Air Pollution Data Sources
This page provides links to data systems, maps, and additional information.
Air quality data reflects the amount of pollution and other substances present in the atmosphere measured by monitors throughout the nation.
Emissions data reflects the amount of pollutants and other substances being discharged from facilities, vehicles, and other activities that release pollution into the atmosphere.
Air Quality Data
Below is a list of systems with information about air quality. Each entry is a link followed by a description of the system and the intended audience. At the end of this section is a table providing an at-a-glance comparison of the systems.
- Air Compare - How does the air quality in my city compare with other cities? What time of year has the best air quality? Has the air quality in my city improved? AirCompare provides local air quality information to help you make informed, health-protective decisions about moving or vacationing. This area is primarily intended for the general public. It provides summary information from the Air Quality System.
- Air Data - The AirData site provides reports and maps of air pollution data for the entire United States based on criteria that you specify. This area is primarily intended for the general public. It provides summary information from the Air Quality System.
- Air Explorer - Air Explorer is a collection of user-friendly visualization tools for air quality analysts. The tools generate maps, graphs, and data tables dynamically. This area is primarily intended for air quality analysts and communications specialists. It provides summary information from the Air Quality System.
- AIRNow - The U.S. EPA, NOAA, NPS, tribal, state, and local agencies developed the AIRNow Web site to provide the public with easy access to national air quality information. AIRNow offers daily air quality forecasts as well as real-time air quality conditions for over 300 cities across the US, and provides links to more detailed State and local air quality information. This area is intended for those with an interest in the most up-to-date information about air quality and health.
- Air Quality System (AQS) - The Air Quality System is EPA's repository of ambient air quality data. AQS stores data from over 10,000 monitors; 5000 of which are currently active. State, Local and Tribal agencies collect the data and submit it to AQS on a periodic basis. This area is intended for those in the state, local and tribal agencies and within EPA who load data into the AQS database or use data from this database for analysis. Registration is required.
- Air Trends - Air Trends provides national and local air quality trends information. Data tables and reports document EPA's assessment of trends in terms of air quality, emissions, and meteorological changes over time. This area is primarily intended for technical users. It provides summary information from the Air Quality System.
- AQS Data Mart - The Air Quality System (AQS) Data Mart is a copy of the data in AQS and is available for anyone to extract information from. It contains over 1.6 billion measurements of air quality; all of those collected by EPA since 1980. This area is intended for those who need large volumes of data or need detailed information not available elsewhere. Registration is required and open to anyone.
- AQS Data Page – The most requested data from the Air Quality System (AQS) are posted on this web page. This site contains approximately 170 files of nationwide data. There is one file per year (from 1993-2006) for each of the criteria and related pollutants. The data on this page are updated 2-4 times per year. This area intended for those who need large volumes of raw air quality data.
- CASTNET - The Clean Air Status and Trends Network (CASTNET) is the nation's primary source for data on dry acidic deposition and rural, ground-level ozone. Operating since 1987, CASTNET consists of over 80 sites across the eastern and western United States and is cooperatively operated and funded with the National Park Service. This area is intended primarily for analysts who wish to download acidic deposition or ozone data from these monitors.
Comparative Tables
The following tables provide a comparison of the air quality sytems organized by intended audience. A system targeted to the general public contains information presented in a way that can be understood without detailed knowledge of the regulatory or monitoring programs. Technical users are engineers, analysts, or those employed by air quality control agencies that need more detailed information. Researcher systems are those that provide for the downloading of large amounts of data for analysis elsewhere.
Air quality information is collected and summarized on different time scales. The tables below indicate whether the system has raw data (the most detailed – hourly for continuous monitors), daily summary, or annual summary data. It gives the years of data the system contains. The substances available are also indicated in order of the most requested. Finally the types of outputs available are noted. A full circle indicates the system has this information or feature and an empty circle indicates it has some of the listed information.
General Public
System |
Level of Detail |
Time |
Substances |
Output Types |
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Raw |
Daily |
Annual |
Time range of most detailed data |
Ozone + PM2.5 |
Other Criteria |
Toxics |
PM2.5 Adj. Spec |
PM2.5 Unadj. Spec |
Other |
Tables/ Charts |
Maps |
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2000 – 2007 |
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1996 - 2007 |
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1999 – Present |
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A full circle indicates the system has this information or feature and an empty circle indicates it has some of the listed information. |
Technical Users
System |
Level of Detail |
Time |
Substances |
Output Types |
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Raw |
Daily |
Annual |
Time range of most detailed data |
Ozone + PM2.5 |
Other Criteria |
Toxics |
PM2.5 Adj. Spec |
PM2.5 Unadj. Spec |
Other |
Tables/ Charts |
Maps |
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1990 – 2007 |
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1994 – Present |
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1987 - 2006 |
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1996 – 2007 |
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A full circle indicates the system has this information or feature and an empty circle indicates it has some of the listed information. |
Researchers
System |
Level of Detail |
Time |
Substances |
Output Types |
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Raw |
Daily |
Annual |
Time range of most detailed data |
Ozone + PM2.5 |
Other Criteria |
Toxics |
PM2.5 Adj. Spec |
PM2.5 Unadj. Spec |
Other |
Tables/ Charts |
Maps |
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1994 – 2006 |
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1980 – Present |
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Emissions Data
Below is a list of systems with information about air emissions. Each entry is a link followed by a description of the system and the intended audience. At the end of this section is a table providing an at-a-glance comparison of the systems.
- Air Data - The AirData site provides reports and maps of air pollution data for the entire United States based on criteria that you specify. This area is primarily intended for the general public. It provides summary information from the Air Quality System.
- Air Emission Sources - Air Emission Sources provides summary emissions information from the national database of air pollutant emissions. This information is developed with input from numerous state and local air agencies, from tribes, and from industry. The EPA tracks a range of emissions data, including how much of each pollutant (or the pollutants that form them) is emitted from various pollution sources. This site provides national summary data, as well as state and local summaries.
- Air Emission Sources: Where You Live - This Where You Live page provides emissions information searchable through a variety of map-interfaces. At this site you can view state and county emissions summaries or create and download your own file of facility-level information. The file formats include text (CSV) and KML, which can be viewed using Google Earth or other mapping software. This area is intended for the general public and analysts who wish to learn more about the geographic location of emission sources.
- Clean Air Markets Data and Maps - The Clean Air Markets Data and Maps site provides a web-based interface to view unit, facility, emissions, and allowance data collected as part of EPA's emissions trading programs, as well as deposition data from the Clean Air Status and Trend Network (CASTNET). This area is intended for the general public and analysts who wish to learn more about emissions, related deposition, and trading of allowances in EPA’s market based programs.
- Greenhouse Gas Emissions - This section of the EPA Climate Change Site provides information and data on emissions of greenhouse gases, and also the removal of greenhouse gases from the atmosphere, including the official national inventory of U.S. greenhouse gas emissions. Governments at the federal, state and local levels prepare emissions inventories, which track emissions from various parts of the economy such as transportation, electricity production, industry, agriculture, forestry, and other sectors. This area is intended for technical users who want to learn more about greenhouse gas emissions.
- National-Scale Air Toxics Assessment (NATA) - The National-Scale Air Toxics Assessment is EPA's ongoing comprehensive evaluation of air toxics in the U.S. These activities include expansion of air toxics monitoring, improving and periodically updating emission inventories, improving national- and local-scale modeling, continued research on health effects and exposures to both ambient and indoor air, and improvement of assessment tools. Please note that air quality data presented at the NATA site is modeled and not measured.
Comparative Tables
The following tables provide a comparison of the emissions data sytems organized by intended audience. A system targeted to the general public contains information presented in a way that can be understood without detailed knowledge of the regulatory or monitoring programs. Technical users are engineers, analysts, or those employed by air quality control agencies that need more detailed information. Researcher systems are those that provide for the downloading of large amounts of data for analysis elsewhere.
Emissions information is collected and summarized on different time scales. The tables below indicate whether the system has raw data (the most detailed – hourly for continuous monitors), daily summary, or annual summary data. It gives the years of data the system contains. The substances available are also indicated in order of the most requested. Finally the types of outputs available are noted. A full circle indicates the system has this information or feature and an empty circle indicates it has some of the listed information.
General Public
System |
Level of Detail |
Time |
Substances |
Output Types |
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Raw |
Daily |
Annual |
Time range of |
Criteria |
Toxics |
Other |
Tables/ |
Maps |
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1996 - 2007 |
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2002 |
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Technical Users
System |
Level of Detail |
Time |
Substances |
Output Types |
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Raw |
Daily |
Annual |
Time range of |
Criteria |
Toxics |
Other |
Tables/ |
Maps |
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1996 & 1999 |
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