South Korea began enforcing measures on Tuesday to reduce fine dust levels during the high-density winter season, restricting operations of grade-five emission vehicles in the Seoul metropolitan area until March 31.

It is the second time that the Environment Ministry's seasonal management system came into effect since it was introduced last year.

Grade-five emission vehicles without low-emission functionalities will be banned from 6:00 a.m. to 9:00 p.m. on non-holiday weekdays in Seoul, Gyeonggi Province and Incheon. Violators will face a fine of 100-thousand won.

The program, however, will be suspended when the nationwide College Scholastic Ability Test takes place on Thursday.

A total of 324 business establishments will participate in the emissions-cutting campaign, while state agencies and local governments plan to crack down on companies and industrial complexes that are suspected of illegal emissions.

Up to 16 coal plants will be halted until February while the output ceilings of others will be kept at 80 percent.