Data for: Urban form and its impacts on air pollution and access to green space: A global analysis of 462 cities

A better understanding of urban form metrics and their environmental
outcomes can help urban policymakers determine which policies will lead to
more sustainable growth. In this study, we have examined five urban form
metrics – weighted density, density gradient slope, density gradient
intercept, compactness, and street connectivity – for 462 metropolitan
areas worldwide. We compared urban form metrics and examined their
correlations with each other across geographic regions and socioeconomic
characteristics such as income. Using the K-Means clustering algorithm, we
then developed a typology of urban forms worldwide. Furthermore, we
assessed the associations between urban form metrics and two important
environmental outcomes: green space access and air pollution. Our results
demonstrate that while higher density is often emphasized as the way to
reduce driving and thus PM2.5 emissions, it comes with a downside – less
green space access and more exposure to PM2.5. Moreover, street
connectivity has a stronger association with reduced PM2.5 emissions from
the transportation sector. We further show that it is not appropriate to
generalize urban form characteristics and impacts from one income group or
geographical region to another, since the correlations between urban form
metrics are context specific. Our conclusions indicate that density is not
the only proxy for different aspects of urban form and multiple indicators
such as street connectivity are needed. Our findings provide the
foundation for future work to understand urban processes and identify
effective policy responses.