Twenty-four heavily polluting and water-consuming firms have been closed or have had their operations suspended since early last year to ensure clean air during the Beijing Olympic and Paralympic Games, an official said Thursday.

These firms produced cement, glass, paper, chemical products, or were involved in casting, printing, dyeing and electroplating industries.

With the closure of the firms, energy equivalent of 123,000 tons of standard coal and 3.248 million tons of water will be saved every year. The move will also help reduce exhaust gas emission by 480 million cu m and solid waste by 40,000 tons every year.

Authorities are stepping up efforts to ensure a green Games from this month.

"On July 1, we adopted a policy curbing the operation of high-emission vehicles in urban areas and removing certain government cars from the roads," Du Shaozhong, vice-director of the Beijing municipal environmental protection bureau, said.

"We will persist with carrying out all of these measures. Air quality has been better over the past few days than in the same period of last year, and this is partly due to our emissions-reduction efforts."

Beijing made three commitments in its bid to host the Olympics: It would monitor daily air quality through the collection of data; it would improve air quality every year; and it would reach a satisfactory air-quality standard by the beginning of the Games.

"Through our long-term efforts, the first two commitments have been fulfilled," Du said. "As for the third, I believe that with the measures we are taking and those we will take, the air qualify during the Games will be satisfactory."

Since 1998, Beijing has introduced more than 200 measures in 14 phases to reduce emissions from vehicles, coal plants and industry.

A new series of measures will go into effect from July 20 to Sept 20.

In Beijing, they include the suspension of construction work and the requirement of drivers to abide by an odd-and-even license plate scheme that allows them to drive only on alternate days.