Thursday, October 23, 2014

Which Approach to Urban Development reduces Air Pollution the most - Intensification or Greenspace?

Effects of Compact Urban Development on Air Pollution: Empirical Evidence from Korea (15 page pdf, Hee-Sun Cho and Mack Joong Choi, Sustainability, Sep. 5, 2014)

 Today we review research aimed at finding out whether a concentration of the urban population in a city core and reducing the need for traffic emissions is the better option for improved air quality than developing urban areas with lots of greenspaces which offer a way of diluting the air pollution concentration across the urban area. The examination including looking at five major air pollutant measurements in 17 cities in Korea, as well as assessing dilution using air quality dispersion modeling. Results are inconclusive in terms of these two options. More important to improved overall air quality is finding ways to reduce individual emission  sources.

 urban development- korea  

Key Quotes:

 “urban sprawl …leads to loss of green open spaces and an increase in traffic and energy consumption…the compact city concept has been put forward as a form of sustainable urban development. Air pollution is one of the key environmental problems associated with urbanization.”

 “Compact urban development would likely have both positive and negative effects on air quality:
  • "high-density development can result in reduced car dependency, reduced energy consumption, and low emissions via a decrease in distance traveled
  • Higher densities lead to traffic congestion and greater air pollution …Large cities pollute more and generate more environmental damage than medium-sized ones
  • Atmospheric dispersion and dilution of air pollutants are strongly influenced by meteorological conditions and topographical features, and urban structures have a great effect on meteorological parameters such as wind direction, wind speed, turbulence, and atmospheric stability”
“NO2 and CO increased as the net population density increased, implying that compact urban development can result in greater spatial concentration of pollutants. On the other hand, SO2 and CO decreased as the proportion of green areas increased, implying that green areas secured by compact development can promote the dispersion of pollutants and thereby mitigate air pollution…urban compactness did not have a significant effect on PM10 and O3.”

“compact urban development does contribute to a rising proportion of green areas, then such a development is helpful in mitigating air pollution.”

 “there is a need to differentiate in regard to whether emission sources are concentrated at the local or regional level and to develop an integrated management system that minimizes local to citywide emissions and thus regulates total urban emissions.”

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