The Chinese city of Shijiazhuang experienced concentrations of fine particulate matter responsible for air pollution which were 100 times in excess of World Health Organisation ( WHO ) guidelines on Monday . Levels rose to 20 micrograms per cubic metre , compared to WHO guidelines of no more than an annual average of 10 micrograms . In total , over 100 cities in the northeast of the country issued yellow alerts . On Saturday, 22 cities issued red alerts, including top steelmaking city Tangshan city in Hebei and Jinan in coal-rich Shandong province. Red alerts , the highest possible warnings in relation to the Air Quality Index , were issued by 22 cities . Such alerts are more common in China ’s industrial region , largely due to the use of coal power .
The Chinese city of Shijiazhuang experienced concentrations of fine particulate matter responsible for air pollution which were 100 times in excess of World Health Organisation ( WHO ) guidelines on Monday . Levels rose to 20 micrograms per cubic metre , compared to WHO guidelines of no more than an annual average of 10 micrograms . In total , over 100 cities in the northeast of the country issued yellow alerts . Red alerts , the highest possible warnings in relation to the Air Quality Index , were issued by 22 cities . Such alerts are more common in China ’s industrial region , largely due to the use of coal power .