In many cities and towns, pollution was 50 times and above the level recommended by the World Health Organisation (WHO).

According to state-run Global Times, pollution levels in Shenyang, the capital city of Liaoning provinces, soared to 1000 micrograms per cubic metre; WHO’s recommended level is 25 micrograms in a 24-hour cycle.

“PM2.5 concentration went off the charts in Shenyang, capital of Liaoning,” official news agency Xinhua said.

“Density of PM2.5, airborne particles smaller than 2.5 microns in diameter, reached extremely high levels across the region, slashing visibility, grounding flights and closing highways,” it said.

“The air-quality index (AQI) in six cities in Liaoning province exceeded the maximum of 500 on Sunday. Eight of the 14 cities were still labeled as ‘seriously polluted’ on Monday,” it added.

On Monday, the maximum hourly reading for PM2.5, airborne particles smaller than 2.5 microns in diameter, hit 860 micrograms per cubic meter in Changchun, capital of Jilin.

The rapid rise in pollution has coincided with the government switching on the central heating system as winter sets in.

“Such a dangerous level of acrid smog shocked the public and the media were quick to point out the failure to enact local emergency measures to protect the public. Many local residents were reportedly not informed of the density of the harmful particulates and the website of the Shenyang Environmental Protection Bureau broke down for nearly two hours on Sunday,” the Global Times editorial said.

There is no respite in sight.

The Ministry of Environmental Protection has said China’s northeast region will be covered in heavy smog till the end of this week.

“Most areas in Liaoning, Jilin and Heilongjiang provinces will see medium to heavy air pollution from Nov. 10 to 14, with PM2.5 being the main pollutant,” the statement said.