from the city center from 6 a.m. to 9 p.m. starting Dec. 1.

After that, a driver caught driving an old diesel vehicle in the city center without an emissions-reduction device can face a 250,000 won ($212.55) fine.

If all grade 5 cars are removed from the city center, the government expects the level of PM2.5 (fine dust) within the city center to be reduced 15.6 percent.

The crackdown will be carried out automatically at 45 locations in the city center using cameras.

The measure comes into effect after a five-month test run.

During that time, the country saw an 11.8 percent decrease in the number of diesel cars, from 2.47 million to 2.18 million. In Seoul and Gyeonggi Province, the number declined by 15.9 percent from 860,000 to 720,000, according to the city government.

The city government said it would push to expand the “green transportation zone” to include two large business and commercial districts -- Gangnam in southern Seoul and Yeouido -- by 2021.

The city will also consider expanding the range of diesel cars banned from the city to include grade 4 vehicles, with the aim of reducing car traffic 30 percent by 2030.

As part of the efforts to make the capital more eco-friendly, Seoul plans to offer more eco-friendly public transportation options.

“Car-sharing” services using electric vehicles will be available at more locations. The number of public bicycle stations will increase to 165 from the current 79, and the number of bikes will be doubled to 2,400 from 1,200.

Some 27 “green circle buses” -- serving four routes that connect the capital’s major spots, including Seoul Station and Namsan -- will start operations in January. The bus fare for green buses will be halved from 1,200 won to 600 won.

By Ock Hyun-ju (laeticia.ock@heraldcorp.com)