λ VPI refers to EDN's Vulnerable Population Index. All cities have vulnerable populations. However, in some U.S. cities the concentration of citizens at risk is of particular concern. Earth Day Network’s Vulnerable Population Index (EDN VPI) is a measure suggesting what portion of a city's population may have greater sensitivity or susceptibility to environmental change. The ‘VPI Rank’ options above will provide Subject Area scores weighted by VPI and corresponding rank information for each city in the report.
4 SITES is an acronym developed by EDN as a summary for the 'Safety, Income, Transportation, Education & Sprawl' Subject Area.