The government will not seek the chief executive's approval for waiving air-quality requirements when building the proposed bridge from Hong Kong to Macau and Zhuhai, officials stressed yesterday. In response to concerns that the bridge project would worsen Tung Chung's air pollution problem, the Environment, Transport and Works Bureau said it would mitigate any impact and not seek an 'exceptional way' to avoid restrictions. It is understood that highway officials are considering the cost implications and environmental benefits of at least four road networks connecting to the bridge after it lands in San Shek Wan, north Lantau. Two of the more expensive options are building tunnels under the sea or cutting across the hills to bypass Tung Chung before the road chosen connects with the North Lantau Expressway. But Tung Chung might suffer more disturbances from two cheaper options that divert traffic from the bridge to the fringe of the new town or a viaduct over the sea off the town. It was reported yesterday that nitrogen oxide levels at Tung Chung might reach up to 400 micrograms per cubic metre on an hourly basis under the worst traffic scenario when the bridge is completed. The level is one third over the acceptable level of 300 micrograms under existing air quality objectives. Nitrogen oxide is a gas pollutant that can react with volatile organic compounds to form ozone. In September last year, Tung Chung new town was hit by the worst ozone pollution that pushed the air pollution index to a record high of 201. Under the Environmental Impact Assessment Ordinance, the government can seek the chief executive's approval to exempt a works project from air quality requirements on the grounds of public interest. Esmond Lee Chung-sin, deputy director of environmental protection, said the project's environmental impact assessment was continuing. An Environment, Transport and Works Bureau spokesman said: 'We'll fully comply with the requirements of the ordinance and other relevant statutory requirements. Seeking an exemption from the Executive Council under the EIA Ordinance is not a consideration. While a preferred landing point at San Shek Wan has been identified, the alignment of the road connecting the bridge from its landing point to the local highway network is still being examined and no decision has been made.' Hahn Chu Hon-keung, environmental affairs manager of Friends of the Earth, warned that the bridge might worsen North Lantau's air pollution problems.