An air quality advisory was issued across the country on Tuesday as Korea was hit with yellow dust blowing from inner China, along with heavy snow advisories, raising concerns over public health safety.

The Ministry of Environment raised the yellow dust advisory level in Seoul, Gwangju, Gangwon and North Jeolla Province from "attention" to "caution" as of 7 p.m. on Tuesday. Incheon and Gyeonggi Province was issued a "caution" level advisory from 7 a.m. the same day. Except for Southern Gyeongsang Province, all regions outside the metropolitan area were under the "attention" level advisory.

The “caution” level is issued when the hourly average concentration of PM10 -- ultrafine dust smaller than 10 micrometers in diameter -- surpasses 300 micrograms per cubic meter for more than two hours. The “attention” level advisory is issued when the average daily concentration of PM10 exceeds 150 micrograms per cubic meters.

The Institute of Health and Environment under the Seoul city government said that yellow dust coming from the Gobi Desert and the inner Mongolia plateau region flowed along with the northwestern wind, increasing the concentration of fine dust.

The institute urged citizens, especially the elderly, children and people with respiratory or cardiovascular diseases to refrain from going out, and encouraged everyone to wear masks.

The National Institute of Environmental Research predicted that ultrafine dust levels across the country will return to normal on Wednesday.

Also, as of 2 p.m. Tuesday, the Ministry of Public Administration and Security said it will operate the Central Disaster and Safety Countermeasures Headquarters, as heavy snow advisories were issued mainly in southern Gyeonggi, Chungcheong, North Jeolla, and southern Gangwon provinces.

More than 10 centimeters of snow will fall in southern Gyeonggi, southern Gangwon and northern Chungcheong provinces until Wednesday, while Chungcheong, North Jeolla provinces and the easternmost islands, Ulleung island and Dokdo, will see about 5 centimeters of snow.