A layer of fine dust has blanketed the peninsula for days, raising public health concerns, officials said Thursday.

According to the Korea Meteorological Administration, many provinces have recorded a high level of fine dust over the past week, prompting the cities to issue alerts.

North Jeolla Province issued a fine dust advisory on Thursday morning as the average concentration stayed above 120 micrograms per cubic meter for 24 hours, with Iksan recording the highest of 187 micrograms per cubic meter.

Jejudo Island and North Chungcheong Province had also issued fine dust advisory warnings as of 8 a.m.

On Wednesday, Seoul City issued an ultrafine advisory for a half day as the PM-2.5 concentration exceeded 100 micrograms per cubic meter. This was the first issuance in this fall.

The measure was lifted early Thursday, but the city continued monitoring the level, as the ultrafine dust level is still “bad” with over 50 micrograms per cubic meter.

The stagnant atmospheric flow and recent drought have worsened the fine dust level, an environmental agency said.

“There is little wind flow now as the east wind has blocked the westerlies, leaving the fine dust stagnant in the west coast. The lack of rainfall also aggravated the dust accumulation,” the National Institute of Environmental Research said.

The institute added that 40 to 50 percent of the fine dust originates from the local air pollution while 30 to 40 percent comes from China.

The weather agency forecast that the fine dust would continue until early next week, when rain is expected.

By Lee Hyun-jeong (rene@heraldcorp.com)