The Environmental Neighborhoods of Cities and Their Spatial Extent

We define the new concept of an environmental neighborhood as the surrounding area influencing the environmental quality at a given point in a city, and we develop a method to measure its extent. The analyses are illustrated for the air quality dataset from NYCCAS collected from 2008-2016 at 150 air quality stations. The urban parameters are compiled from the New York City land-use dataset at 3ft resolution, the NYC Open data GIS dataset, the NYC PLUTO dataset for building and lot information, and the NYC traffic dataset for the year 2012-2013. While the spatial extent of the environmental neighborhoods might change for different cities, the concept and methodology are generalizable and the data we use are becoming increasingly available for many cities around the world to replicate our analyses.

The results show that urban fabric and activity parameters associated with building morphology and building use play the most critical role in determining the spatio-temporal gradients of air quality. A variable footprint analysis indicates that this role is exerted most significantly at scales that range from ~ 1000m (for attributes such as road area or building footmark) down to ~ 200m (for building use or green area), allowing us to measure the extent of the “environmental neighborhoods”. The results illustrate that selecting this optimal neighborhood scale is critical for finding robust relations between air quality and urban attributes, and thus for air quality modeling. Smaller footprints do not contain all the pertinent urban surface information, while larger footprints contain irrelevant, potentially misleading information. This enables more effective and localized policies and interventions to improve urban environmental quality and reduce urban health disparities.