EJSCREEN: Environmental Justice Screening and Mapping Tool

Frequent Questions about 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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.

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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.
  • Major direct water dischargers are included because they are the largest point sources that discharge directly to water bodies.

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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.

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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.

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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.

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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.

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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.

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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.

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

Outside of the twelve 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 2010 and 2000 Census and 2012 American Communities Survey.

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How do I cite EJSCREEN?

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

United States Environmental Protection Agency. 2015. 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), 2015. EJSCREEN Technical Documentation.

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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.

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Why do some locations appear to have high environmental indicators or EJ indexes, especially compared to the state, when there are no facilities in the area?

Because EJSCREEN uses percentiles to compare locations, states with no or a very small number of a given type of facility can have extremely high percentiles in certain environmental indicators and their corresponding EJ indexes. This is due to the way EJSCREEN represents ties which is to report the high end of the range. For example, if an entire state only has a couple of hazardous waste facilities then only the block groups within 50 kilometers of that location will receive proximity scores. Therefore all the other block groups in the state would have proximity scores set at zero and be tied at a percentile such as the 0–97th percentile. As a result, EJSCREEN would report those block groups at the 97th percentile and most of the state would appear in the 95–100th percentile, or red on the map, despite the absence of hazardous waste facilities within 50 kilometers of these block groups. EPA is currently reviewing the underlying calculations, how best to communicate these results, and if it is necessary to make changes to this in future iterations of the tool. This happens most commonly in indicators that have a small number of affected areas such as hazardous waste proximity, superfund proximity and the lead paint indicators. It can also happen with the linguistically isolated demographic indicator.

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