Air quality is an ongoing concern in Hong Kong, especially for people who live, work or walk near heavily congested streets.
Some measures have been taken to improve the city’s air quality. A recent government proposal to replace older diesel engines in buses and commercial goods vehicles with cleaner ones is one such example.
However, this is not the end of the story. Research conducted in Central by City University’s School of Energy and Environment has found that vehicle emissions are not the only cause of poor air quality. Buildings, surprisingly, play an important role in shaping roadside air quality.
In the chart, figures showing air pollution levels on various streets are seen as the dotted line while the hourly traffic volume is the height of the bar. As you can see, Connaught Road Central has 10 times more traffic than Des Voeux Road Central and Queen’s Road Central. But the pollution levels in Des Voeux Road Central are two to three times higher than the other two roads.
This seemingly contradictory phenomenon is actually driven by the buildings along different streets. For example, Des Voeux Road Central is characterised by high-rise buildings and narrow roadways that create a “canyon” effect, which traps vehicle pollutants.
So what can we do? Other cities have solved similar problems using smart traffic control. Beijing recently proposed a ventilation corridor that would facilitate the dispersion of pollutants.
Hong Kong is famous for its vertical city landscape, but it may be time for us to rethink how we should use our urban roadways to produce optimal traffic flow while reducing air pollution.