All vehicles with plates belonging to other cities and provinces will be banned all day long from driving inside the Sixth Ring Road if an orange alert is issued during the conference.

Additionally, all construction sites would be required to stop demolition and other procedures that might generate dust, as required by the Beijing Commission of Housing and Urban-Rural Development, said Wang Chengjun, deputy director of the commission.

Also, if an orange alert is issued, the traffic authority will cooperate with government departments to guarantee that vehicles follow the emergency restrictions.

"The comprehensive efforts for the meeting can be an opportunity for different government departments to exercise joint work in air pollution control for the APEC meeting in November, too, and also in the future," said Yao, the deputy director of the Environmental Protection Bureau.

It is estimated that during the period there will be no extreme weather, while winds and rainfall might be slight and temperatures high, so there will be the possibility of severe air pollution in the city.

However, it's not easy to release a red alert. In the past week, the capital has witnessed mild air pollution, though in the first six months of the year in the Beijing-Tianjin-Hebei region the days with good air quality increased to 36.4 percent, according the Ministry of Environmental Protection.

Beijing has issued no red alerts on air pollution since November, when the emergency plan was put into effect, even though smog covered the city for days at a time.