Air Monitoring Station CAPs 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. 

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 to isolate the information that is of most interest. 

 Monitor Summary

View the locations of ambient air monitoring stations monitoring for criteria air pollutants and surrounding facilities on the map.

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 a 5 km radius of the air monitoring station:

  • Show Air Facilities - displays facilities with an ICIS-Air ID or facilities reporting emissions of criteria air pollutants.
  • Show Facilities with CAP Emissions - displays facilities with reported CAP emissions 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

AQS Site Code

The AQS Site Code is a 9-digit unique identifier for the air monitoring station, created based on the combination of the 2-digit State code + 3-digit County code + 4-digit Site Code.


The state where the air monitoring station is located.

Monitor Latitude/Longitude

Displays the latitude and longitude of the station is located.

Location Type

Displays the location type of the AMS.

  • Rural
  • Urban
  • Suburban

The source of this information is the Site Listing CSV file on EPA's AQS website. For more information, visit the AirData Download Files Documentation.


A list of the monitoring networks (i.e., groups of monitors with common goals and procedures) to which the station belongs.

Weather Station Information

Nearest Weather Station

Meteorological data is sourced from the Iowa Environmental Mesonet (IEM) data and Air Quality System (AQS). Weather station names from IEM have a 3-characheter meteorological code, while weather station names from AQS have a 9-character meteorological code.

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 information by pollutant. Each pollutant is further separated by its pollutant standard and displays a concentration trend sparkline as well as the count of primary and secondary NAAQS exceedances.

Hovering over points in the sparkline will display information on the year, average daily concentration, and the number of days that pollutants 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.

Count of Primary NAAQS Exceedances

The number of measurements that exceeded the NAAQS primary standard for that pollutant for the timeframe selected.

Count of Secondary NAAQS Exceedances

The number of measurements, if applicable, that exceeded the NAAQS secondary standard for that pollutant for the timeframe selected.

Choose a Timeframe for NAAQS Exceedances

Select a timeframe for the annual NAAQS Exceedance values displayed in the Pollutants Monitored table. The most recent year is selected by default. The dropdown values are limited to the years where monitoring data is available.

Clear Pollutant Selection

Allows users to reset the Air Monitoring Report by clearing information about any pollutants that were selected.

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 Ambient Conditions

Choose a Timeframe

Select a timeframe for the annual concentration measurements displayed in the Time Series Chart and the annual Wind Rose. The year selected in the "Monitor Summary" section is selected by default. The dropdown selections are limited to the years where the data is available.

Time Series Chart

Graphically displays the daily pollutant concentration for the year. By default, the pollutant standard that is chosen from the "Pollutants Monitored" table is displayed on the map, as well as the Primary NAAQ Standard. User can select to compare the measured values on the Time Series Chart to either the Primary or Secondary NAAQ Standard.

Wind Rose

Graphically displays the relative frequency of hourly wind speed and direction at the nearest weather station during the selected timeframe. Users can zoom into a specific timeframe within Time Series Chart to see the Wind Chart specific for that timeframe. Wind direction and speed data are from either the Iowa Environmental Mesonet (IEM) Exit data or Air Quality System (AQS).

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 Annual Statistics

Displays a summary of annual average concentrations by year for the pollutant selected from the Pollutants Monitored table. The table displays pollutants concentrations from AQS as annual averages. See About the Data for the available years of data.

Download Sample Measurement Data allows users to download a CSV file of the AQS monitoring concentration data for the selected station and pollutant, from which the annual statistics were calculated.

Documentation for the AQS data, including a data dictionary, is provided on EPA's Air Quality System webpage (see documentation in the "About the Data" Section).


Calendar year that the station monitored for the selected pollutant.

Monitoring Network

Identifies the monitoring network for the air monitoring stations.

Pollutant Standard

The pollutant standard by which the measurement was taken.

Sample Frequency

The sampling frequency of the pollutant. Sample frequencies for each pollutant type are listed in EPA's NAAQS Table.

Number of Measurements Per Year

The number of measurements taken for during the given year.

Average Concentration

Central tendency of the observed daily measurements.

Maximum Concentration

Maximum value of observed daily concentrations.

Units of Measurement

The units of measurement for the concentration. The NAAQS Table lists the units of measurement for each pollutant.

Standard Deviation

Describes the variability of the observed daily concentrations.

Count of Primary Exceedances

The count of measurements that exceeded the primary standard in the given year.

Count of Secondary Exceedances

The count of measurements that exceeded the secondary standard in the given year.

Percent of Measurements Exceeding Primary Standard

The percent of measurements that exceeded the primary standard in the given year.

Percent of Measurements Exceeding Secondary Standard

The percent of measurements that exceeded the secondary standard in the given year.

Percent of Measurements Below MDL

The percent of measurements that fall below the minimum detection level (MDL). The MDL is the minimum concentration that can be measured with 99% confidence that the value is above zero. 

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 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 this 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 facility-level reports in ECHO that are accessible by selecting the corresponding icon. The Reports Legend provides descriptions of each report icon.


The name of the pollutant corresponding to the selected value in the Pollutants Monitored table. If a pollutant is not selected, this will display "Total CAPs".

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 criteria air pollutants (CAPs) 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 criteria air pollutants (CAPs) are displayed by default.

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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 DFR 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.