High concentrations of micro dust appeared in most parts of the country on Monday and will remain through Tuesday, due to an influx of yellow dust from across the West Sea.

As of 12 p.m. Monday, Korea Meteorological Administration said that yellow dust has been observed covering the country nationwide including the Seoul metropolitan area. The KMA added that the southern part of the country would also see showers mixed with the yellow dust, urging people to avoid exposure to the polluted rain.

On Tuesday, between 5 to 20 mm of rain is forecast in inland and mountainous areas of Gangwon Province, North Chungcheong Province and North Gyeongsang Province, and there will be thunder and lightning along with gusts of wind in areas with showers.

The amount of airborne articulate matter smaller than 10 micrometers in diameter -- or PM 10, which can be inhaled into the lungs and has adverse health effects -- logged in "bad" and "very bad" levels in every region as of noon on Monday, according to the National Institute of Environmental Research. The institute said fine dust levels will remain at the "bad" level until Tuesday morning in the southern regions.

According to the KMA, Seoul has had yellow dust storms on 17 occasions so far this year -- the most in 20 years. One reason for the sudden increase in yellow dust is thought to be the increase in temperature and decrease in precipitation in China's Gobi Desert and Inner Mongolia Plateau, where yellow dust originates.