The crisis alert for yellow dust was raised a notch to "caution" on the four-tier scale as dust particles continue to enter the country's atmosphere from China.

The environment ministry said the adjustment was made as of 7 a.m. Wednesday, as the average density of particulate matter smaller than ten micrometers in diameter in 17 major cities and provinces stayed over 300 micrograms per cubic meter for two hours.

The four-scale warning system for yellow dust climbs from “attention” to “caution,” “alert” and “serious.”

Upon the elevation, the ministry began the operation of an integrated situation room and requested relevant institutions and municipal governments to respond in accordance with guidelines.

The Korea Meteorological Administration(KMA) forecast the yellow dust from China's Gobi Desert, Inner Mongolia plateau and Manchuria to blanket the nation through Thursday.

Authorities have advised seniors and people with underlying respiratory conditions to refrain from outdoor activities, while recommending that everyone wear a mask when going outside and wash their hands and feet after returning home.