Air Monitoring Station Search Results Help - HAPs

On This Page:

• Interact With the Map
• Current Search
• Filter Monitors
• Pollutants Monitored
• Customize Map Layers
• Results Guide

Interact with the Map

ECHO displays air monitoring stations included in your search results on an interactive map. Only those stations with available geographical data are mapped. An icon is included in the data table to indicate whether a station is mapped. You may use the +/- controls on the map or the wheel on your mouse to pan or zoom into the map.

Select a data table row or a map icon to zoom and reposition the map to the selected station's location. The selected station will appear in the Pollutants Monitored section, to the right on the map, and a map pop-up will display the following monitoring station information:

• View Monitoring Station Data
• AMA Site Code
• State
• Location Type
• Nearest Weather Station
• Average Cancer Risk from Monitor Measurements
• Median Cancer Risk from Monitor Measurements
• Maximum Cancer Risk from Monitor Measurements
• Recent Cancer Risk from Monitor Measurements

You can control how your map looks by adjusting the base layer. "Imagery with Labels" is selected by default. Select Basemap Options to change your view to one of the following choices:

• Imagery
• Imagery with Labels
• Streets
• Topographic
• Oceans
• Oceans with Labels
• Dark Gray Canvas
• Dark Gray Canvas with Labels
• Light Gray Canvas
• Light Gray Canvas with Labels
• National Geographic
• Terrain
• Terrain with Labels
• Shaded Relief
• Shaded Relief with Labels
• USA Topo Maps

The Map Legend describes the symbols used on the map. Select the Map Legend button in the top left of the map to expand the legend. The symbols used are described in detail below:

Current Search

The number of monitors returned in your search is displayed in this panel. ECATT also keeps track of your selected search criteria.

Additional criteria can be added or changed directly on the results page using the interactive features under Explore Air Monitoring Criteria.

Explore Air Monitoring Criteria

Choose a Timeframe

Search for stations by the year of ambient pollutant measurements, up to the last ten reporting years. Adjust the timeframe to either the Last 10 years, Last 5 years, or any calendar year since 2008. “Last 10 years” is selected by default.

Set Non-Detects Equal To

When a pollutant concentration is reported as "not detected," its actual concentration may be zero or some value between zero and the detection limit. The user can choose to calculate the average pollutant concentration using one of three methods: setting all non-detects to zero, setting all non-detects to ½ the detection limit, or using the regression method. By default, non-detects are set to use regression method, and "Exclude Results with More than 80% Non-Detects" is selected.

Aggregate or Single Pollutant

Update the search to identify stations monitoring a particular pollutant. For a particular pollutant(s), select "Single Pollutant" and then select a pollutant name from the second dropdown list.

Once a single pollutant is selected, the page will reload and the following additional choices will become available in the Filter Monitors panel, Metric dropdown: "Average Concentration," "Median Concentration," and "Maximum Concentration." Selecting any of these three options will change the Ambient Concentration slider according to the specific calculation. It will also change the Modeled Risk Screening section from AirToxScreen Long-Term Cancer Risk (people in a million) to AirToxScreen Concentration (ug/m3) and the slider percentiles will update based on the data to match the chosen selection. 

Enter AMA Site Codes

Further refine your results by specifying unique AMA site codes. You can search for multiple IDs by using a comma-separated list.

You can further tailor your search using additional search terms on the search form. Select "Modify Search" to take you to the Search page with your previous search criteria retained.

Filter Monitors

Several interactive filters are provided, grouped using the same organizing principles used on the search form. Filters allow you to add an additional layer of analysis within your current search without affecting the universe of results. The counts displayed in the Current Search panel will remain frozen as you manipulate different filters to further analyze the data.

Mapping Mode

Users can select statistical average metrics from the dropdown menu, along with the corresponding Target System for Hazard Index. For Single Pollutant filtering, the Hazard Quotient option becomes available under the Mapping Mode metric dropdown. 

Geographic Characteristics

Users can filter on Location type by Metropolitan, Micropolitan, or Rural areas. Stations Located On or Near Tribal Land can be filtered with the corresponding slider from zero to 25+ miles.

Ambient Air Quality Characteristics

Stations with an Aggregate Hazard Index can be selected using the checkbox and corresponding slider for Measured Respiratory Hazard Level of zero to 20. Users can also select the checkboxes to compare Ambient Daily Average Measurements to Modeled Concentrations, from 2x-10,000x. For Single Pollutant filtering, Air Concentration Trend appears in this section with options for increasing and decreasing. The Median Long-Term Cancer Risk (people in a million) slider can be used to filter from zero-100, and Compare Ambient Daily Average Measurement to Modeled Concentrations allows the user to choose concentrations of 2x-10,000x. The Number of Monitors with selected Target System Hazard Level slider is also available from zero-20 with Single Pollutant filtering.

Modeled Risk Screening

This checkbox is used for selecting Monitors that include the previously selected Mapping Mode metric (Avg Cancer Risk, Median Cancer Risk, Maximum Cancer Risk, Most Recent Avg Cancer Risk, or Hazard Index.) The slider allows you to choose the corresponding risk or index level from the selected Mapping Mode criteria.

Pollutants Monitored

Upon selecting a table row (or on a map pin), the Pollutants Monitored panel will expand (or update) to present a table displaying the annual concentration trend sparkline of the air pollutants monitored at the selected station. Hovering over points in the sparkline will display information on the year, average daily concentration, and the number of daily pollutant measurements for the given year.

In addition, you may access the Air Monitoring Station Report for the selected station by selecting the hyperlinked AMA Site Code displayed above the table. The Air Monitoring Station Report provides detailed information about ambient air quality, weather station information, and facility emissions near an ambient air monitoring station.

Customize Map Layers

ECHO provides additional analytical capabilities by allowing you to select map layers to enhance your analysis. ECHO leverages map services available from other programs and sources. Each map layer requires a specific map scale for display. Layers are only available for selection if the map is zoomed in to a sufficient scale which is indicated next to the layer name (e.g., 48%). To assist you in determining how much farther you may need to scale the map, the current zoom level is displayed. Note: ECHO will display a warning indicator if a previously selected layer is disabled due to the current map scale, alerting you to zoom farther in to re-enable the layer. Click Clear Layers to remove all layers from the current map view.

ECHO provides access to the following map layers. Click the Info icon displayed next to each layer in the Layers panel to view a description of each layer and display the layer legend.

• EJScreen Maps (Only one layer may be enabled at a time)
  • Summary Maps
    • Number of Supplemental Indexes at or above  80th Percentile (U.S.)
    • Number of Supplemental Indexes at or above  80th Percentile (State)
    • Number of EJ Indexes at or above 80th percentile (U.S.)
    • Number of EJ Indexes at or above 80th percentile (State)
• Supplemental Indexes (US - Block Group)
  • Particulate Matter 2.5
  • Ozone
  • Diesel Particulate Matter
  • Air Toxics Cancer Risk
  • Air Toxics Respiratory Hazard Index 
  • Toxic Releases to Air
  • Traffic Proximity
  • Lead Paint
  • Superfund Proximity
  • RMP Facility Proximity
  • Hazardous Waste Proximity
  • Underground Storage Tanks (UST)
  • Wastewater Discharge 
• EJ Indexes (US - Block Group)
  • Particulate Matter 2.5
  • Ozone
  • Diesel Particulate Matter
  • Air Toxics Cancer Risk
  • Air Toxics Respiratory Hazard Index 
  • Toxic Releases to Air
  • Traffic Proximity
  • Lead Paint 
  • Superfund Proximity 
  • RMP Facility Proximity
  • Hazardous Waste Proximity
  • Superfund Proximity
  • Underground Storage Tanks (UST)
  • Wastewater Discharge 
• Socioeconomic Indicators
  • Demographic Index
  • Supplemental Demographic Index
  • People of Color Population
  • Low Income (<2x poverty level)
  • Unemployment Rate
  • Limited English speaking
  • Less than HS Education
  • Under Age 5
  • Over Age 64
• Environmental Indicators 
  • Particulate Matter 2.5
  • Ozone
  • Diesel Particulate Matter
  • Air Toxics Cancer Risk
  • Air Toxics Respiratory Hazard Index 
  • Toxic Releases to Air
  • Traffic Proximity
  • Lead Paint 
  • Superfund Proximity
  • RMP Facility Proximity
  • Hazardous Waste Proximity
  • Underground Storage Tanks (UST)
  • Wastewater Discharge 
• Climate Change Data
  • Flood Risk
  • Fire Risk
  • 100 Year Floodplain (FEMA)
  • Sea Level Rise (NOAA)
    • 1ft Sea Level Rise
    • 2ft Sea Level Rise
    • 3ft Sea Level Rise
    • 4ft Sea Level Rise
    • 5ft Sea Level Rise
    • 6ft Sea Level Rise
• Air Maps
  • Nonattainment Areas by Pollutant
    • Ozone 8-hr (2008 standard)
    • Ozone 8-hr (2015 standard)
    • Lead (2008 standard)
    • SO2 1-hr (2010 standard)
    • PM 2.5 24hr (2006 standard)
    • PM 2.5 Annual (1997 standard)
    • PM 2.5 Annual (2012 standard)
    • PM10 (1987 standard)
    • CO (1971 standard)
    • NO2 (1971 standard)
  • Total Cancer Risk (per million)
  • Whole Body Hazard Index
• Places
  • Schools K-12 Public and Private
  • Colleges/Universities
  • Hospitals
• Boundaries
  • Indian Country Boundaries
  • Federal Legislative Districts
  • Superfund Site Boundaries

Results Guide

Tip: Sort tabular data by clicking on the column heading.

You can further manipulate the data presented using either the Customize Columns or Download Data buttons.

Select the Customize Columns button to customize the tabular data to focus on the data most important to you. Data fields available for selection include (select on the links below to jump to detailed descriptions of each):

Use the "Select All" link to quickly include all columns for display or use the "Clear All" link to clear all selections. Note: AMA Site Code is always included and cannot be unchecked.

ECHO allows you to download your search results for further analysis. Click Download Data to download tabular data in comma-separated value (CSV), Excel (XLS), or GEOJSON formats.

The search results present data from several EPA data sources. Read About the Data for more information on each data source and when the data were last updated in ECHO.

Data fields included in the search results are described below. 

Site Information

AMA Site Code

Ambient Monitoring Archive Site Code identifies a unique Ambient Monitoring Station (AMS).

Location

Describes the county and state of the AMS.

Map

Graphical indicator denoting whether geographical data required to map an AMS are available.

Street Address (Address, City, County, Location, State, and ZIP Code)

Street address, city, state, and ZIP code where AMS is located, as maintained by each data system.

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. Note that the definitions do not necessarily apply for any regulatory or implementation purpose.

• 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.”
• 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.
• 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.

Program

The regulatory air program(s) that a particular air monitoring station participates.

FIPS Code

The Federal Information Processing Standards (FIPS) code to identify the county that the AMS is located in.

EPA Region

The EPA region where the AMS is located. EPA has 10 regional offices that execute programs within several states and territories.

Regional Planning Organization (RPO)

Displays which of one of the five EPA funded RPOs the AMS is located in:

• Western Regional Air Partnership (WRAP)
• Central Regional Air Planning Association (CENRAP)
• Midwest Regional Planning Organization (Midwest RPO)
• Mid-Atlantic/Northeast Visibility Union (MANE - VU), and
• Visibility Improvement State and Tribal Association of the Southeast (VISTAS).

Latitude/Longitude

Displays the latitude and longitude of the air monitoring station.

Hazard Quotient

The ratio of the potential exposure to a substance and the level at which no adverse effects are expected (calculated as the exposure divided by the appropriate chronic or acute value). A hazard quotient of 1 or lower means adverse noncancer effects are unlikely, and thus can be considered to have negligible hazard. More information on hazard quotients can be found in Section 6 of the AirToxScreen Technical Support Document.

Measured Hazard Levels - Single Pollutant Search

• Measured Respiratory Hazard Quotient
• Measured Liver Hazard Quotient
• Measured Developmental Hazard Quotient
• Measured Reproductive Hazard Quotient
• Measured Kidney Hazard Quotient
• Measured Ocular Hazard Quotient
• Measured Endocrine Hazard Quotient
• Measured Hematological Hazard Quotient
• Measured Immunological Hazard Quotient
• Measured Skeletal Hazard Quotient
• Measured Spleen Hazard Quotient
• Measured Thyroid Hazard Quotient
• Measured Wholebody Hazard Quotient

Modeled Hazard Levels - Single Pollutant Search

• AirToxScreen Respiratory Hazard Quotient
• AirToxScreen Liver Hazard Quotient
• AirToxScreen Developmental Hazard Quotient
• AirToxScreen Reproductive Hazard Quotient
• AirToxScreen Kidney Hazard Quotient
• AirToxScreen Ocular Hazard Quotient
• AirToxScreen Endocrine Hazard Quotient
• AirToxScreen Hematological Hazard Quotient
• AirToxScreen Immunological Hazard Quotient
• AirToxScreen Skeletal Hazard Quotient
• AirToxScreen Spleen Hazard Quotient
• AirToxScreen Thyroid Hazard Quotient
• AirToxScreen Wholebody Hazard Quotient

Hazard Indices

The sum of hazard quotients for substances that affect the same target organ or organ system. The Hazard Index (HI) is only an approximation of the aggregate effect on the target organ (e.g., the lungs) because some of the substances might cause irritation by different (i.e., non-additive) mechanisms. As with the hazard quotient, aggregate exposures below an HI of 1.0 derived using target organ specific hazard quotients likely will not result in adverse non-cancer health effects over a lifetime of exposure and would ordinarily be considered acceptable. An HI equal to or greater than 1.0, however, does not necessarily suggest a likelihood of adverse effects. Because of the inherent conservatism of the reference concentration (RfC) methodology, the acceptability of exceedances must be evaluated on a case-by-case basis, considering such factors as the confidence level of the assessment, the size of the uncertainty factors used, the slope of the dose-response curve, the magnitude of the exceedance, and the number or types of people exposed at various levels above the RfC. Furthermore, the HI cannot be translated to a probability that adverse effects will occur, and it is not likely to be proportional to risk. Hazard Index values (Modeled and Measured) are rounded to one decimal place and display "<0.1" for values less than 0.1 in the results columns. More information on AirToxScreen Hazard Index Level can be found on the AirToxScreen: Glossary of Terms.

Measured Hazard Levels - Aggregate

• Measured Respiratory Hazard Index
• Measured Liver Hazard Index
• Measured Developmental Hazard Index
• Measured Reproductive Hazard Index
• Measured Kidney Hazard Index
• Measured Ocular Hazard Index
• Measured Endocrine Hazard Index
• Measured Hematological Hazard Index
• Measured Immunological Hazard Index
• Measured Skeletal Hazard Index
• Measured Spleen Hazard Index
• Measured Thyroid Hazard Index
• Measured Wholebody Hazard Index

Modeled Hazard Levels - Aggregate

• AirToxScreen Respiratory Hazard Index
• AirToxScreen Liver Hazard Index
• AirToxScreen Developmental Hazard Index
• AirToxScreen Reproductive Hazard Index
• AirToxScreen Kidney Hazard Index
• AirToxScreen Ocular Hazard Index
• AirToxScreen Endocrine Hazard Index
• AirToxScreen Hematological Hazard Index
• AirToxScreen Immunological Hazard Index
• AirToxScreen Skeletal Hazard Index
• AirToxScreen Spleen Hazard Index
• AirToxScreen Thyroid Hazard Index
• AirToxScreen Wholebody Hazard Index

Pollutant Information

Parameter Code

The unique code identifying the parameter being limited and/or monitored.

Parameter Description

The description of the parameter code. Download the Parameter Reference Table (CSV) (218 K) for the complete list of parameter codes and descriptions and corresponding pollutant codes.

CAS Number

The unique code assigned by the Chemical Abstracts Service (CAS). 

Concentration from Monitoring Measurements

Average Concentration from Monitor Measurements

The average concentration is based on the modeled data source using valid daily concentration measurements from Ambient Monitoring Archive/Air Quality System over a one-year period. 

Median Concentration from Monitor Measurements

The median concentration is based on the modeled data source using valid daily concentration measurements from Ambient Monitoring Archive/Air Quality System over a one-year period. Half of the measurements in the set of data would be above this value, and the other half of the measurements would be below this value.

Maximum Concentration from Monitor Measurements

The maximum value is calculated using valid daily concentration measurements from Ambient Monitoring Archive/Air Quality System over a one-year period. The results will present the maximum annual average value. 

Concentration from AirToxScreen Model (2019)

The annual concentration derived from modeled data from AirToxScreen measurements. For more information on the AirToxScreen Assessment, see the 2019 AirToxScreen: Assessment Results page. 

Number of Daily Measurements Per Year 

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

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 AirToxScreen Technical Support Document for more information.
 

Cancer Risk Levels

See EPA's Learn About Risk Assessment webpage for a general introduction to risk assessment and common terminology. The AMS Results columns describing risk estimates based on specific datasets are defined below.

Cancer Risk from AirToxScreen Model (2019)

The AirToxScreen modeled lifetime cancer risk (in a million). A risk level of “N”-in-1 million implies a likelihood that up to “N” people out of one million equally exposed people would contract cancer if exposed continuously (24 hours per day) to the specific concentration over 70 years (an assumed lifetime). This would be in addition to those cancer cases that would normally occur in an unexposed population of one million people. Note that this assessment looks at lifetime cancer risks, which should not be confused with or compared to annual cancer risk estimates. More information on AirToxScreen Long-Term Cancer Risk can be found on the AirToxScreen: Glossary of Terms page. Information on how the modeled cancer risk is calculated is found on the AirToxScreen Frequent Questions page and and Air Toxics Technical Support Document.

Cancer Risk from Monitor Measurements

The measured lifetime cancer risk ( "N" in a million), based on exposure to average measured air pollutant concentration data, which are reported in the Air Quality System. A risk level of 1-in-1 million implies a likelihood that one person, out of one million people, would contract cancer if exposed continuously (24 hours per day) to the specific concentration over 70 years (an assumed lifetime). This would be in addition to those cancer cases that would normally occur in an unexposed population of one million people. Cancer risk values are rounded to the nearest whole number and display "<1" for values less than one in the results columns. Cancer risk can be viewed in the following statistical ranges:

Average Cancer Risk from Monitor Measurements
The average value is calculated using valid daily concentration measurements over a one- year period, and then multiplying by the cancer risk factor. This is either the calendar year or the best rolling 12-month average, depending on the selected search criteria.

Median Cancer Risk from Monitor Measurements The median value is calculated using valid daily concentration measurements over a one-year period, and then multiplying by the cancer risk factor. Half of the measurements in the yearly set of data would be above this value, and the other half of the measurements would be below this value.

Maximum Cancer Risk from Monitor Measurements
The maximum value is calculated using valid daily concentration measurements over a one-year period, and then multiplying by the cancer risk factor. The results will present the maximum annual average value.

Most Recent Cancer Risk from Monitor Measurements - most recent annual average
The most recent cancer risk applies if the user is querying over a range of years (i.e., Last 10 years or Last 5  years). The results will present the annual average for the most recent year in the selected range.

Community

Environmental Justice Indexes

EJ Indexes At or Above 80th Percentile (US – Block Group) 

Displays a count of environmental justice (EJ) indexes at or above the 80th national percentile for the Census block group that the station is located in. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field 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 home page .

 

EJ Indexes At or Above 80th Percentile (State – Block Group) 

Displays a count of environmental justice (EJ) indexes at or above the 80th state percentile for the Census block group that the station is located in. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field does not designate an area as an “EJ community.”

EJ Indexes At or Above 80th Percentile (US – 1-mile maximum) 

Displays a count of environmental justice (EJ) indexes at or above the 80th national percentile for the Census block group within a 1-mile radius of the station. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field does not designate an area as an “EJ community.”

EJ Indexes At or Above 80th Percentile (State – 1-mile maximum) 

Displays count of environmental justice (EJ) indexes at or above the 80th state percentile for the Census block group within a 1-mile radius of the station. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field does not designate an area as an “EJ community.”

Supplemental Indexes At or Above 80th Percentile (US – Block Group) 

Displays a count of supplemental indexes at or above the 80th national percentile for the Census block group that the station is located in. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field 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 home page .

 

Supplemental Indexes At or Above 80th Percentile (State – Block Group) 

Displays a count supplemental indexes at or above the 80th state percentile for the Census block group that the station is located in. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field does not designate an area as an “EJ community.”

Supplemental Indexes At or Above 80th Percentile (US – 1-mile maximum) 

Displays a count of supplemental indexes are at or above the 80th national percentile for the Census block group within a 1-mile radius of the station. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field does not designate an area as an “EJ community.”

Supplemental Indexes At or Above 80th Percentile (State – 1-mile maximum) 

Displays a count of supplemental indexes at or above the 80th state percentile for the Census block group within a 1-mile radius of the station. An "I" indicates the station is in Indian country and a "T" indicates the station is in US territories. Note that use of this field does not designate an area as an “EJ community.”

 

Demographics

Census Tract

The census tract that the station is located in. Land areas defined by the U.S. Census Bureau (2010). Tracts can vary in size but each typically contains about 4,000 residents. Census tracts are usually smaller than 2 square miles in cities, but are much larger in rural areas.

Population Density (3 mi) 

The number of persons per square mile in the profiled area. The ratio of total persons (displayed in the Total Persons field) to total land area (displayed in the Land Area field).

Percent People of Color (3 mi) 

Percent People of Color is the percentage of the population of the given area that consists of people of color. The field is calculated by subtracting the number of persons who are white (and not of Hispanic origin) from the total persons. This number is then divided by the total persons and multiplied by one hundred to determine the percentage.

Percent Low Income (3 mi) 

Percent Low Income is the percentage of the population of the given area that has an income less than two times the poverty level, based on the 2015-2019 ACS 5-Year Summary.

Statistics are shown for the area within a 3-mile radius of each station. The radius is measured from the best available lat/long coordinate. Users should be aware that demographic data are derived based upon the reported latitude and longitude of the station. Surrounding populations and other statistics were estimated by retrieving the data for Census block groups within three miles of each station.

Other

 

Distance From Tribal Land

Distance, in miles, the air monitoring station is located from the nearest tribal land. Based on EPA comparison of the air monitoring stations to the U.S. Census Bureau 2010 tribal layer data for tribes in the lower 48 states and the Bureau of Land Management Alaska State Office data for tribes in Alaska.

Non Detect Method

The non-detect method selected on the search form. ECATT offers three methodologies for handling measurements that reported or identified as "ND" (non-detects). One concentration set uses a value of zero for non-detects. The second set uses a value equal to one half of the method detection limit for non-detects. The third set, Regression on Order Statistics (ROS), uses a simple linear regression model using ordered measured (detected) values and log normal distribution to estimate the concentration of the censored (non-detected) values. For more information this methodology, see the Air Monitoring Station Data Rules and Calculations page.