ECHO Clean Air Tracking Tool - Air Monitoring Stations

Define Year As Information

"Define Year As" allows you to select either the "Best Rolling 12 Months of Data" or "Calendar Year." EPA established the following criteria to select the Best Rolling 12 Months of Data to represent annual concentrations:

• The annual data set must comprise at least three valid quarters of data; and
• Valid quarters must have at least 70% of expected measurements for a pollutant.

See the Air Monitoring Station Data Rules and Calculations page for more information.

Ambient Pollutant Measurement Timeframe

Ambient pollutant measurement data for 2022 have not been submitted for full QA/review.  These data are also included in the results for searches on Last 10 Years and Last 5 Years.

NAAQ Standard Information

"NAAQ Standard" allows you to select only the Primary pollutant standard, only the Secondary pollutant standard, or not specify by selecting "No Restrictions." EPA established the following criteria to define the two standards:

• Primary standards provide public health protection, including protecting the health of "sensitive" populations such as asthmatics, children, and the elderly.
• Secondary standards provide public welfare protection, including protection against decreased visibility and damage to animals, crops, vegetation, and buildings.

See the EPA NAAQS Table for more information.

EJScreen Indexes for Air Monitoring Stations

Select air monitoring stations located in areas with an 80th or higher percentile of one or more of the supplemental indexes of EJScreen, EPA's screening tool for environmental justice (EJ) concerns. EPA uses these indexes to identify geographic areas that may warrant further consideration or analysis for potential EJ concerns.

Note that use of this criterion does not designate an area as an "EJ community" or "EJ facility." EJScreen provides screening level indicators, not a determination of the existence or absence of EJ concerns. For more information, see the EJScreen home page.

EJScreen Indexes: Index Type

Select from two methodologies for calculating EJScreen indexes. The indexes are a combination of environmental and socioeconomic information.

The Supplemental Index uses a five-factor demographic index that averages Percent Low Income , Percent Unemployed , Percent Limited English Speaking, Percent Less than High School Education, and Low Life Expectancy.

The Environmental Justice Index uses a two-factor demographic index that averages Percent Low Income and Percent People of Color.

EJScreen Indexes: Based On

This option selects whether the EJScreen index percentiles of a facility are calculated based on a facility’s Census block group or 1-mile maximum. The default is Census block group.

EJScreen Indexes: Compare To

This option selects whether national percentiles or state percentiles are used when determining if a location has one or more of EJScreen's indexes at or above the 80th percentile. The default is national percentiles.

AMA Site Code

The Ambient Monitoring Archive (AMA) Site Code identifies a unique Ambient Monitoring Station (AMS). Search for multiple IDs by using a comma-separated list. 

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 State code + County code + Site Code. For example: 06 (state code) + 073 (county code) + 1201 (site code) = 060731201.

Site codes are unique for stations within a county. If only a site code is provided, ECATT will display all air monitoring stations with that site code. Similarly, ECATT will display all air monitoring stations within the state or county if only a state or county code is given respectively. You can search for multiple IDs by using a comma-separated list.

Nonattainment Area

 A nonattainment area is an area that does not meet one or more of the National Ambient Air Quality Standards (NAAQS) for six commonly found air pollutants ("criteria pollutants") designated in the Clean Air Act: particle pollution (often referred to as particulate matter), ground-level ozone, carbon monoxide, sulfur oxides, nitrogen oxides, and lead.

Nonattainment areas are given a classification based on the severity of the violation and the type of air quality standard they exceed. 

Chemical Abstract Service (CAS) Number

A Chemical Abstract Service (CAS) number is a number assigned by the American Chemical Society that uniquely identifies a chemical.

Average Long-Term Cancer Risk Level

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 average 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.

When the pollutant selected is "Aggregate Pollutants" this searches for the cumulative risk for all monitored pollutants at a station. This search option allows users to identify areas of potential cancer risk and is not intended to provide a comparison between stations, as stations may monitor for different numbers and types of pollutants.

Hazard Quotient Level

Search for monitors measuring air pollutant concentrations exceeding a specific hazard quotient level. Select a specific target organ or organ system and a hazard quotient level of 1, 2, 10, 25, 50 or 100. Hazard quotient indicates the ratio of the potential exposure to an air pollutant and the level at which no adverse effects are expected. A hazard quotient less than or equal to 1 indicates that adverse effects are not likely to occur, and thus can be considered to have negligible hazard.

Compare Ambient Daily Average Measurements to Modeled Concentrations

Select "Yes" to compare the monitored pollutant concentrations to AirToxScreen modeled pollutant concentrations. Set a factor to compare 75% of ambient daily average pollutant measurements against the modeled values.  

Non-Detection Methods

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. See the Air Monitoring Station Data Rules and Calculations for more information. 

Modeled Risk Screening

AirToxScreen is EPA's comprehensive evaluation of air toxics in the United States, based on modeled air quality. These activities include the expansion of air toxics monitoring, improvement and periodic updating of emission inventories, improvement of national- and local-scale modeling, continued research on health effects and exposures to both ambient and indoor air, and improvement of assessment tools. AirToxScreen provides a snapshot of the outdoor air quality and the risks to human health that would result if air toxic emission levels remained unchanged. More information on AirToxScreen can be found on the EPA AirToxScreen Frequently Asked Questions page.

Air Toxics Cancer Risk Level

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. If you would like to compare an annual cancer risk estimate with the results in this assessment, you would need to multiply that annual estimate by a factor of 70 or alternatively divide the lifetime risk by a factor of 70.

Select a Pollutant through the lookup. Then select a Cancer Risk and risk level. For example, searching on "Formaldehyde" and "Background > 25" will return ambient emission stations where the cancer risk level for the pollutant is greater than 25 in 1 million.

Cancer Risk Types

• Background – Background pollution that exists in the air that does not come from a specific source. These pollutants may come from a natural source or from distance sources.  Background concentrations can explain pollutant concentrations found even without recent human-caused emissions.
• Biogenics – Natural sources of emissions, which include trees, plants and soil microbes.
• Fires – Emissions from fires that do not include residential wood combustion.
• Non-point – Non-point sources from the National Emissions Inventory (NEI) (https://www.epa.gov/air-emissions-inventories/national-emissions-invent…) that have geographic coordinates present in the NEI and emit at least one hazardous air pollutant. Non-point sources in the NEI are individually too small in magnitude to report as point sources.  These emissions sources are included in the NEI as a county total or tribal total (for participating tribes).  Examples include residential heating, commercial combustion, asphalt paving, and commercial and consumer solvent use.
• Non-Road – Mobile sources used on roads and highways for transportation of passengers or freight. On-road sources include:
  • passenger cars and trucks;
  • commercial trucks and buses; and
  • motorcycles
• On Road – Mobile sources used on roads and highways for transportation of passengers or freight. On-road sources include:
  • passenger cars and trucks;
  • commercial trucks and buses; and
  • motorcycles
• Point – Point sources from the National Emissions Inventory (NEI) (https://www.epa.gov/air-emissions-inventories/national-emissions-invent…) that have geographic coordinates present in the NEI and emit at least one hazardous air pollutant. Point sources in the NEI include large industrial facilities and electric power plants, airports, and smaller industrial, non-industrial and commercial facilities.  A small number of portable sources such as some asphalt or rock crushing operations are also included.
• Residential Wood – Residential wood heating, which include wood stoves and fireplaces. This source is separate from Fires due to the temporalization of this source, since the amount of wood burnt depends on the daily temperature.
• Secondary Formation – Pollutants formed by atmospheric transformation, which is the process by which chemicals are transformed into other chemicals in the air (atmosphere). When a chemical is transformed the original pollutant no longer exists; it is replaced by one or more new chemicals. Compared to the original chemical, the transformed chemical(s) can have more, less or the same toxicity. 
   

Air Toxics Hazard Quotient and Hazard Index

Hazard Quotient indicates the ratio of the potential exposure to an air pollutant and the level at which no adverse effects are expected for an organ or organ system. A hazard quotient less than or equal to 1 indicates that adverse effects are not likely to occur, and thus can be considered to have negligible hazard.

Hazard Index is the sum of hazard quotients for substances that affect the same target organ or organ system. Because different air toxics can cause similar adverse health effects, combining hazard quotients from different toxics is often appropriate. A hazard index (HI) of 1 or lower means air toxics are unlikely to cause adverse noncancer health effects over a lifetime of exposure. 

Target System

The target organ or organ system affected by the Hazard Quotient or Hazard Index. For example, searching on "Respiratory System > 2" will return the ambient monitoring stations located in areas where the hazard quotient or hazard index level is greater than 2.

Selecting Hazard Quotient and a Single Pollutant restricts the list of target systems to those affected by the pollutant.