Beijing is considering taking further measures to try to reduce the city's polluted air before the Olympic Games.  Chinese authorities have already taken drastic steps, but with little visible progress.  Daniel Schearf reports from Beijing.

China's state media reports Beijing may have to put in place an "emergency green plan" to try to quickly reduce the city's air pollution in time for the Games.

The official China Daily newspaper said the plan being considered would stop all construction in the city and neighboring areas, shut down more factories, and pull more vehicles from the streets.

Despite the emergency plan, Chinese officials are still painting an optimistic picture of expected air quality during the Olympic Games.

Du Shaozhong, deputy director of the Beijing Environmental Protection Bureau, says with the progress and information they have collected so far, they feel they can assure good quality air for the Olympics.  More importantly, he says, the International Olympic Committee and relevant health organizations have also come to a conclusion the air quality situation in Beijing will not affect the health of the athletes.

Beijing has already taken draconian measures to try to clean up its air. 

The city has moved entire factories from central areas to the edge of the sprawling metropolis and banned more than 300,000 heavy-polluting trucks from entering the city.  Many factories and construction sites have also been temporarily closed.

In its most dramatic move to date, the city last week cut the number of private cars allowed on the road in half, by limiting drive time to odd and even days according to license plate numbers.

But, Beijing's air has shown little visible improvement and, in the past few days, air quality appeared to get worse.

"Greenpeace believes that with the current performance of air quality in Beijing, the IOC, the Beijing Olympic Organizing Committee, and also sports teams from various countries have reason to be concerned with the situation," said Lo Sze Ping, a spokesman for Greenpeace China.

Many Olympic athletes have chosen to train in other countries or cities before the August games to avoid Beijing's pollution.

The capital of China is one of the most polluted cities in the country and is often shrouded in a thick, gray haze fed by burning coal and factory and vehicle emissions.

Beijing has almost 3.5 million cars and every day 1,000 more vehicles are added to the streets.

The China Daily quoted an environmentalist who suggested up to 90 percent of private vehicles should be kept off the streets during the Olympics.  It is not clear if the suggestion would be part of the emergency plan.