Environmental Justice Indicators

Environmental Justice Indicators

NC ENVIROSCAN contains information from the US Environmental Protection Agency (USEPA) in the form of environmental justice (EJ) indices. 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 minority population

Note that an EJ index does not combine various environmental factors into a cumulative score — each environmental indicator has its own EJ Index.

To calculate a single EJ Index, EJSCREEN uses a formula to combine a single environmental factor with the demographic indicator. It considers how much the local demographics are above the national average. It does this by looking at the difference between the demographic composition of the block group, as measured by the Demographic Index, and the national average (which is approximately 35%). It also considers the population size of the block group, although most block groups are similar in population size.

EJSCREEN calculates the EJ Index by multiplying together three items:

EJ Index = (The Environmental Indicator) × (Demographic Index for Block Group − Demographic Index for US) × (Population count for Block Group)

The EJ Index is higher in block groups with large numbers of mainly low-income and/or minority residents with a higher environmental indicator value.

Exposure to environmental contaminants can result in negative health outcomes. Certain populations are more vulnerable to effects of these environmental exposures and may be more likely to experience adverse health outcomes. The EJ index data provided by USEPA allows users to map each environmental factor along with the block groups that contribute the most toward the nationwide disparity in that environmental factor. By "disparity" in this case we mean the difference between the environmental indicator's average value among these demographic groups and the average in the US population.

There are eleven EJ Indexes in EJSCREEN reflecting the eleven environmental indicators that are mapped in EJSCREEN. We have added all eleven to the ENVIROSCAN mapping tool. The eleven EJ Index names are:

  • National Scale Air Toxics Assessment Air Toxics Cancer Risk
  • National Scale Air Toxics Assessment Respiratory Hazard Index
  • National Scale Air Toxics Assessment Diesel PM (DPM)
  • Particulate Matter (PM2.5)
  • Ozone
  • Lead Paint Indicator
  • Traffic Proximity and Volume
  • Proximity to Risk Management Plan Sites
  • Proximity to Treatment Storage and Disposal Facilities
  • Proximity to National Priorities List Sites
  • Wastewater Discharge Indicator

For more information about EJSCREEN and the EJ Index scores, please visit the USEPA EJSCREEN website.

In ENVIROSCAN, the EJ Index data is mapped by census block group.

Please Note: Since these EJ indices already combine demographic and environmental indicator information, these layers are best viewed on the single map view that does not allow layering with other indicators.

These are the 2020 data retrieved from the USEPA’s EJScreen website.