Seoul City's Health and Environment Research Institute has issued a fine dust warning as of 2 p.m. Friday.

The institute said it issued the warning after the hourly average density of fine dust particles smaller than ten micrometers in diameter, known as PM 10, was recorded over 300 micrograms per cubic meter for more than two hours.

The think tank believes yellow dust originating from the Gobi Desert in Mongolia blew into South Korea via northwesterly winds, worsening fine dust conditions here.

The Seoul city government has urged the elderly, children and people with respiratory or cardiovascular conditions to remain indoors and wear masks if they must head outside.