CASTNET is a national monitoring network established to assess trends in pollutant concentrations, atmospheric deposition, and ecological effects due to changes in air pollutant emissions. Filter pack data are reported for the time interval that the filter was exposed. Continuous measurements of gases (O3, SO2, NO, NOy, and CO) and meteorological parameters are reported as hourly averages. All data are reported in local standard time (i.e. times are not adjusted for daylight savings). Daily zero, span, and precision checks are reported for ozone and trace gases.
| Spatial Extent: | North America >> United States |
| Parameters: | |
| Date Range: | 01/13/1987 - 06/27/2024 |
| Frequency: | Weekly |
| Duration: | |
| Method: | |
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| Spatial Extent: | North America >> United States |
| Parameters: | |
| Date Range: | 01/01/1987 - 09/10/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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Annual aggregates of dry deposition flux, calculated from weekly aggregates of dry deposition velocities (MODEL_OUTPUT_WEEK) and measured concentrations (DRYCHEM_WEEK). Missing hourly deposition velocities were replaced with hourly averages, where available.
| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1987 - 01/01/2021 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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Weekly values of dry deposition concentrations and fluxes
| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/13/1987 - 06/04/2024 |
| Frequency: | Weekly |
| Duration: | |
| Method: | |
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8 Hour Average Ozone, EPA calculation
| Spatial Extent: | |
| Parameters: | 8Hr Avg Ozone |
| Date Range: | 01/01/1980 - 07/31/2024 |
| Frequency: | Daily |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | CO Gas |
| Date Range: | 01/01/1980 - 07/31/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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As part of the PM2.5 National Ambient Air Quality Standards (NAAQS) review completed in 1997, EPA established a PM2.5 Chemical Speciation Network (CSN) consisting of Speciation Trends Network (STN) sites and supplemental speciation sites. The CSN is a component of the National PM2.5 Monitoring Network, whose goal is to establish if the NAAQS are being attained. However, CSN data are not used for attainment or nonattainment decisions, but are intended to complement the activities of the larger gravimetric PM2.5 measurement network component.
| Spatial Extent: | North America >> United States |
| Parameters: | PM2.5 mass, elements, ions, and carbon species |
| Date Range: | 02/09/2000 - 06/29/2024 |
| Frequency: | 1-in-3 day |
| Duration: | 24 hours |
| Method: | Aerosol samples collected over 24 hours on Teflon and nylon filters in the MetOne SASS/SuperSASS sampler and on quartz filters in the URG3000N sampler. Teflon filters are analyzed for 33 elements, nylon filters are analyzed for ions and quartz filters are analyzed for carbon. |
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| Spatial Extent: | |
| Parameters: | NO2 Gas |
| Date Range: | 01/01/1980 - 07/31/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | Ozone |
| Date Range: | 01/01/1985 - 08/31/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | PM10 Mass |
| Date Range: | 08/21/1982 - 07/31/2024 |
| Frequency: | Daily |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | PM10 Mass |
| Date Range: | 10/28/1988 - 07/31/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for particle pollution, also called Particulate Matter (PM). PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller. Under the Clean Air Act, EPA sets and reviews national air quality standards for PM. Air quality monitors measure concentrations of PM throughout the country. EPA, state, tribal and local agencies use that data to ensure that PM in the air is at levels that protect public health and the environment. For information on PM standards, sources, health effects, and programs to reduce PM, please see the EPA Particulate Matter Pollution page.
| Spatial Extent: | North America >> United States |
| Parameters: | PM2.5 mass |
| Date Range: | 03/02/1988 - 06/30/2024 |
| Frequency: | Daily |
| Duration: | |
| Method: | |
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Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for particle pollution, also called Particulate Matter (PM). PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller. Under the Clean Air Act, EPA sets and reviews national air quality standards for PM. Air quality monitors measure concentrations of PM throughout the country. EPA, state, tribal and local agencies use that data to ensure that PM in the air is at levels that protect public health and the environment. For information on PM standards, sources, health effects, and programs to reduce PM, please see the EPA Particulate Matter Pollution page.
| Spatial Extent: | North America >> United States |
| Parameters: | PM2.5 mass |
| Date Range: | 10/01/1998 - 07/31/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
|
Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for particle pollution, also called Particulate Matter (PM). PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller. Under the Clean Air Act, EPA sets and reviews national air quality standards for PM. Air quality monitors measure concentrations of PM throughout the country. EPA, state, tribal and local agencies use that data to ensure that PM in the air is at levels that protect public health and the environment. For information on PM standards, sources, health effects, and programs to reduce PM, please see the EPA Particulate Matter Pollution page.
| Spatial Extent: | North America >> United States |
| Parameters: | PM2.5 mass |
| Date Range: | 04/04/1997 - 07/31/2024 |
| Frequency: | Daily |
| Duration: | |
| Method: | |
|
Using a nationwide network of monitoring sites, EPA has developed ambient air quality trends for particle pollution, also called Particulate Matter (PM). PM2.5 describes fine inhalable particles, with diameters that are generally 2.5 micrometers and smaller. Under the Clean Air Act, EPA sets and reviews national air quality standards for PM. Air quality monitors measure concentrations of PM throughout the country. EPA, state, tribal and local agencies use that data to ensure that PM in the air is at levels that protect public health and the environment. For information on PM standards, sources, health effects, and programs to reduce PM, please see the EPA Particulate Matter Pollution page.
| Spatial Extent: | North America >> United States |
| Parameters: | PM2.5 mass |
| Date Range: | 03/15/2008 - 09/11/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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| Spatial Extent: | North America >> United States |
| Parameters: | |
| Date Range: | 01/01/2005 - 07/29/2024 |
| Frequency: | Daily |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | SO2 Gas |
| Date Range: | 01/01/1980 - 08/31/2024 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/2004 - 12/31/2012 |
| Frequency: | Daily |
| Duration: | |
| Method: | |
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The Interagency Monitoring of Protected Visual Environments (IMPROVE) program is a cooperative measurement effort governed by a steering committee of representatives from Federal, state, and regional organizations. The IMPROVE monitoring program was established in 1985 to facilitate the creation of Federal and State implementation plans for the protection of visibility in Class I areas (156 national parks and wilderness areas) as stipulated by the 1977 amendments to the Clean Air Act.
| Spatial Extent: | North America >> United States >> Class I Areas |
| Parameters: | PM2.5 mass >> PM2.5 elemental, ionic, and carbon composition >> PM10 mass |
| Date Range: | 03/02/1988 - 02/27/2024 |
| Frequency: | 1-in-3 day |
| Duration: | 24 hours |
| Method: | Field Measurement; IMPROVE Aerosol sampler |
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Preliminary results from the IMPROVE monitoring program, meaning: No validation has been performed (or validation is incomplete), blank corrections are estimated from past data, MDL and uncertainty are not calculated, and status flags may include internal values that are not typically delivered in the final data.
| Spatial Extent: | North America >> United States >> Class I Areas |
| Parameters: | PM2.5 mass >> PM2.5 elemental, ionic, and carbon composition >> PM10 mass |
| Date Range: | 03/01/2024 - 09/30/2024 |
| Frequency: | 1-in-3 day |
| Duration: | 24 hours |
| Method: | Field Measurement; IMPROVE Aerosol sampler |
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An IMPROVE monitoring site can have missing data for various reasons, e.g. a power outage at the monitoring site. In some instances, there is enough missing data that the monitoring site fails the completeness criteria to calculate a valid haze metric for the Regional Haze Rule (RHR) baseline period (2000-2004). The RHR guidance documents has procedures for filling in some missing values with “patched” data; however this criteria is strict and few values are actually filled in. A number of States have developed different procedures to fill in additional missing values and submitted these data to the VIEWS database. These data are referred to as “substituted” data to differentiate them from the RHR “patched” data. Currently substituted data are available from 19 monitoring sites. These sites were selected because they either did not have the required 3 years of valid data to calculate the RHR haze metrics for the baseline period or they did not have complete data for the year 2002. The Regional Planning Organizations modeled the year 2002 and monitoring data was needed to evaluate and use the modeling results.
| Spatial Extent: | North America >> United States >> Class I Areas |
| Parameters: | PM2.5 mass >> PM2.5 elemental, ionic, and carbon composition >> PM10 mass >> Group 10, 50, 90 |
| Date Range: | 03/02/1988 - 12/29/2023 |
| Frequency: | 1-in-3 day |
| Duration: | 24 hours |
| Method: | Field Measurement; IMPROVE Aerosol sampler |
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An IMPROVE monitoring site can have missing data for various reasons, e.g. a power outage at the monitoring site. In some instances, there is enough missing data that the monitoring site fails the completeness criteria to calculate a valid haze metric for the Regional Haze Rule (RHR) baseline period (2000-2004). The RHR guidance documents has procedures for filling in some missing values with “patched” data; however this criteria is strict and few values are actually filled in. A number of States have developed different procedures to fill in additional missing values and submitted these data to the VIEWS database. These data are referred to as “substituted” data to differentiate them from the RHR “patched” data. Currently substituted data are available from 19 monitoring sites. These sites were selected because they either did not have the required 3 years of valid data to calculate the RHR haze metrics for the baseline period or they did not have complete data for the year 2002. The Regional Planning Organizations modeled the year 2002 and monitoring data was needed to evaluate and use the modeling results.
| Spatial Extent: | North America >> United States >> Class I Areas |
| Parameters: | PM2.5 mass >> PM2.5 elemental, ionic, and carbon composition >> PM10 mass >> Group 10, 50, 90 |
| Date Range: | 03/23/1988 - 12/29/2023 |
| Frequency: | 1-in-3 day |
| Duration: | 24 hours |
| Method: | Calculated values from measured data. |
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IMPROVE Natural Conditions II, Baseline (2000 - 2004)
| Spatial Extent: | North America >> United States |
| Parameters: | Light extinction from major aerosol components for the best and worst 20% haze days and average days |
| Date Range: | 01/01/2064 - 01/01/2064 |
| Frequency: | Once |
| Duration: | N/A |
| Method: | Calculated Aggregations |
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| Spatial Extent: | North America >> United States >> Class I Areas |
| Parameters: | |
| Date Range: | 01/01/1993 - 03/31/2023 |
| Frequency: | Hourly |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1993 - 01/01/2023 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1989 - 01/01/2023 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1993 - 01/01/2023 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1989 - 01/01/2023 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/2064 - 01/01/2064 |
| Frequency: | Once |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 10/29/2007 - 03/13/2024 |
| Frequency: | Biweekly |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 09/23/1992 - 08/28/2019 |
| Frequency: | Episodic |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 03/05/1996 - 05/28/2024 |
| Frequency: | Weekly |
| Duration: | |
| Method: | |
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NADP National Trends Network (NTN) Annual Precipitation-Weighted Mean Concentrations (PWM) in mg/L |
details |
data |
flags |
web |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1978 - 01/01/2022 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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NADP National Trends Network (NTN) Annual Precipitation-Weighted Mean Concentrations (PWM) in ueq/L |
details |
data |
flags |
web |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1978 - 01/01/2022 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 01/01/1978 - 01/01/2022 |
| Frequency: | Annual |
| Duration: | |
| Method: | |
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| Spatial Extent: | |
| Parameters: | |
| Date Range: | 07/11/1978 - 02/06/2024 |
| Frequency: | Weekly |
| Duration: | |
| Method: | |
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