To move towards sustainable development in practice, decisions must be evaluated and modified in light of its principles. For the planned Hong Kong-Macau-Zhuhai bridge, the governments involved should first evaluate the environmental sustainability of accelerating development of the western Pearl River Delta. The bridge project should only be given the go-ahead when ways of reducing pollution elsewhere have been identified - and implemented. More than just a road link, the bridge is intended to open up the western delta to industrial expansion and to entice cargo shipments via Hong Kong. While the growth of Hong Kong's economic hinterland is appealing, we need to ask how this added development can be made environmentally sustainable. The delta's air quality is bad, and getting worse. Even by our own rather lax air-quality objectives, we now breathe pervasively unhealthy air. For more and more of the year, the air we share with the rest of the delta is well beyond its capacity to absorb the current pollutant loads. As bridge proponents argue, there is about a three-hour driving-time limit from Hong Kong that local entrepreneurs use for locating their factories. In the eastern delta, Dongguan is about at this limit. A bridge to Zhuhai and Macau would open up similar opportunities for development to Zhongshan, and with new highways, to Shunde or beyond. Satellite photos of the delta show that the western side is relatively green today, whereas the eastern area is built up, generating much of the air pollution. The bridge would roughly double the size of Hong Kong's industrial hinterland. Today, there are between 40 and 50 million people living and working in the delta. With the opening up of the west, this could easily increase by 20 per cent. Even if all the extra 10 to 15 million people are engaged in relatively clean manufacturing practices, their sheer numbers will increase demand for electricity, transport and other energy-intensive (and potentially polluting) activities. We are already choking at the present levels of population and economic activity. How are we to accommodate these new emissions? The Hong Kong and Guangdong governments need to develop an up-to-date emissions inventory, including a detailed assessment of the quantity and quality of the fuel being used for backup power generation by individual factories. Once we know the details of the emissions, we should cap them (for now) and allow the financing and construction of the bridge to go ahead only when we have implemented measures to combat air pollution elsewhere in the delta. The inventory will help prioritise matters. A prime area for action would appear to be the inadequate power generation capacity in Guangdong. As a result, tens of thousands of factories upwind of Hong Kong employ their own, inefficient power generators. This is made worse by the use of low-quality fuel. In fighting air pollutants, improvements in fuel quality are a highly cost-effective first step. An improvement closer to home would be a greater reliance on natural gas for Hong Kong's power generation. Indeed, an important part of the long-term solution is a more natural-gas-intensive energy economy for the delta, supported by more and larger liquefied natural gas terminals. We need to work with Guangdong to reduce pollutant emissions in the delta. Sustainable solutions will not come overnight, but if we fail to make the financing and construction of the bridge conditional, it is unlikely that we will again enjoy relatively clean air in our lifetime, or even in our children's. Bill Barron is an associate professor in the Centre of Urban Planning and Environmental Management at the University of Hong Kong. Paul Zimmerman is principal of The Experience Group, a policy and strategy consultancy, and convenor of Designing Hong Kong Harbour District
