A thick haze from China blanketed Baenknyeong Island just off the western coast of Korea and blew into Seoul on Sunday carried by westerly winds.

This month coal use has surged to heat homes in the world's most populous country, causing the concentration of ultrafine particles to surge to 461㎍/㎥ near Mt. Tai in Shandong Province just across the West Sea.

That is more than nine times the acceptable limit in Korea of 50㎍/㎥.