Please see ECHO's Compliance Monitoring Expectations page for more information.

There are three main categories of stationary sources regulated by the CAA:

1. Major Sources - facilities that can emit pollutants on an annual basis at a rate greater than thresholds established by the Clean Air Act. The thresholds for a major source vary by location depending on attainment status. For example, a facility that can emit greater than 100 tons per year of any pollutant other than greenhouse gases is major under Title III of the Clean Air Act; in areas with extreme non-attainment for ozone, a facility that can emit greater than 10 tons per year of volatile organic compounds would be major under Title I of the Clean Air Act;
2. Synthetic Minor Sources (SM) - facilities that would be major but have federally enforceable permit limits to restrict their emissions below major source thresholds; and
3. Minor or Area sources - facilities that physically cannot emit above major source thresholds.

For more on the Title V permit program, please visit EPA's Operating Permits Website.

As of March 2010, there are 14,795 active major sources, and 145,236 active synthetic minor and other minor sources (collectively referred to as non-major sources). EPA does not require reporting of most minor sources and related data, with some exceptions (see Summary of Data Entry Requirements). Active sources are those that are operating, seasonal or temporarily operating. Therefore, the non-major universe count in EPA's national database does not include all minor facilities. However, some states do report minor facility data on a voluntary basis and additional facility universe data may be found on state and local agency Web sites.

The data comes from EPA and delegated state, local, and tribal environmental agencies, which report into the national data system, Air Facility System. Data for the current fiscal year and the four previous fiscal years is presented, so that we are always showing a five-year trend. The fiscal year refers to the federal fiscal year, which is from October 1 to September 30. Beginning with fiscal year 2011, the dashboards present data that was captured from EPA's data systems and frozen so that it could not be changed (any state comments regarding frozen data are posted on ECHO). For years that we do not have frozen data, we use production data (data currently in the data system). Please note that production data is subject to change as EPA's data systems are updated. We plan to eventually use frozen data for the four previous fiscal years; the current year will always be production data.

Use the ECHO Facility Search to find a facility using the facility name, address, industrial classification, or size, among other things.

Select the facility from the output list and a Detailed Facility Report will be provided that includes, among other things: 5 year history of compliance monitoring, informal enforcement actions and formal enforcement actions. For some facilities, an ICIS [Enforcement] Case Report will be available from the output list. ICIS is EPA's enforcement database of record. For the CAA, it includes only EPA data. State, tribal and local agencies do not report CAA enforcement data to ICIS.

On the ECHO Search for Facilities page under Pollutant, users can find facilities that report emissions and chemical releases to the Toxics Release Inventory and National Emissions Inventory.

• TRI data is available annually. TRI mapping and query tools are available on the TRI Data and Tools Webpage.
• NEI is updated every three years, but includes data on criteria pollutant emissions as well as hazardous air pollutants. Customizable NEI reports and maps are available at EPA's Air Emission Sources Web page.

Individual Release Reports can be looked up on TRI Explorer.

EPA maintains inventories of air quality data and facility emissions data. Air quality inventories are developed using monitoring data. Emissions inventories are developed using facility specific data. These data sets are complementary because facility emissions will affect an area's air quality.

The Air Quality System (AQS) contains air monitoring data collected by EPA, state, local and tribal air pollution control agencies from thousands of monitoring stations. To search for data, visit:

• AIRNow – Real-time air quality maps and daily AQI forecasts  for over 300 US cities.
• AirTrends – Air quality trends based on a nationwide network of monitoring sites for each criteria pollutant.
• AirCompare – Interactive Web site that provides access to air quality information, based on specific health conditions of interest.
• AirExplorer – Access to data from the AQS Data Mart for air quality analysts.
• Clean Air Status and Trends Network (CASTNET) – Access to measurements of concentrations of air pollutants involved in acidic deposition affecting regional ecosystems and rural ambient ozone levels.

The National Emissions Inventory contains source specific annual emissions data. To search data, visit:

• Air Emission Sources – Database of facility, industrial sector, county and state criteria pollutant emission summaries.

AirData provides an annual summary of air pollution data from both NEI and AQS.

The ECHO Air Facility Search allows a user to search for specific air emission sources or sources in a specific geographic area.

Areas that do not meet a National Ambient Air Quality Standard for a criteria pollutant can be found using EPA's "The Green Book Nonattainment Areas for Criteria Pollutants".

No, EPA has identified a subset of violations as federally-reportable violations (PDF) (17 pp, 5.07MB). On a voluntary basis, some states do report all violations at all emissions sources.

All deviations from a source's Title V permit are required to be reported to EPA and the permitting agency.