Heavy smog blanketed the Chinese capital Friday, but authorities did not declare a third red-level pollution alert.
The level of fine particulates hit the officially "dangerous" level of 500 microgrammes per cubic metre, according to the environmental group World Air Quality Index.
The maximum safe level is 25 microgrammes, according to the World Health Organization.
Beijing has issued two red smog alerts this month, for the first time under a colour-coded system implemented in 2013.
But city authorities on Friday did not issue another warning, which would have closed schools and factories and restricted traffic for three days.
A north wind was forecast to blow the latest smog away from the region Saturday.
Heavy smog is common in the winter months in northern China, where coal is widely used.