0750 GMT October 23, 2019
At least 23 cities in the world's most populous nation have issued red alerts for air pollution since Friday, according to Xinhua.
A host of emergency measures have been implemented to protect the public's health from the smog, which is smothering almost a ninth of the entire country.
On Monday evening – the fourth day of the alert which is scheduled to end on Wednesday – Beijing's air quality was better than feared, with PM 2.5 levels hovering around 200.
The Ministry of Environmental Protection said anti-pollution measures, such as temporary factory closures and taking half of cars off the roads, accounted for the better-than-expected numbers.
But the figure remained eight times the World Health Organization's daily recommended maximum exposure level to the microscopic particles that carry major health risks.
And the relatively low number was just a temporary reprieve, Beijing's meteorological authority told AFP, adding that the worst haze would hit the city Monday night and linger until Tuesday.
In neighboring Shijiazhuang, the capital of Hebei Province, PM 2.5 levels stood as high as 701 at noon, with levels of larger PM 10 particles even higher.
In the port city of Tianjin, where readings for PM 2.5 climbed over 400 early in the morning, more than 131 flights were canceled and around 75 delayed Monday morning, according to Xinhua.
Highways in the city were also closed, it said.
Several large hospitals in Tianjin saw a surge in the number of patients with respiratory diseases such as asthma, according to the People's Daily.
A red alert, issued when severe smog is expected to last more than 72 hours, is the highest of Beijing's four-tiered, color-coded warning system.
Most of China's smog is blamed on the burning of coal for electricity and heating, which spikes when demand peaks in winter.