Beijing is notoriously polluted, the haze often obscuring buildings
All building sites in Beijing will be shut three weeks before the start of the Olympic Games, as the city tries to clear its skies of pollution.
Digging, pouring of concrete and outdoor spray-painting will also be banned under plans announced by the Environmental Protection Bureau.
The move follows mounting concern that athletes may suffer from Beijing's noxious atmosphere.
Olympic chiefs have already voiced concern over the issue.
President of the International Olympic Committee Jacques Rogge had previously warned that he would postpone certain endurance events if pollution levels were excessive.
When Beijing bid for the Olympic Games in 2001 it promised to provide a clean environment for the athletes by August 2008, when the Games open.
But the BBC's James Reynolds, in Beijing, says the air in the city is often astonishingly bad and the city authorities have found this promise tough to keep.
Our correspondent says there are days when it is hard to see more than a few blocks away.
So on 20 July all construction sites in Beijing will be shut down - as well as cement manufacturers and concrete mixing plants.
And 19 businesses have been told to cut their emissions by 30%.
Officials say they will announce steps to take cars off the city's roads and have pledged to do "everything possible" to honour their promise to provide a clean atmosphere.