But the state-run Global Times said PM 10 pollution in the six downtown districts was "over 8,100" on Monday morning -- a figure which would be 160 times the recommended limit.
Officials in China have used anal swabs to test people it considers at high-risk of contracting Covid-19, including residents of neighbourhoods with confirmed cases as well as some international travellers.
Oil prices fell after days of gains fuelled by bets that slowing infections and the rollout of vaccines will boost demand down the line as economies recover.
The survey also found analysts think the COVID-19 epidemic will have a limited impact on China's property sector, and many believe the market will remain stable or further cool this year.
That stance was echoed by Lloyd Austin, who told Japanese counterpart on Saturday that the contested islands were covered by the US-Japan Security Treaty.
Hebei province, accounting for a quarter of China's total capacity, produced 229 million tonnes of crude steel in the first 11 months of last year, defying the target it set in 2018 to keep capacity within 200 million tonnes by end-2020.
The company, one of the world's biggest smartphone makers and considered China's answer to Apple, was one of 11 firms targeted by US officials who said they posed a threat to national security.
If the cold weather abates, prices may be near a peak as demand for heating fuel diminishes, traders and analysts said. Temperatures are expected to rise to above-average in Tokyo, Beijing, Seoul and Shanghai over the next few weeks, weather data from Refinitiv Eikon showed.