Beijing smog 'worst of the year'
Beijing is seeing some of the worst smog of the year, with an orange alert - the second worst level- issued over the weekend.
Pollution readings in parts of the city have reached 24 times the level considered safe by the World Health Organisation.
Under the orange weather alert mechanism, industrial plants are required to reduce or shut down production; construction sites should stop transporting materials and waste and heavy-duty trucks are banned from the roads.
The BBC's Celia Hatton stepped out in Beijing to see just how bad the air quality really is.