The density of fine dust fell to normal levels in Seoul on Thursday, as winds blowing from the north scattered away extraordinarily heavy concentrations of dust particles.

The Seoul Metropolitan Government said it lifted a fine dust warning in the capital city at 6 a.m., citing a gradual reduction in the levels of ultrafine particles.

The daily average of PM 2.5 surged close to 150 micrograms per cubic meter in Seoul on Tuesday and Wednesday, the highest levels since record-keeping began in 2015.

South Korea's authorities classify levels of PM 2.5 above 35 micrograms per cubic meter as "bad" and above 75 micrograms as "very bad," while the WHO recommends keeping levels below 25 micrograms.

Elsewhere in the nation, the fine dust density was still bad Thursday morning, reaching 102 micrograms in Busan, 92 in Sejong, 70 in North Jeolla Province and 54 in Gyeonggi Province as of 10 a.m.

But most provincial areas are expected to regain normal levels of fine dust in the afternoon, due to winds from the north, the NIER said.

"Strong wind blowing from the north will scatter away fine dust particles in most of South Korea in the afternoon," said a forecaster at the institute.

He said the fine dust levels will remain normal in most of the nation Friday but warned that heavy dust concentrations could return this weekend. (Yonhap)