Beijing schools have cancelled outdoor flag-raisings and taken sports classes indoors while hospitals have seen a spike in respiratory cases because of the extremely hazardous air in China's smoggy capital following a weekend of off-the charts pollution.
City authorities ordered many factories to scale back emissions, and were spraying water at building sites to try to tamp down the dust and dirt that worsens the noxious haze that has hung over the city since late last week.
Demand spiked for face masks and air purifiers, and hospitals saw surges of up to 30% in residents seeking help for breathing problems, state-run media outlets reported.
Schools in several districts were ordered to cancel outdoor activities, and in an unusual public announcement, Beijing authorities advised all residents to "take measures to protect their health".
"It's really terrible. I'm extremely upset, but there's really nothing much I can do," said a Beijing resident out for a morning stroll.
Another man, a 60-year-old pensioner, said his elderly relatives had moved to stay with family members outside the city to avoid the pollution. He said: "I'm in pretty good shape, but the older folks have a lot of problems with their hearts - breathing, and high blood pressure."
Levels of PM2.5 particle pollution over the weekend reached the highest levels since the Beijing government began publicly releasing figures early last year, and in separate monitoring by the US Embassy, they were at 886 micrograms per cubic metre in a reading that was labelled "beyond index".
By Monday, levels had declined to 245 micrograms on the Beijing government scale - down from a high above 700 - but still way above the level of 25 considered safe by the World Health Organisation.
PM2.5 are tiny particulate matter less than 2.5 micrometres in size, or about 1/30th the average width of a human hair.
They can penetrate deep into the lungs, and measuring them is considered a more accurate reflection of air quality than other methods.