Another 10 percent Beijing vehicles will go off the roads if the weather is "extremely unfavorable" during the Olympic Games, the Ministry of Environmental Protection has said.

The traffic restriction already in force allows vehicles with even and odd license numbers to hit the roads only on alternate days, reducing them by half.

The emergency measure would make private cars whose last two license plate digits match the date (between August 8 and 24) to be off the roads. This could reduce the total number of private cars on the capital's roads by 60 percent.

Other emergency steps include temporarily closing 105 more factories and stopping all construction work in the city. Another 56 factories in Olympic co-host city Tianjin and 61 in Hebei province will be closed, too.

Earlier, independent experts had suggested the environmental authorities take up to 90 percent cars off the roads if the air quality does not improve during the Games.

Zhu Tong, an environmentalist advising the city government, told the Beijing News yesterday: "Though the final emergency plan will not be as effective as the one in which 90 percent cars would have been banned, the government must have considered the interests of all sides."

It's not common for Beijing to experience sultry weather like it did last week, Zhu said.

But "our independent study shows Beijing's long-term efforts have worked".

Yesterday's air pollution index (API) was 69, much healthier than what it was a couple of weeks ago, before the even-and-odd license plate number restriction was imposed. Wednesday's API was even better at 44.