URBAN REVITA LISAT ION

Curbing emissions at their source is paramount in the quest for clean air, but better urban planning is vital to stop pollution concentrating in the city’s most populous areas. With 40 per cent of Hongkongers living above the 14th floor, we have “avoided the blight of urban sprawl,” says Shaw, but we suffer the consequences of an extremely dense urban environment. Close-packed high-rise buildings and narrow streets trap fumes in a phenomenon known as the “street canyon effect.” This is compounded by the “heat island effect,” whereby the concrete jungle absorbs heat from the sun (and engines) by day and radiates it by night, increasing nighttime temperatures. This drives up demand for air conditioning and thereby electricity. Encouraging low-rise buildings, establishing more pedestrian zones, rationalising bus routes and creating cycling lanes would increase ventilation, while urban greening— planting vegetation at street level as well as in roof and wall gardens—would help filter out pollutants and cool the air through shade and transpiration. Energy-efficient buildings would also decrease electricity use and reduce emissions from power plants.