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Health and Air Quality Data Pathfinder

New to using NASA Earth data? This pathfinder is designed to help guide you through the process of selecting and using applicable datasets, with guidance on resolutions and direct links to the data sources.

After getting started here, there are numerous NASA resources that can help develop your skills further. If you are new to remote sensing, check out What is Remote Sensing? or view the Applied Remote Sensing Training on Fundamentals of Remote Sensing.

Factors causing outdoor air pollution affecting both rural and urban areas

Factors causing outdoor air pollution affecting both rural and urban areas. Source: EPA.

Pollution is caused by both anthropogenic and natural events. It’s critical for air quality managers and public health researchers to monitor air pollutants locally, regionally, and globally to further determine the risk for health conditions or diseases that are exacerbated by poor air quality. A combination of ground- and satellite-based tools provides a unique view of the globe to better understand the impacts of air pollution events. These measurements help scientists, researchers, and decision makers in forecasting events and assessing conditions in near real-time to make timely decisions.

NASA, in collaboration with other organizations, has a series of instruments that provide information for understanding a number of phenomena associated with air quality and public health. NASA’s Earth science data products are validated, meaning the accuracy has been assessed over a widely distributed set of locations and time periods via several ground-truth and validation efforts.

About the Data

About the Data

There are three main ways to use satellite data for policy applications: for qualitative applications, for quantitative applications, and for more advanced analysis. To review these three applications in more detail, check out the NASA Health and Air Quality Applied Sciences Team (HAQAST).

  1. For qualitative understanding, satellite images allow air quality managers to see and communicate spatial patterns, atmospheric transport, and trends in air pollution.
  2. Satellite data can also be used to quantify change and relative abundance.
  3. Beyond qualitative and simple quantitative calculations, satellite data support a wide range of advanced analysis, especially when combined with complementary data sources.

Particulate pollution can be measured qualitatively through visual imagery as with the Camp Fire smoke plume in the image on the left. Particulate matter and trace gases can be measured quantitatively through atmospheric column products, like the nitrogen dioxide data from the Aura Ozone Monitoring Instrument, in the image on the right.

Particulate pollution can be measured qualitatively through visual imagery as with the Camp Fire smoke plume in the image on the left. Particulate matter and trace gases can be measured quantitatively through atmospheric column products, like the nitrogen dioxide data from the Aura Ozone Monitoring Instrument, in the image on the right.

Monitoring air quality provides a means to visualize trends, forecast events or movement of pollutants, and respond to events. Aerosol Optical Depth/Thickness (AOD/AOT) provides a measurement of the quantity of light that small particles remove by absorption and scattering within a column. Absorption and scattering is caused by the composition (each element has a unique spectral fingerprint) and color of the particles (light reflects, dark absorbs). For more information on this process, check out the Earth Observatory article, Aerosols and Incoming Sunlight. AOD is not the equivalent of PM2.5 which is the measure of the mass of particles in a specific size range near surface, but with additional processing AOD provides a means of estimating PM2.5, using specific conversion techniques. Many NASA data products provide information on primary (directly emitted) and secondary pollutants (formed by chemical reactions), some of which can serve as precursors to other types of air pollution. When available, NASA’s Land, Atmosphere Near real-time Capability for EOS (LANCE) provides data to the public within 3 hours of satellite overpass, which allows for near real-time (NRT) monitoring and decision making, specifically regarding aerosol and dust indices and pollutant transport. When coupled with public health information, the air quality data can provide a valuable resource to forecasting and monitoring exposure and risk.

Datasets referenced in this pathfinder include:

Satellite

Sensor

Spatial Resolution

Temporal Resolution

Aqua

Atmospheric Infrared Sounder (AIRS) Level 2 and 3 products

1° x 1°

daily, 8-day, monthly

Terra and Aqua

Moderate Resolution Imaging Spectroradiometer (MODIS)

250m, 500m, 1km

1-2 days

Terra

Measurement of Pollution in the Troposphere (MOPITT)

1° x 1°

daily, monthly

Aura

Ozone Monitoring Instrument (OMI)

13km x 24km

daily

Suomi-NPP

Ozone Mapping and Profiler Suite (OMPS)

50km x 50km

101 minutes, daily

Sentinel 5-P

TROPOspheric Monitoring Instrument (TROPOMI)

7km x 3.5km

daily

Suomi-NPP

Visible Infrared Imaging Radiometer Suite (VIIRS)

375-750m

1-2 days

Tools for Data Access and Visualization

Tools for Data Access and Visualization

Earthdata Search | Panoply | Giovanni | Worldview

Earthdata Search

Earthdata Search provides a means of accessing all of NASA’s Earth science data across all distributed active archive centers. It provides the only means to access all data regardless of where the data are archived. Within Earthdata Search, you can subset using temporal and geographic constraints. Some data can be customized once the data of interest are selected; to do this, add the data of interest to your project and then click download all.

Screenshot of the Search Earthdata site.

In the project area, you can select to customize your granule. You can reformat the data and output as HDF, NetCDF, ASCII, KML or a GeoTIFF. You can also choose from a variety of projection options. Lastly you can subset the data, obtaining only the bands that are needed.

Earthdata Search customization tools diagram.

Panoply

HDF and NetCDF files can be viewed in Panoply, a cross-platform application that plots geo-referenced and other arrays. Panoply offers additional functionality, such as slicing and plotting arrays, combining arrays, and exporting plots and animations.

The National Snow and Ice Data Center Distributed Active Archive Center (NSIDC DAAC) has an HDF to GeoTIFF conversion tool, which allows you to geolocate, subset, stitch, and regrid certain HDF-EOS datasets.

Giovanni

Giovanni is an online environment for the display and analysis of geophysical parameters. There are a few options for analysis.

  1. Time-averaged maps are a simple way to observe the variability of data values over a region of interest.
  2. Map animations are a means to observe spatial patterns and detect unusual events over time.
  3. Area-averaged time series are used to display the value of a data variable that has been averaged from all the data values acquired for a selected region for each time step.
  4. Histogram plots are used to display the distribution of values of a data variable in a selected region and time interval.

For more detailed tutorials:

  • Giovanni How-To’s on the NASA's Goddard Earth Sciences Data and Information Services Center (GESDISC) YouTube channel
  • Data recipe for downloading a Giovanni map, as NetCDF, and converting to quantified map data in the form of lat-lon-data value ASCII text.

Worldview

Worldview is a visualization tool to interactively browse global, full-resolution satellite imagery layers and then download the underlying data. Many of the imagery layers are updated within three hours of observation, essentially showing the entire Earth as it looks "right now". View current natural hazards and events using the Events tab which reveals a list of natural events, including wildfires, tropical storms, and volcanic eruptions.

Worldview's Events tab provides information about events, such as tropical cyclones, wildfires, volcanic eruptions, and even large iceberg movement. Hurricane Barry, as shown in this image, traveled from the Gulf into Louisiana in July 2019.

Worldview's Events tab provides information about events, such as tropical cyclones, wildfires, volcanic eruptions, and even large iceberg movement. Hurricane Barry, as shown in this image, traveled from the Gulf into Louisiana in July 2019.

Animate the imagery over time. Do a screen by screen comparison of data for different time periods or a comparison of different datasets.

Hurricane Maria was a category 5 storm that devastated numerous places, most notably Puerto Rico, in September 2017. In the Woldview comparison, selecting a date pre-storm and then one post-storm shows the nighttime lights over the island, and how the storm affected electricity, even months after.

Hurricane Maria was a category 5 storm that devastated numerous places, most notably Puerto Rico, in September 2017. In the Woldview comparison, selecting a date pre-storm and then one post-storm shows the nighttime lights over the island, and how the storm affected electricity, even months after.

Find and Use Aerosol Optical Depth Data

Find and Use Aerosol Optical Depth Data
Screenshot showing 2 world maps displaying burning fires and a second map showing average monthly aerosol amounts.

Locations of burning fires (above) compared to average monthly aerosol optical depth.

Aerosol Optical Depth (AOD) is a column-integrated value of aerosols in the atmosphere obtained by measuring the scattering and absorption of solar energy from the top of the atmosphere to the surface. The non-aerosol signal of surface reflectance needs to be separated from the aerosol signal to accurately obtain an aerosol optical depth. This is challenging because the satellite instrument cannot penetrate cloud cover and highly reflective surfaces, such as ice or snow, producing misrepresentations of the data. As such, scientists have developed algorithms for the Moderate Resolution Imaging Spectroradiometer (MODIS) data to help with these effects, dark target and deep blue. For more information on these algorithms see: Dark Target Algorithm and Deep Blue Algorithm. In the latest dataset collection, these two have been merged, using the highest quality for each. While it does provide the easiest use of global coverage, there are some risks (see the websites above for more information).

The Visible Infrared Imaging Radiometer Suite (VIIRS) also collects AOD data at a much finer spatial resolution. VIIRS uses the Deep Blue (DB) algorithm over land and the Satellite Ocean Aerosol Retrieval (SOAR) algorithm over water to determine atmospheric aerosol loading for daytime cloud-free, snow-free scenes. With all of the VIIRS data, downloading a file will provide the data with just the land algorithm, just the ocean algorithm, and the merged algorithm. As with all remotely sensed data, make sure you are choosing the best product for your area.

Data Products for Measuring AOD

Science quality, or higher-level “standard” data products can be accessed via Earthdata Search. Data are in HDF (Hierarchical Data Format) or NetCDF (Network Common Data Form) format and can be opened using panoply.

Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, or a time series through an online interactive tool, Giovanni. Follow these steps to plot data in Giovanni: 1) Select a map plot type; for more information on choosing a type of plot, see the Giovanni User Manual. 2) Select a date range. Data are in multiple temporal resolutions, so be sure to note the start and end date to ensure you access the desired dataset. 3) Check the box of the variable in the left column that you'd like to include and then plot the data.

  • OMI AOD in Giovanni
    The Ozone Monitoring Instrument (OMI) on Aura has a coarser spatial resolution than MODIS and VIIRS but provides data at individual wavelengths from the ultraviolet (UV) to the visible. Within Giovanni, you can plot daily data at these individual wavelengths. This is important because pollutants have different spectral signatures; for example, a wavelength range around 400 nm can be used to detect elevated layers of absorbing aerosols such as biomass burning and desert dust plumes. The two AOD products provided through Giovanni use two different algorithms—OMI Multi-wavelength (OMAERO) and OMI UV (OMAERUV). OMI Multi-wavelength (OMAERO) is based on the multi-wavelength algorithm and uses up to 20 wavelength bands between 331 nm and 500 nm. This algorithm uses reflectances for a wide variety of microphysical aerosol models representative of desert dust, biomass burning, volcanic, and weakly absorbing aerosol types. OMI UV (OMAERUV) uses the near-UV algorithm, which is capable of retrieving aerosol properties over a wider variety of land surfaces than is possible using measurements only in the visible or near-IR, because the reflectance of all terrestrial surfaces (not covered with snow) is small in the UV.
  • MODIS AOD in Giovanni
    Provides data products with both algorithms as well as the combined algorithm at daily and monthly intervals.

Near real-time (NRT) data can be accessed via Worldview:

  • MODIS Aqua/Terra Combined Algorithm AOD
    The merged Dark Target/Deep Blue Aerosol Optical Depth layer provides a more global, synoptic view of aerosol optical depth over land and ocean. It is available from 2000 to the present.
  • OMI AOD Multi-wavelength and UV
    The multi-wavelength layer and the UV absorbing layer displays the degree to which airborne particles (aerosols) prevent the transmission of light through the process of absorption (attenuation), and the UV extinction layer indicates the level at which particles in the air (aerosols) prevent light (extinction of light) from traveling through the atmosphere. Toggling between these three can provide more distinction on the types of aerosols present.

Aerosol Optical Depth to PM2.5

Aerosol Optical Depth to PM2.5

As mentioned above, AOD is the quantity of light removed from a beam by scattering or absorbing during its path through a medium and is a unitless measure. PM2.5, on the other hand, is a measure of the mass of particles in a specific size range within a given volume of air near the surface. So there are a few differences:

  • AOD is an optical measurement, PM2.5 a mass concentration measurement.
  • AOD is an integrated column measurement from the top of the atmosphere to the surface, PM2.5 a ground measurement.
  • AOD is an area-averaged measurement, PM2.5 a point measurement.

Because the two measurements are so different, it may seem that there is no correlation. They do correlate and there are several different techniques to convert from AOD to PM2.5. It is important to note that while there is a relationship between AOD and PM2.5, there are other factors which can affect AOD, like humidity, the vertical distribution of aerosols, and the shape of the particles. For example, an increase in humidity will increase the size of particles and therefore increase the AOD even though the PM2.5 level will be the same.

The different techniques are a two-variable method, a multivariate method using neural networks, and combining satellite data, in-situ data, and models. The latter approach is the most difficult but generally preferred. For more information about the different techniques and an exercise in doing this conversion, view the course materials from the Applied Remote Sensing Training (ARSET) course, NASA Earth Observations, Data and Tools for Air Quality Applications.

Aerosol optical depth can be used as a source of particulate matter with a diameter of less than 2.5 micrometers through various mathematical methods. Moving from a two-variable method to a multi-variable method increases in complexity, thereby increasing the difficulty level.

Aerosol optical depth can be used as a source of particulate matter with a diameter of less than 2.5 micrometers through various mathematical methods. Moving from a two-variable method to a multi-variable method increases in complexity, thereby increasing the difficulty level. Source: NASA Applied Remote Sensing Training

Ground-based AOD measurements are available online at the Aerosol Robotic Network (AERONET). The Environmental Protection Agency’s ground-based PM and Ozone combined Air Quality Index (AQI) can be accessed at AirNow. AirNow International is an international program for AQI, with information provided from partnering organizations.

For trends in PM2.5, there are several resources that utilize both ground-based and remotely sensed data.

Find and Use Trace Gas Data

Find and Use Trace Gas Data

Nitrogen Dioxide | Sulfur Dioxide | Carbon Monoxide | Ground Level Ozone |

Nitrogen Dioxide

Nitrogen Dioxide (NO2) is a pollutant, the primary sources being the burning of fossil fuels, automobiles, and industry. Once in the air, it can aggravate respiratory conditions in humans, especially those with asthma, leading to an increase of symptoms, hospital admissions, and emergency visits. Long-term exposure can lead to the development of asthma and potentially increase susceptibility to respiratory infections. NO2 reacts with other chemicals in the atmosphere, forming particulate matter and ozone, producing haze and even acid rain, and contributing to nitrogen pollution in coastal waters. NASA Goddard’s Air Quality site provides more information on NO2, as well as trend maps and pre-made images of NO2 over cities and power plants.

Science quality, or higher-level “standard” data products can be accessed via Earthdata Search:

Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, or a time series through an online interactive tool, Giovanni. Follow these steps to plot data in Giovanni: 1) Select a map plot type; for more information on choosing a type of plot, see the Giovanni User Manual. 2) Select a date range. Data are in multiple temporal resolutions, so be sure to note the start and end date to ensure you access the desired dataset. 3) Check the box of the variable in the left column that you'd like to include and then plot the data.

Near real-time (NRT) data can be accessed via Worldview:

Sulfur Dioxide

Sulfur dioxide measurements from Aura's Ozone Monitoring Instrument (OMI).

Sulfur dioxide measurements from Aura's Ozone Monitoring Instrument (OMI). Source: NASA Aura

Ozone Monitoring Instrument

Sulfur Dioxide (SO2) is a pollutant of great concern; the primary sources are the burning of fossil fuels by power plants and industry. Volcanic emissions also contribute sulfur dioxide, but in relatively smaller quantities. As with nitrogen dioxide, it can aggravate respiratory conditions in humans, especially those with asthma, leading to an increase of symptoms, hospital admissions, and emergency visits. In areas where there are high levels, sulfur oxides can react with other components creating small particles which contribute to overall particulate matter, which can be ingested by humans, affecting their health, and creates lower visibility in areas where sulfur dioxide is high. SO2 can also lead to acid rain.

Science quality, or higher-level “standard” data products, can be accessed via Earthdata Search:

  • OMI SO2 Data from Earthdata Search
    Ozone Monitoring Instrument (OMI), aboard the Aura spacecraft, provides daily total column data at a resolution of 13x24 km; data are in HE5 format (Hierarchical Data Format Release 5) and can be opened using Panoply.
  • OMPS SO2 Data from Earthdata Search
    SO2 Total and Tropospheric Column data from the Ozone Mapping and Profiling Suite (OMPS) Nadir-Mapper (NM) sensor is on the Suomi-NPP satellite; data are in HE5 format and can be opened using Panoply. Note that the data are at the various atmospheric levels (planetary boundary layer, stratospheric layer, and tropospheric layers).
  • TROPOMI SO2 data from Earthdata Search
    TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel 5. TROPOMI is a European Space Agency Mission and the ESA TROPOMI SO2 provides additional information on this level 2 data product. As with the nitrogen oxide data above, you will need to adjust the scaling factor. Data are NetCDF and can be opened using Panoply.

Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, or a time series through an online interactive tool, Giovanni. Follow these steps to plot data in Giovanni: 1) Select a map plot type; for more information on choosing a type of plot, see the Giovanni User Manual. 2) Select a date range. Data are in multiple temporal resolutions, so be sure to note the start and end date to ensure you access the desired dataset. 3) Check the box of the variable in the left column that you'd like to include and then plot the data.

Near real-time (NRT) data can be accessed via Worldview:

NASA also has a global sulfur dioxide monitoring site that provides imagery of daily SO2 from OMI, OMPS, and TROPOMI. The site also provides information on the source of emissions.

Carbon Monoxide

Carbon Monoxide (CO) is a harmful pollutant that is released when something is burned, such as in the combustion of fossil fuels, the primary source, or biomass burning. Outdoor levels are rarely high enough to cause issues; when they do reach dangerous levels, however, they can be of concern to people with certain types of heart disease.

Science quality, or higher-level “standard” data products can be accessed via Earthdata Search:

  • AIRS CO data from Earthdata Search
    Atmospheric Infrared Sounder (AIRS) measures abundances of trace components in the atmosphere including carbon monoxide. Data are available daily (AIRS3STD), over 8 days (AIRS3ST8), or monthly (AIRS3STM). The instrument measures the amount of CO in the total vertical column profile of the atmosphere (from Earth’s surface to top-of-atmosphere). Data are in HDF (Hierarchical Data Format), and can be opened using Panoply.
  • MOPITT CO data from Earthdata Search
    Measurements of Pollution in the Troposphere (MOPITT) measures the amount of carbon monoxide (CO) present in the total vertical column of the lower atmosphere (troposphere) and is measured in mole per square centimeter (mol/cm2). Data are available daily or monthly. Data are acquired using the thermal and near-infrared channels. Data are in HE5 format, and can be opened using panoply.
  • TROPOMI CO data from Earthdata Search
    TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel 5. TROPOMI is a European Space Agency Mission and the ESA TROPOMI CO provides additional information on this level 2 data product. As with the nitrogen oxide data above, you will need to adjust the scaling factor. Data are NetCDF and can be opened using Panoply.

Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, or a time series through an online interactive tool, Giovanni. Follow these steps to plot data in Giovanni: 1) Select a map plot type; for more information on choosing a type of plot, see the Giovanni User Manual. 2) Select a date range. Data are in multiple temporal resolutions, so be sure to note the start and end date to ensure you access the desired dataset. 3) Check the box of the variable in the left column that you'd like to include and then plot the data.

Near real-time (NRT) data can be accessed via Worldview:

  • AIRS CO data in Worldview: AIRS Level 2 data is nominally 45 km/pixel at the equator but the data in Worldview has been resampled into a 32 km/pixel visualization.The data are in units of parts per billion by volume at the 500 hPa pressure level, approximately 5500 meters (18,000 feet) above sea level.
  • MOPITT CO data in Worldview

Ground Level Ozone

Ozone (O3) can be either good or bad, depending on where it is found in the atmosphere. In the stratosphere, O3 protects humans, plants, and animals from harmful UV radiation. In the troposphere or closer to the ground level, however, O3 serves as a potent greenhouse gas and can aggravate existing health problems in humans, especially those with respiratory illnesses. O3 is not emitted directly into the atmosphere but instead forms from the chemical reaction between nitrogen oxides and volatile organic compounds, emitted primarily from cars, power plants, and other industrial facilities; reactions take place in the presence of sunlight. Because of the need for sunlight, unhealthy levels are most often reached on very sunny days and in urban environments.

Ozone can be either good or bad, depending on where it is found in the atmosphere. In the stratosphere, ozone protects humans, plants, and animals from harmful UV radiation. In the troposphere or closer to the ground level, however, ozone serves as a potent greenhouse gas and can aggravate existing health problems in humans.

Ozone can be either good or bad, depending on where it is found in the atmosphere. In the stratosphere, ozone protects humans, plants, and animals from harmful UV radiation. In the troposphere or closer to the ground level, however, ozone serves as a potent greenhouse gas and can aggravate existing health problems in humans. Source: NASA Aura

Science quality or higher-level “standard” data products, can be accessed via Earthdata Search. There are several options and determining which to use can be a challenge.The table in About the Data may be of use as it provides information on spatial and temporal resolution.

  • OMI O3 data from Earthdata Search
    Ozone Monitoring Instrument (OMI), aboard the Aura spacecraft, provide daily total column data; data are in HE5 (Hierarchical Data Format Release 5) format and can be opened using Panoply.
  • AIRS O3 data from Earthdata Search
    Atmospheric Infrared Sounder (AIRS) measures abundances of trace components in the atmosphere including ozone. Data are available daily (AIRS3STD), over 8 days (AIRS3ST8), or monthly (AIRS3STM). The instrument measures the amount of O3 in the total vertical column profile of the atmosphere (from Earth’s surface to top-of-atmosphere). Data are in HDF ormat and can be opened using Panoply.
  • TROPOMI O3 data from Earthdata Search
    TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel 5. TROPOMI is a European Space Agency Mission and the ESA TROPOMI O3 provides additional information on this level 2 data product. Data are in NetCDF format and can be opened using Panoply.

Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, or a time series through an online interactive tool, Giovanni. Follow these steps to plot data in Giovanni: 1) Select a map plot type; for more information on choosing a type of plot, see the Giovanni User Manual. 2) Select a date range. Data are in multiple temporal resolutions, so be sure to note the start and end date to ensure you access the desired dataset. 3) Check the box of the variable in the left column that you'd like to include and then plot the data.

Near real-time (NRT) data can be accessed via Worldview:

Trends on a national and regional level are available through the Environmental Protection Agency’s Air Quality Trends.

Find and Use Pollutant Transport Data

Find and Use Pollutant Transport Data

Aerosol Index | Dust Score | Surface Reflectance |

Aerosol Index

Aerosol Index (AI) is a measurement related to Aerosol Optical Depth and indicates the presence of an increased amount of aerosols in the atmosphere. The main aerosol types that cause signals detected in this value are desert dust, significant fire events, biomass burning, and volcanic ash plumes. The lower the AI, the clearer the sky.

During one day in August, tropical cyclones, dust storms, and fires spread tiny particles throughout the atmosphere.

During one day in August, tropical cyclones, dust storms, and fires spread tiny particles throughout the atmosphere. Source: NASA Earth Observatory

Science quality, or higher-level “standard” data products, can be accessed via Earthdata Search.

  • OMI AI from Earthdata Search
    Ozone Monitoring Instrument (OMI), aboard the Aura spacecraft, provides an Ultraviolet Aerosol Index; data are in HE5 (Hierarchical Data Format Release 5) format, and can be opened using Panoply. Note that when opening the data in Panoply, there are a number of different data fields from which to choose. Select UVAerosolIndex.
  • TROPOMI AI data from Earthdata Search
    TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel 5. TROPOMI is a European Space Agency Mission and the ESA TROPOMI AI provides additional information on this level 2 data product. Data are NetCDF format and can be opened using Panoply.
  • Data products can be visualized as a time-averaged map, an animation, seasonal maps, scatter plots, or a time series through an online interactive tool, Giovanni. Follow these steps to plot data in Giovanni: 1) Select a map plot type; for more information on choosing a type of plot, see the Giovanni User Manual. 2) Select a date range. Data are in multiple temporal resolutions, so be sure to note the start and end date to ensure you access the desired dataset. 3) Check the box of the variable in the left column that you'd like to include and then plot the data.
  • OMI AI data in Giovanni

Near real-time (NRT) data can be accessed via Worldview:

Dust Score

A Dust Score indicates the level of atmospheric aerosols in the Earth’s atmosphere over the ocean. The numerical scale is a qualitative representation of the presence of dust in the atmosphere, an indication of where large dust storms may form and the areas that may be affected.

Near real-time (NRT) data can be accessed via Worldview:

  • AIRS Dust Score in Worldview
    Measurement from the Atmospheric Infrared Sounder (AIRS) Infrared quality assurance subset; the imagery resolution is 2 km.

Surface Reflectance

In comparison with the MODIS Corrected Reflectance product, the MODIS Land Atmospherically Corrected Surface Reflectance product (MOD09) is a more complete atmospheric correction algorithm that includes aerosol correction and is designed to derive land surface properties.

Science quality, or higher-level “standard” data products, can be accessed via Earthdata Search. All of the below data products are in HDF (Hierarchical Data Format) format, and can be opened using Panoply. The data are also customizable to GeoTIFF (see Tools for Data Access section below).

Near real-time (NRT) data can be accessed via Worldview:

  • MODIS Land Surface Reflectance Data in Worldview
    These images are called true-color or natural color because this combination of wavelengths is similar to what the human eye would see. The images are natural-looking images of land surface, oceanic, and atmospheric features. Some band combinations “highlight” certain types of features better than others. The information for this dataset provides more details.

Public Health

Public Health

Air pollution is a serious health issue all over the world. According to the World Health Organization, there are millions of deaths every year as a result of exposure to outdoor air pollution. In addition, 91% of the world’s population lives in places where air quality exceeds WHO guideline limits. Breathing air pollution, especially particulate matter, increases the risks of numerous illnesses, specifically respiratory, including pulmonary disease, respiratory infections, and lung cancer. It can also cause heart disease, heart attacks, and strokes. Toxicology, medicine, and epidemiology provide evidence that air pollution is impacting health across the globe. Unfortunately, evaluating toxicology and medicine does not provide a quantifiable measure of how and how much. Epidemiology, however, does, by providing a mechanism to evaluate the statistical relationships between air pollution and health due to variations in space and time

There are numerous health sites that provide information regarding public health as it relates to air pollution:

For an overview of environmental parameters available from NASA Earth Science useful for monitoring and predicting health for decision support or for more information on tools available for evaluating the relationship between environmental conditions and health outcomes, view the course materials from the Applied Remote Sensing Training (ARSET) courses, Fundamentals of Satellite Remote Sensing for Health Monitoring and Methods in Using NASA Remote Sensing for Health Applications.

Other NASA Assets of Interest

Other NASA Assets of Interest

Applied Remote Sensing Training program has numerous air quality webinars. For example, there are ones that include R and Python code for accessing and extracting data, deriving annual PM2.5, and applications for health monitoring.

Multi-Angle Imager for Aerosols (MAIA) investigation will seek to understand how different types of air pollution affect human health. MAIA is set to launch in 2022. Different epidemiological studies are planned for the primary target areas; studies in each area will focus on the health impacts associated with exposure to PM over following timescales - acute, subchronic, and chronic.

Tropospheric Emissions: Monitoring of Pollution (TEMPO) will be a geostationary mission and will measure lower tropospheric ozone, formaldehyde and nitrogen dioxide as the primary pollutant gases. TEMPO additionally measures sulfur dioxide, glyoxal, water vapor, halogen oxides, aerosols, clouds, ultraviolet-B radiation, and foliage properties. The goal is to launch in 2019

Air Quality Citizen Science is a citizen science program funded by the Earth Science Data Systems Program to add value to AOD measurements obtained by NASA's Aqua and Terra satellites. Citizen scientists are helping create a network of high quality, "low-cost" sensors in Los Angeles, California; Raleigh, North Carolina; and Delhi, India.

Citizen-Enabled Aerosol Measurements for Satellites (CEAMS) is another citizen science program funded by the Earth Science Data Systems Program to improve our understanding of how aerosols affect local air quality. Citizen scientists take backyard air quality measurements using sun photometers.

Short-term Prediction Research and Transition Center (SPoRT) is a NASA project to transition unique observations and research capabilities to the operational weather community to improve short-term forecasts on a regional scale. SPoRT provides access to numerous near real-time datasets that provide information on dust transport. Specifically the GOES-R satellite’s Advanced Baseline Imager has a dust RGB product. The SPoRT dust guide provides information on dust imagery and the interpretation.

My NASA Data Earth System Data Explorer is a data visualization tool the data has already been cataloged and formatted, so that maps of the data can be easily plotted.

External Resources

External Resources

State of the Global Air provides an interactive tool to view and compare the latest air pollution and health data, create custom maps and graphs, and download the images and data.

Global Burden of Disease out of the Institute for Health Metrics and Evaluation (IHME) is an independent population health research center at the University of Washington that provides rigorous and comparable measurement of the world's most important health problems and evaluates the strategies used to address them.

Benefits and Limitations to using Remotely-Sensed Data

Benefits and Limitations to using Remotely-Sensed Data

The United States is fortunate to have numerous ground-based measurements for assessing atmospheric particulate matter and other types of pollution, like ozone or NO2. However, this is not the case in other countries and in more rural areas of the United States. Satellite data provide a more regional to global spatial coverage; some of the information is available in near real-time, allowing for more efficient response. With satellite data, assessments can be made regarding the aerosol optical depth, which can then be correlated to PM2.5, aerosol types and aerosol transport. Incorporating satellite and in-situ data into modeling programs makes for a more robust and integrated forecasting system. Satellite data also provide enough information to determine exposure and risk categories.

Instrument measuring the vertical column of aerosol optical depth

Aerosol Optical Depth (AOD) represents the amount of aerosols in the entire column of the atmosphere. AOD is the column-integrated value from the top-of-atmosphere to surface. It can be used as a surrogate to represent particulate mass at the surface. Source: NASA Applied Remote Sensing Training

While the data provides a more global view, it’s important to note that the satellites are measuring the vertical column of air above the surface and not at ground level (where the ground-based sensors are measuring). As such, there may be some discrepancies between the two. In addition, many of the polar-orbiting satellites only pass over the same spot every 1-2 days or sometimes every 16+ days, as they are providing near-global coverage. Geostationary satellites, however, which rotate with the Earth, can monitor the fixed location as they rotate every 15-30 minutes. Finding the right instrument or understanding the modeling processes for your area of interest is key.

Last Updated: Nov 7, 2019 at 8:15 AM EST