The Chinese capital city of Beijing issued its second-ever red alert for dangerous acrid smog as it urged citizens to stay indoors, China's state media reported Friday.

The red alert, the most serious warning for air pollution, forecast that severe smog will blanket Beijing for three days starting Saturday morning.

Beijing, notorious for its severe air pollution, issued its first-ever smog red alert earlier this month, closing schools and curbing production at factories.

China regularly sees hazardous air pollution with levels of particulate matter rising to nearly 40 times the limits set by the World Health Organization during the winter when Chinese homes and plants burn huge amounts of coal for heating.

The levels of air pollution in South Korea have also been jumping during the winter months, as westerly winds carry the smog from China to the Korean Peninsula. (Yonhap)