BEIJING, Aug. 22 -- Shanghai will take a series of measures this year to improve the quality of air inside downtown tunnels, construction officials said yesterday.

    The project will kick off on the Fuxing Road E. Tunnel and Dapu Road Tunnel. Its purpose is to reduce the density of harmful air ingredients - particularly carbon monoxide - to 40 percent of the national standard.

    "Our ultimate purpose is to create a healthy tunnel environment for drivers," said Zhang Yun with Urban Construction Maintenance Company.

    He said four major measures will soon be implemented on the Fuxing Road E. Tunnel - the country's first double-deck tunnel.

    The company will use an "intelligent system" to enhance the tunnel's ventilation fans, so they automatically adjust the level of ventilation provided depending on traffic flow.

    The interior of the tunnel will be cleaned once a week under the new plan, as opposed to the current once every two weeks.

    Tunnel managers also said they will work with traffic police to ensure cars that break down underground are towed away within eight minutes, down from the current average of about 16 minutes. "The more quickly broken-down vehicles are towed away, the less congestion the accident causes and the less emission it produces," Zhang said.

    Yan Jiting from Huangpu River Bridge and Tunnel Management Company, said the city is also planning to renovate and improve cleaning at the Dapu Road Tunnel.

    That tunnel was the city's first link under the Huangpu River and went into operation more than 30 years ago.

    Yan said when the project is finished, the company will consider improving the ventilation systems in four other tunnels depending on the level of pollution.

    Officials said most downtown tunnels have air pollution problems during rush hour, particularly the Yan'an Road E. Tunnel, although no scientific survey has been conducted on the air quality.

    Li Jianjun, a professor of environment and energy at Shanghai Academy of Science and Technology, said: "The most effective way to solve the tunnel pollution problem is to use more powerful ventilation fans."