Air & Water Quality – Air Toxics Respiratory Hazard Index
This indicator reports the respiratory Hazard Index (HI) from the analyzed carcinogens in ambient outdoor air. The HI is the sum of hazard indices for those air toxics with reference concentrations based on respiratory endpoints, where each hazard index is the ratio of exposure concentration in the air to the health-based reference concentration set by EPA. Areas with higher air toxics respiratory HI levels (i.e., more harmful to human health) are placed higher in percentile (national ranking). The percentile could be interpreted as, for example, for a place at the 80th percentile nationwide, 20% (i.e., 100 minus the percentile) of the U.S. population lives in a block group that has a higher value.
The EJ Index for Air Toxics Respiratory HI is a combination of this environmental indicator and the Demographic Index (the average of percent low-income and percent people of color).
Data are acquired from EPA’s EJScreen dataset, 2022.
Source
Source Description
EJScreen is an EPA’s environmental justice mapping and screening tool that provides EPA with a nationally consistent dataset and approach for combining environmental and demographic socioeconomic indicators. An EJ index combines demographic factors with a single environmental factor. For example, the EJ index for traffic proximity is a combination of the following populations residing in the Census block group:
- The traffic proximity 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.
For more information, please visit the EJScreen website.
Methodology
This indicator reports the respiratory hazard index (HI) from the analyzed carcinogens in ambient outdoor air. It is a measure of air toxics risk, as opposed to exposure. The raw air toxics respiratory HI data is provided by the 2017 Air Toxics Data Update (EPA OAQPS) at the census tract level. The tract values are re-assigned to each block group, so all block groups within each tract have the same air toxics respiratory HI value as for the tract. CARES estimated the values for all other geographic levels using total population (ACS 2018-22) and the technique of Population-weighted Small Area Estimate.
The percentile in EJScreen is reported as what percent of the U.S. population lives in a block group that has a lower value (or in some cases, a tied value).
The relevant EJ Index is calculated as:
where Normalized Environmental Indicator is the percentile of the particular environmental indicator source data.
For more information about this indicator or the methodology of EJScreen, please refer to the EJScreen Technical Documentation.
This indicator is available at the following subscription levels:
- Premium (currently viewing this indicator and report combination)