EJSCREEN: Environmental Justice Screening and Mapping Tool

Frequent Questions about EJSCREEN


What is EJSCREEN?

EJSCREEN is an environmental justice screening and mapping tool that utilizes standard and nationally-consistent data to highlight places that may have higher environmental burdens and vulnerable populations. The tool offers a variety of powerful data and mapping capabilities that enable users to access environmental and demographic information, at high geographic resolution, across the entire country; displayed in color-coded maps and standard data reports. These maps and reports show how a selected location compares to the rest of the nation, EPA region or state. The tool also combines environmental and demographic indicators to create EJ indexes.

Top of Page


What is an EJ Index?

An EJ Index is a way of combining demographic information with a single environmental indicator – such as proximity to traffic – that can help identify communities that may have a high combination of environmental burdens and vulnerable populations.

Top of Page


Why is EPA creating an EJ screening tool?

EJSCREEN helps EPA meet the intent of Executive Order 12898, "Federal Actions to Address Environmental Justice in Minority Populations and Low-Income Populations," to focus federal attention on the environmental and human health conditions of minority and low-income populations with the goal of achieving environmental protection for all communities. An important first step to ensuring environmental justice for all people in this country is to identify the potential areas where people are most vulnerable or likely to be exposed to different types of pollution. For this reason, EPA developed EJSCREEN to help aid in efforts to ensure programs, policies and resources are appropriately inclusive and consider the needs of communities most burdened by pollution.

Top of Page


How does EPA use EJSCREEN?

EPA uses EJSCREEN to identify areas that may have higher environmental burdens and vulnerable populations as the Agency develops programs, policies and activities that may affect communities. A few examples of what EJSCREEN supports across the Agency include:

  • Informing outreach and engagement practices;
  • As an initial screen for voluntary programs, enhanced outreach in permitting, and prioritizing enforcement work;
  • Developing retrospective reports of EPA work; and
  • Enhancing place-based activities.

EJSCREEN is not used by EPA staff for any of the following:

  • As a means to identify or label an area as an “EJ community;”
  • To quantify specific risk values for a selected area; or
  • As the sole basis for EPA decision-making or making a determination regarding the existence or absence of EJ concerns.

Top of Page


Does EPA use any filters as a part of the screening process?

In past screening experience, EPA has found it helpful to establish a suggested Agency starting point for the purpose of identifying geographic areas that may warrant further consideration, analysis or outreach. The use of an initial filter promotes consistency and provides a pragmatic first step for EPA programs and regions when interpreting screening results. For early applications of EJSCREEN, EPA identified the 80th percentile filter as that initial starting point. As EPA gains further experience and insight into the performance of the tool and its applicability for different uses, program offices and regions may opt to designate starting points that are more inclusive or specifically tailored to meet programmatic needs more effectively. Read the EJSCREEN Technical Documentation for more information on this topic.

Top of Page


What are EPA's expectations for how and when stakeholders and partners use EJSCREEN?

EPA is sharing EJSCREEN with the public in part to be more transparent about how the Agency consider environmental justice in our work. There is no mandate or guidance expressed or implied that regulatory agencies at the tribal, state or local level should use the tool or its underlying data. EPA will work with all stakeholders interested in using EJSCREEN, and encourages all users of the tool to provide feedback to us about their needs and concerns related to the tool.

Top of Page


Can EJSCREEN be used as the basis for an official EPA decision?

No. Consistent with E.O. 12898, EJSCREEN uses environmental and other data sets to help identify areas that may warrant further consideration, analysis, or outreach and to help ensure that they are not overlooked in making decisions based on human health and environmental considerations. However, EJSCREEN is a pre-decisional tool and is not intended or designed to provide definitive determinations about the presence or absence of EJ concerns in any given location.

In part, this is because EJSCREEN, like any screening tool, has some significant limitations. For example, because of the need to provide national consistency, EJSCREEN considers a limited number of environmental indicators, and therefore excludes some local, state, regional and national data sets that may be important to understanding the EJ characteristics of a given location. Other limitations are discussed in greater detail in the technical documentation. All such relevant data should be considered when it is applicable and available.

Top of Page


What were the criteria for including the environmental indicators?

The environmental indicators included are those for which there are national, publically-available data at a sufficient geographic resolution. Other types of information, either not available at the appropriate spatial resolution (e.g., radon), or not available nationwide (e.g., local health data) could be overlaid on top of EJSCREEN maps by adding the relevant geospatial data layers.

Top of Page


How Do EJSCREEN Results Compare to Other Datasets?

EJSCREEN is limited in the types of data it can collect because it is a national-level screening tool, and its outputs should be one part of a screening process which also incorporates local knowledge and data such as might be found in other tools. EJSCREEN results are not meant to replace or supersede the use of other federal, state or local tools or their underlying data. Different tools and datasets deploy different methods and timeframes for collecting data, and thus the results should not be compared. For example, the air quality data in EJSCREEN is national in coverage and relies on one approach to combining monitored and modelled data. Different approaches may vary substantially.

Top of Page


Why are some datasets older than others?

EPA is committed to updating EJSCREEN annually as new datasets for existing EJ indexes becomes available. The process for collecting data from across the country, modelling it, and inserting it into EJSCREEN takes time, and therefore EJSCREEN will never be entirely up-to-date. Also, some datasets, like NATA, are updated less frequently. Any national screening tool will reflect a picture of the air quality of a community that is not entirely accurate. This is an inherent characteristic for a screening tool, and thus is one of the reasons it is not used to make EPA regulatory decisions.

Top of Page


Does the tool account for cumulative or synergistic impacts?

EJSCREEN is a screening tool that offers a way to compare specific places across 11 different environmental indexes that represent different types of impacts. However, the tool is not designed to take into account quantifiable cumulative or synergistic effects.

Top of Page


Why do you only consider proximity to a facility and not emissions or risk from that facility?

EJSCREEN does include some risk estimates, for example, the National Air Toxics Assessment cancer risk, but these are aggregated risks from many sources that do not represent risk estimates for individual facilities. EJSCREEN also includes some environmental indicators highlighting potential exposure (e.g., ambient concentrations of PM2.5 and ozone (O3)). EJSCREEN uses distance weighted proximity as a proxy for the potential impact of specific types of facilities. Site-specific risk estimates would require much more data and analysis, beyond what could be reasonably be included in a national screening tool.

Top of Page


Why do only certain types of sites have a proximity measure?

The intent of the proximity measures is to include facilities that are important and not covered in another environmental indicator.

  • Risk Management Plan (RMP) sites are included because of the potential severe effects of an accidental release of a highly hazardous substance into the air.
  • Treatment Storage and Disposal Facilities are included because they were the focus of much early EJ research and community action.
  • EPA National Priorities List (NPL)/ Superfund sites are included because of the concerns associated with being in close proximity to an NPL site.

Top of Page


Why aren't Toxic Release Inventory (TRI) sites included?

Around 60% of TRI facilities emit hazardous air pollutants and would therefore, in most cases, be included in EJSCREEN’s National-Scale Air Toxics Assessment (NATA) environmental indicators. In addition, there is some further overlap between TRI and RMP facilities.

Top of Page


How does EJSCREEN measure “low-income” and “minority”?

Low-income is defined the number or percent of a block group’s population in households where the household income is less than or equal to twice the federal poverty level. Minority is defined as all but Non-Hispanic White Alone.

Top of Page


Why are NATA results and other air quality data (e.g., for ozone and PM) in EJSCREEN presented at the census tract level and not at a more refined scale?

NATA (National Air Toxics Assessment) modeling results illustrate geographic patterns of exposure and potential health risk from air toxics. These results can then inform efforts to prioritize pollutants and geographic areas of interest or to suggest more refined data collection such as monitoring. Ozone and PM air quality concentrations are derived from both ambient monitoring data and from regional-scale modeling.

Risk information and PM and ozone concentrations are presented at the census tract level rather than the county level so that patterns of relatively lower and higher levels of risk and concentration data within a county can be seen, rather than one result for an entire county. The predicted risks and air quality concentrations are not suited to pinpointing either specific concentration levels or exact locations where higher risks or concentrations may exist but rather to illustrate broader-scale geographic patterns of air quality. The census block results presented by EJSCREEN site are actually census tract values distributed homogeneously across all census blocks within a census tract.

Top of Page


Why are cancer risks from diesel PM not included in EJ Screen results?

The Diesel PM indicator in EJSCREEN measures concentrations, not cancer risk. Cancer risks from diesel PM are not in EJSCREEN because EPA has not developed a carcinogenic potency for this pollutant. EPA will continue to evaluate the feasibility of quantifying cancer risks from diesel exhaust. However, EPA has concluded that diesel exhaust is among the substances that may pose the greatest risk to the US population.

Top of Page


Can I add my own data into EJSCREEN? Can I add my own boundaries / locations?

Any layer that is available through an online service (i.e. EPA’s GeoPlatform or ArcGIS) can be added. EJSCREEN will only display the added layer; it will not integrate the added information into the calculation of the EJ indexes. For example, if you add a data layer that maps impaired water bodies, EJSCREEN will show this layer in addition to other EJSCREEN data. However, it will not provide quantitative information about the layer you added.

Top of Page


What other limitations does EJSCREEN have?

EJSCREEN is a screening tool for pre-decision use only. It can help identify areas that may warrant additional consideration, analysis, or outreach. This screening tool does not provide data on every environmental impact and demographic indicator that may be relevant to a particular location. EJSCREEN outputs should be supplemented with additional information and local knowledge before taking action to address potential EJ concerns Important caveats and uncertainties apply to this screening-level information, so it is essential to understand the limitations on appropriate interpretations and applications of these factors. Please see EJSCREEN documentation for discussion of these issues before using reports.

Top of Page


What additional supplementary data is available in EJSCREEN outside of the 11 environmental variables?

Outside of the eleven environmental indicators, EJSCREEN provides additional environmental data layers, layers for delineating boundaries, and other data on locations of EPA grant recipients. The tool also provides printed reports from selected areas with a wide variety of data from the decennial Census and American Communities Survey.

Top of Page


How do I cite EJSCREEN?

If you use information from EJSCREEN, please cite the information as follows:

United States Environmental Protection Agency. 2017. EJSCREEN. Retrieved: Enter Month, Day, Year, from url (the url cited should be the exact url you accessed) or www.epa.gov/ejscreen for a general citation. To cite specific data content, please use the citation contained within the relevant metadata.

To cite specific EJSCREEN publications (e.g., journal articles), please use the appropriate citation. For the EJSCREEN Technical Documentation, please cite as follows (using the relevant year to specify which version of documentation is being cited):

U.S. Environmental Protection Agency (EPA), 2017. EJSCREEN Technical Documentation.

Top of Page


Are people living in areas with a high lead indicator, indicating a higher percentage of pre–1960s housing than other block groups, always at high risk of lead hazards?

No. The lead paint indicator is based solely on the age of the housing stock in a selected block group and highlights homes built prior to 1960 because lead paint was commonplace during that era. The indicator does not, however, take into account any remediation of lead paint which has occurred through government programs to reduce lead in homes, general home renovations or other factors. For this reason, many areas that include government-assisted housing rank high in the EJSCREEN lead paint indicator when in fact, housing that is government-assisted is, on average, significantly more lead safe than unassisted housing from that era.

Similarly historic neighborhoods often appear in the top percentile of the lead paint indicator despite the fact that these historic homes may be lead safe as a result of remediation. This example highlights how EJSCREEN should be used for screening purposes only and why it is critical to obtain additional information before identifying a concern.

Top of Page


Why do some locations have different environmental/demographic, EJ indexes, and other mapping results at different points in time?

EJSCREEN results are not static because the primary environmental and demographic indicators, which underpin the tool, are regularly updated. The demographic data is updated annually to reflect the most recent Census datasets. The primary environmental datasets are also updated annually, if new data is available. In addition, EJSCREEN uses map services for many of the “additional maps” available in the tool. A map service links to an outside organization’s maps, so as that organization updates its maps, the changes will automatically be reflected in EJSCREEN. Finally, one other potential reason for variation in EJSCREEN results over time is changes to the underlying calculations. EPA is constantly trying to find the best way to represent EJSCREEN data. This may result in occasional tweaks to the formulas and code behind the tool during the update process, which in turn can change how an area is displayed. For more information on the calculations, please see the EJSCREEN Technical Documentation.

Top of Page


How does the wastewater discharge indicator work and why does my location report high?

To understand why a given location’s wastewater discharge indicator is high, it is necessary to understand how the indicator functions. The wastewater discharge indicator takes the pollutant discharge information reported from facilities to EPA and assigns it to the streams and rivers which receive those discharges. This complex mapping process includes toxicity-weighted results, or giving more weight to the pollutants which have greater impact on human health. It also must account for dilution as these pollutants move downstream. Following this, the indicator ranks Census block groups based on the proximity to these stream segments and the toxicity-weighted pollutant discharge.

Because EJSCREEN is a screening tool, the wastewater discharge indicator should be validated with other information, including local and state data. One source of data which may be helpful as a first step is looking at the reported pollutant data underlying this indicator. This data is public and can be found in the EPA’s DMR Pollutant Loading Tool at https://cfpub.epa.gov/dmr/. A more detailed explanation of the wastewater discharge indicator can be found in the EJSCREEN Technical Documentation.

Top of Page


Why do some locations have high percentile scores when the raw data seem to be low?

High percentile scores occasionally can exist in areas with low raw data scores for a number of reasons. It usually occurs when there are very few facilities or potentially polluted block groups in the entire comparison area, such as within the entire state, or when the distribution of the affected block groups across the landscape is uneven. EJSCREEN ranks each block group and then places the block groups into percentile bins ranging from 0 – 100. If a large number of block groups are tied at a low or zero raw data score, then they may appear as high percentile scores because EJSCREEN rounds the tied scores to the upper end. For example, if 92% of all block groups have a zero value for a given indicator, all the block groups would score as 0 – 92 and would round up to the 92nd percentile. In addition, zero or low raw data scores can receive the highest percentile when there are few block groups with high scores.

These issues occurred more commonly in older versions of EJSCREEN with indicators that had a small number of affected areas, such as the hazardous waste proximity, superfund proximity and lead paint indicators. Changes to the proximity calculations and the way EJSCREEN represents zero have remedied most of these issues. However, EPA will continue to review and look for better ways to display this complex data in a user-friendly manner.

Top of Page