Air Monitoring Station HAPs Report Help

The Air Monitoring Station (AMS) Report provides detailed information about ambient air quality, weather station information, and facility emissions near an ambient air monitoring station for Hazardous Air Pollutants (HAPs).

The Air Monitoring Station Report is an interactive report that allows you to quickly find data of interest. Data are organized into five primary categories, each of which is controlled by expandable/collapsible sections that allow you isolate the information that is of most interest.

 Monitor Summary

View the ambient air monitoring stations and surrounding facilities reporting air emissions or having ICIS-Air IDs.  Using the + / - controls on the map or your wheel on your mouse, pan or zoom into the map to an area of interest. To reset the map to its original location and extent, click the "Map Reset" button. You can also use the "Expand Map" feature to expand the map to the full width of the page. Users have the option to show/hide facilities within 5 km of the air monitoring station:

  • Show Air Facilities - displays facilities with an ICIS-Air ID or reported hazardous air pollutant (HAP) air emissions.
  • Show Air Facilities with HAP Emissions - displays facilities with reported HAP in TRI or NEI. If a pollutant is selected from the Pollutants Monitored table, this will show facilities with reported emissions of the selected pollutant.
  • Show All Facilities - displays all regulated facilities in ECHO (e.g., any facility with an FRS ID).

 Map Legend

Air monitoring station Represents an ambient air monitoring station.

Stripe color corresponds to the statute under which the facility is regulated.
Multimedia marker Multimedia (multiple statutes)
RCRA marker Resource Conservation and Recovery Act (RCRA)
CWA marker Clean Water Act (CWA)
SDWA marker Safe Drinking Water Act (SDWA)
CAA marker Clean Air Act (CAA)
CAA marker None of the above (Facility Registry Service (FRS)-only facility)

Body color corresponds to compliance status of the facility.
Serious noncompliance marker Facility is in serious noncompliance
Compliance marker Facility has no violations in database
Noncompliance marker Facility is in noncompliance
Compliance information unavailable marker Facility whose compliance information is unavailable, or which is unregulated or unpermitted

Icon numbering corresponds to the number of years since the facility was last inspected.
1 years since inspection marker2 years since inspection marker3 years since inspection marker4 years since inspection marker5 years since inspection marker
Longer than 5 years since inspection marker Longer than 5 years
Never inspected marker Never inspected

Icon size differentiates between major and minor facilities.
Minor facility marker Minor facility
Major facility marker Major facility

Cluster of multiple facilities marker Represents a cluster of multiple facilities located in a specific region
Facilities with estimated latitude/longitude markerRepresents a facility with approximated latitude/longitude coordinates

Monitor Information

AMA Site Code

The Ambient Monitoring Archive (AMA) Site Code uniquely identifies an Ambient Monitoring Station (AMS).


State where the station is located.

Monitor Latitude/Longitude

Displays the latitude and longitude of the station.

Location Type

Displays the location type of the AMS. Definitions of location types are consistent with the definition EPA used to support the Integrated Urban Air Toxics Strategy:

  • Rural - A county is considered “rural” if it does not contain a metropolitan statistical area with a population greater than 250,000 and the U.S. Census Bureau does not designate more than 50 percent of the population as “urban.” Note that this definition does not necessarily apply for any regulatory or implementation purpose.
  • Micropolitan Statistical Area - An area that contains an urban core of at least 10,000 (but less than 50,000). Each micropolitan area consists of one or more counties and includes the counties containing the core urban area, as well as any adjacent counties that have a high degree of social and economic integration with the urban core. Note that this definition does not necessarily apply for any regulatory or implementation purpose.
  • Metropolitan Statistical Area - An area that contains a core urban area of 50,000 or more population. Each metropolitan area consists of one or more counties and includes the counties containing the core urban area, as well as any adjacent counties that have a high degree of social and economic integration with the urban core. Note that this definition does not necessarily apply for any regulatory or implementation purpose.

For more information, visit the Office of Management and Budget's page on Metropolitan and Micropolitan Statistical Areas.


Identifies the monitoring program(s) for the air monitoring station.

Weather Station Information

Nearest Weather Station

The name and 5-digit code of the Weather-Bureau-Army-Navy (WBAN) station located closest to the air monitoring station.

Station Location

The location (e.g., city, state) of the weather station.


Displays the latitude and longitude of the weather station.

Pollutants Monitored

This table displays a concentration trend sparkline and cancer risk of the monitored air pollutants at the station. Hovering over points in the sparkline will display information on the year,  average daily concentration, and the number of days that pollutant concentration measurements were taken within the year (daily measurements). Select a pollutant from the table to display more detailed information in the Ambient Conditions and Annual Statistics sections of the Air Monitoring Station Report.

Maximum Cancer Risk from Monitor Measurements: By default, the highest annual cancer risk in the last 5 or 10 years of air quality data. Cancer risk is calculated using the unit risk estimate (URE) for inhalation. The URE represents the upper-bound excess lifetime cancer risk estimated to result from continuous pollutant exposure over a lifetime at a concentration of 1 µg/m3 in air. The URE is multiplied by the measured ambient annual pollutant concentration to estimate the cancer risk for each pollutant detected by the ambient monitor. The cancer risk represents the number of people out of one million who would contract cancer if continuously exposed over 70 years (an assumed lifetime). For more information about the URE for inhalation, see carcinogenic risk assessment.

Choose a Timeframe for Cancer Risk: Select a timeframe for the annual cancer risk values displayed in the Pollutants Monitored table.  When "last 5 years" or "last 10 years" is the selected timeframe, the report shows the highest annual cancer risk value of the years within that timeframe. The dropdown selections are limited to the years where data are available.

 Ambient Conditions

Pollution Rose

Graphically displays the average daily concentration vs. the average daily wind direction at the ambient monitoring station during the selected timeframe. ECHO uses National Weather Service (NWS) data correlate wind direction and speed with measured hazardous air pollutant (HAP) concentrations from the AMA. 

Each point represents one reading from the monitoring station for the selected pollutant. Its direction in relation to the center of the rose represents the cardinal direction of the wind on the day of the reading, and its distance from the center represents the magnitude of the reading. Concentrations are shown in μg/m3. Hover over a point on the graph to view the concentration value and measurement date.

Wind Rose

Graphically displays the relative frequency of hourly wind speed and direction at the nearest weather station during the selected timeframe. Wind direction and speed data are from the National Weather Service.

 Annual Statistics

Displays a summary of annual average concentrations by year for the pollutant selected from the Pollutants Monitored table. ECHO includes AMA data and displays HAP concentrations as annual averages. See About the Data for the available years of data. 

Download Pollutant Monitoring Data allows users to download a CSV file of the raw AMA ambient monitoring data for the selected station and pollutant, from which the annual statistics shown on the Air Monitoring Station Report were calculated. Documentation for the AMA data, including a data dictionary, is provided on EPA's Air Toxics Data webpage (see documentation below the state data table). 

Select View Trends Plot to show the concentrations trends visually. The Trends Plots are developed by EPA OAQPS. Note that trends plots may not be available for every monitoring station and pollutant.


Year of the annual summary.

Monitoring Program

Identifies the monitoring program for the ambient monitoring station. 

Number of Daily Measurements Per Year

The number of days in a given year that pollutant measurements were taken. 

Average Concentration (ug/m3)

Central tendency of the observed daily measurements.

Maximum Concentration (ug/m3)

Maximum value of observed daily concentrations.

Median Concentration (ug/m3)

50th percentile of observed daily concentrations.

Variance (ug/m3)

Describes the variability of the observed daily concentrations.

Reference Concentration (ug/m3)

Concentration value at which adverse health effects may occur from long-term exposure. The AirToxScreen reference concentration is an estimate (with uncertainty spanning perhaps an order of magnitude) of a continuous inhalation exposure to the human population (including sensitive subgroups that include children, asthmatics, and the elderly) that is likely to be without an appreciable risk of deleterious effects during a lifetime. Refer to the 2017 AirToxScreen Technical Support Document for more information.

2017 AirToxScreen Modeled Concentration (mg/m3)

Predicted concentration from 2017 AirToxScreen based on emissions, meteorology, geography, and demographics.

Percent of Daily Measurements over 2017 AirToxScreen Modeled Concentration

Percentage of observed average daily concentrations at the station that were greater than the 2017 AirToxScreen modeled concentration.

 Facility Emissions

This section of the report displays facilities with ICIS-Air IDs or reported air emissions located within 5 km of the air monitoring station. Selecting a pollutant from the Pollutants Monitored table filters the list of facilities to those with emissions corresponding to the selected pollutant. Click on a row in the facility emissions table to zoom to the selected facility's location on the map.

Facility Name

Company or permit holder name, as maintained in FRS. Note that the facility name may differ across EPA databases due to differences in reported information, change in ownership, use of parent or subsidiary name, etc. 


Additional ECHO reports that are available and accessible by clicking on the corresponding icons. The Reports Legend provides descriptions of each report icon.

TRI Emissions (lb/year)

Toxics Release Inventory (TRI) chemical releases represent the chemical releases to air, in pounds, as reported to TRI by the facility for the most recent reporting year. Total hazardous air pollutants (HAPs) are displayed by default. 

NEI Emissions (lb/year)

The amount of air pollutants released to air in tons per year, as reported in the most recent National Emissions Inventory (NEI). Total hazardous air pollutants (HAPs) are displayed by default.


Environmental Justice

This section provides information about the Environmental Justice (EJ) and Supplemental Indexes of EJScreen, EPA's screening tool for EJ concerns, for the area the station is located. EPA uses these indexes to identify geographic areas that may warrant further consideration or analysis for potential EJ concerns. Note that use of these indexes does not designate an area as an "EJ community." EJScreen provides screening level indicators, not a determination of the existence or absence of EJ concerns. For more information, see the EJScreen homepage or the DRF Data Dictionary.

Selections and Data Table

The default selection is national Supplemental indexes. You can select to view state percentiles, as well as switch between index types using the radio buttons. The data table shows the selected index percentiles calculated two ways: for the census block group the station is located in, and for the maximum percentile for EJ indexes across all census block groups within a 1-mile radius of the station. The indexes for the 1-mile maximum are derived in ECHO by selecting the highest percentile of an index across all census block groups intersecting within the 1-mile radius around the station. Percentiles with values 80 or above are flagged with a red icon.

Interactive Map

The interactive map centers on the station location (map pin), as well as the census block group the station is located in (outlined in teal). A 1-mile radius around the station is also drawn so users can view all the census block groups that intersect this area. Census block groups are shaded based on the counts of indexes at or above the 80th percentile for the selected index type. Select within the area of any census block group to view a popup with environmental justice and socioeconomic information related to this area.

Related Reports

Provides a link to an EJScreen Report  for the area surrounding the station's location (based on latitude and longitude). This EPA report provided through the EJScreen website displays additional information to what is shown in ECHO and includes a method for combining environmental and demographic indicators into EJ indexes.

Demographic Profile of Surrounding Area

This section provides demographic information regarding the community surrounding the monitor. Statistics are based upon the 2010 U.S. Census and 2016 - 2020 American Community Survey (ACS) 5-year Summary and are accurate to the extent that the monitor latitude and longitude listed below are correct. EPA’s spatial processing methodology considers the overlap between the selected radii and the census blocks (for U.S. Census demographics) and census block groups (for ACS demographics) in determining the demographics surrounding the monitor. For more detail about this methodology, see the DFR Data Dictionary.

Select Radius

Choose a 1-mile, 3-mile, or 5-mile radius surrounding the air monitoring station to show demographic information for that area.