China activated Saturday an orange alert, the most serious warning after a red alert, because of the dangerous pollution levels registered in the northern, central and eastern parts of the country that have forced expressways to close and flights to be either delayed or canceled.

The Chinese Meteorological Center this Saturday raised the alert level to orange along the east coast of the country including Jiangsu, Zhejiang, Anhui and the Shanghai metropolitan area, in the central region including Henan, and in the north where the nation's capital Beijing is located.

Despite the alert, the Center said the situation will improve between Saturday and Wednesday, thanks to the approaching cold front accompanied by strong winds, which will help cleanse the air while causing a drop in temperatures.

Saturday's severe pollution caused the temporary closure of about 100 expressways in eastern China and a number of flight cancellations or delays at airports in the coastal cities of Qingdao and Jinan, both in the eastern province of Shandong.

The regions of Jiangsu, Zhejiang and Henan have suffered six days of suffocating air pollution, while Shanghai, the economic capital of China, reached such critical levels on Friday that official vehicles were forced off the streets, construction works were suspended and children were not allowed outdoors.

The concentration of fine particles known as PM 2.5, the most dangerous to health because they can infiltrate the lungs, rose to more than 600 micrograms per cubic meter in Shanghai on Friday, the highest level since the city began taking those measurements last December, while on Saturday it dropped to the still dangerous level of 200.

The World Health Organization, or WHO, recommends a concentration no higher than 25 micrograms per cubic meter.

Pollution is one of the grave consequences of China's rapid development. EFE