The severe air pollution in China has hit alarming levels, with recent reading of atmospheric particulate matters (PM2.5) hitting up to 20 times the safe limit of 25.
AFP reports said that PM2.5 concentration in Hebei province has reached 500 micrograms per cubic meter, while that in the Beijing capital is above 300.
The China Meteorological Administration has issued the second-highest alert level called "orange" alert.
"Heavy fog with visibility of less than 500 meters" continues to shroud some parts of Beijing, western Tianjin, central-western Hebei and southern Henan, said the CMA on Friday.
Officials are advising schools to avoid outdoor activities and physical exercise classes. Also, elderly and people with heart and lung problems have been advised to remain indoors.
Meanwhile, in response to escalating public distress, the national government has issued a "war on pollution," saying that efforts will be made in order to allay the situation.
With China's Beijing capital as host to the upcoming APEC summit in November, the government is pressed to resolve pollution in the affected cities by reducing coal use, implementing a coding ban for vehicles and requesting adjacent areas to close polluting establishments.
"Beijing will make every effort to prepare for the APEC meeting and we need to control air and water pollution," said Guo Jinlong, Communist Party Chief and former mayor of Beijing.
Studies conducted by the World Bank, WHO and the Chinese Academy for Environmental Planning suggest that the severe air pollution in China kills a quarter to half a million Chinese every year, making it the "fourth biggest threat to the health of Chinese people."