The yellow dust advisory level in Seoul was raised from the lowest "attention" to the second-lowest "caution" as of 10 a.m. Tuesday, following similar elevations for Incheon and Gyeonggi Province three hours earlier.

The increase to the second level in the four-tier system came after conditions met the criteria in the capital, with a fine dust warning activated due to a particle density of yellow dust of 300 micrograms per cubic meter per hour for two hours or longer.

The lowest "attention" tier is in place for areas outside the capital region, with the exception of South Gyeongsang Province, indicative of an daily average density expected to surpass 150 micrograms per cubic meter.

The yellow dust that began to blanket the country on Monday night originated from China's Gobi Desert and Inner Mongolia Plateau.

The National Institute of Environmental Research forecast density levels nationwide to return to normal by Wednesday.