Beijing's air quality readings have been at the top of Chinese President Xi Jinping's agenda in the last few days, he said on Monday, with the city desperate to keep smog under control during a prestigious meeting of global leaders.
"These days the first thing I have been doing after getting up in the morning is check how Beijing's air quality is and hope there is less smog so that all these guests from distant places will feel more comfortable", Xi said in a speech carried by China Central Television on Monday.
Determined to avoid an embarrassing spike in smog levels as US president Barack Obama and other world leaders attend the Asia-Pacific Economic Co-operation (Apec) summit, Beijing imposed the most stringent controls on traffic and industry since the 2008 Olympic Games.
Restrictions have been in place since 1 November, and since Friday, a large number of industrial facilities, such as steel mills and cement plants, within a 200km radius of the capital have been forced to shut down completely.
Beijing's official air quality index was at around 50 on Tuesday, a level described as "good". It exceeded 400, which is deemed "hazardous", in the middle of October.
However, China has ordered a popular mobile phone app, China Air Quality Index, to remove readings from a monitoring site on the roof of the US embassy in Beijing, its founder said in a post on China's popular Weibo microblogging service that was subsequently deleted.