EJ and Supplemental Indexes in EJScreen
- EJ & Supplemental Indexes
- What the EJ Index Means
- How the EJ Index Works
- What the Supplemental Index Means
- How the Supplemental Index Works
EJ & Supplemental Indexes
The EJ and supplemental indexes are a combination of environmental and socioeconomic information. There are thirteen EJ indexes and supplemental indexes in EJScreen reflecting the 13 environmental indicators. The 13 EJ index and supplemental index names are:
- Particulate Matter 2.5
- Ozone
- Diesel Particulate Matter
- Air Toxics Cancer Risk
- Air Toxics Respiratory Hazard Index
- Toxic Releases to Air
- Traffic Proximity
- Lead Paint
- RMP Facility Proximity
- Hazardous Waste Proximity
- Superfund Proximity
- Underground Storage Tanks
- Wastewater Discharge
What the Environmental Justice Index Means
An EJ index combines demographic factors with a single environmental factor. For example, the EJ index for traffic is a combination of the following populations residing in the Census block group:
- The traffic indicator
- The low-income population
- The people of color populations
Note that an EJ index does not combine various environmental factors into a cumulative score -- each environmental indicator has its own EJ index.
The EJ index is higher in block groups with large numbers of mainly low-income and/or people of color residents with a higher environmental indicator value.
How the EJ Index Works
To calculate a specific EJ index, EJScreen uses a formula to combine a single environmental factor with the demographic index (which averages low income and people of color populations).
EJScreen calculates the EJ index by multiplying together two items:
EJ index =
(The Environmental Indicator Percentile for Block Group)
X (Demographic Index for Block Group)
What the Supplemental Index Means
The supplemental indexes offer a different perspective on community-level vulnerability. The supplemental indexes use the same EJScreen methodology but incorporate a five-factor supplemental demographic index (as opposed to the two factor demographic index which averages low income and people of color populations). The supplemental demographic index averages:
- % Low Income
- % Unemployed
- % Limited English Speaking
- % Less than High School Education
- Low Life Expectancy
The supplemental demographic index is then combined with a single environmental indicator, to display areas with the highest intersection between these socioeconomic factors and the environmental indicator.
The supplemental indexes provide flexibility in the ways the data can be considered within EJScreen. They also increase EJScreen’s functionality and may be more relevant for use in certain situations, such as awarding grants.
How the Supplemental Index Works
To calculate a single supplemental index, EJScreen uses a formula to combine a single environmental factor with the supplemental demographic indicator (which averages five socioeconomic factors: low income, unemployment, limited English, less than high school education, and low life expectancy).
EJScreen calculates the supplemental index by multiplying together two items:
Supplemental Index =
(The Environmental Indicator Percentile for Block Group)
X (Supplemental Demographic Index for Block Group)