Health and Air Quality Data Pathfinder - Find Data

Air pollution is one of the largest environmental and health threats across the globe. NASA satellites and airborne platforms have instruments that observe air pollutants around the world. The data collected are being used by air quality managers and researchers studying the impact of air pollution on human health.
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Locations of burning fires (top image) compared to average monthly aerosol optical depth (bottom image). Credit: NASA Earth Observatory.

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 AOD. 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 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), aboard the joint NASA/NOAA Suomi National Polar-orbiting Partnership (Suomi NPP) satellite, also collects AOD data at a much finer spatial resolution. VIIRS uses the Deep Blue 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 remote sensing data, make sure you are choosing the best product for your area.

Research quality data products can be accessed via Earthdata Search. Data are in HDF or 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 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.

NRT data can be accessed via Worldview:

  • MODIS Aqua/Terra Combined Algorithm AOD
    The merged Dark Target/Deep Blue AOD layer provides a more global, synoptic view of AOD over land and ocean. It is available from 2000 to the present.
  • VIIRS Level 2 Deep Blue Aerosol Product
    The product uses the Deep Blue algorithm over land and the SOAR algorithm over water to determine atmospheric aerosol loading. The product is designed to facilitate continuity in the aerosol record. Deep Blue uses measurements from multiple Earth observing satellites to determine the concentration of atmospheric aerosols along with the properties of these aerosols.
  • 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.

The Applied Remote Sensing Training (ARSET) program has a Jupyter Notebook that accesses VIIRS AOD data and converts AOD to PM2.5, available through the ARSET GitHub site. For more information on using this notebook, view the MODIS to VIIRS Transition for Air Quality Applications and other Health and Air Quality Trainings.

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. 

ARSET has a Jupyter Notebook that accesses VIIRS AOD data and converts AOD to PM2.5, available through the ARSET GitHub site. For more information on using this notebook, view the MODIS to VIIRS Transition for Air Quality Applications. For more information on satellite-derived PM2.5, view Satellite Derived Annual PM2.5 Datasets in Support of United Nations Sustainable Development Goals and other Health and Air Quality Trainings.

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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 remote sensing data.

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'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.

Research quality data products can be accessed via Earthdata Search:

  • OMI NO2 data from Earthdata Search
    The OMI, aboard the Aura spacecraft, provides daily gridded and non-gridded products at 13x24 km resolution; data are in HDF5 format and can be opened using Panoply. A tutorial on using OMI NO2 data is available as a PDF and a webinar on Analyzing NO2 data within Java and Excel is available from the Earthdata YouTube website.
  • TROPOMI NO2 data from Earthdata Search
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    TROPOspheric Monitoring Instrument tropospheric vertical column of nitrogen dioxide data opened using NASA's Panoply application. The red circle indicates a change needed in the scaling factor, due to the very small numbers.

    The TROPOspheric Monitoring Instrument (TROPOMI) aboard Sentinel 5, is an ESA Mission. ESA's TROPOMI NO2 provides additional information on this level 2 data product. It is important to note that, because of the very small numbers in tropospheric vertical column of NO2, you will need to change the scaling factor in Panoply (see image from June 2018 to right). 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.

NRT data can be accessed via Worldview:

NASA also has a global nitrogen dioxide monitoring site that provides imagery of daily NO2 from OMI.

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Nishinoshima Volcano, off the coast of Japan, emits a plume of sulfur dioxide as it erupts, August 3, 2020. Data are from the Sentinel-5P TROPOspheric Monitoring Instrument (TROPOMI). Credit: NASA.

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 SO2, but in relatively smaller quantities. As with NO2, 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 SO2 is high. SO2 can also lead to acid rain.

Research quality data products can be accessed via Earthdata Search:

  • OMI SO2 Data from Earthdata Search
    OMI provides daily total column data at a resolution of 13x24 km; data are in HDF5 format, 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, aboard the Suomi NPP satellite; data are in HDF5 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
    ESA TROPOMI SO2 provides additional information on this level 2 data product. As with the NO2 data above, you will need to adjust the scaling factor. 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.

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.

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The streak of red, orange, and yellow across South America, Africa, and the Atlantic Ocean in this animation points to high levels of carbon monoxide, as measured by the Atmospheric Infrared Sounder (AIRS) instrument flying on NASA's Aqua satellite. The carbon monoxide primarily comes from fires burning in the Amazon basin, with some additional contribution from fires in southern Africa. The animation shows carbon monoxide transport sweeping east throughout August, September, and October 2005. Credit: NASA/Goddard Space Flight Center Scientific Visualization Studio.

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.

Research quality data products can be accessed via Earthdata Search:

  • AIRS CO data from Earthdata Search
    AIRS measures abundances of trace components in the atmosphere including CO. 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 format, and can be opened using Panoply.
  • MOPITT CO data from Earthdata Search
    Measurements of Pollution in the Troposphere (MOPITT) measures the amount of 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 HDF5 format, and can be opened using Panoply.
  • TROPOMI CO data from Earthdata Search
    ESA TROPOMI CO provides additional information on this level 2 data product. As with the NO2 data above, you will need to adjust the scaling factor. 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.

NRT data can be accessed via Worldview:

  • AIRS CO data in Worldview: AIRS Level 2 data are 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
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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. Credit: NASA Aura Mission.

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.

Research quality 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.

  • AIRS O3 data from Earthdata Search
    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 format, and can be opened using Panoply.
  • TROPOMI O3 data from Earthdata Search
    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.

NRT data can be accessed via Worldview:

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

 

Aerosol Index (AI) is a measurement related to AOD 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.

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

Research quality data products can be accessed via Earthdata Search.

  • OMI AI from Earthdata Search
    OMI provides an Ultraviolet Aerosol Index; data are in HDF5 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
    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.

NRT data can be accessed via Worldview:

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.

NRT data can be accessed via Worldview:

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The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this natural-color image of large clouds of smoke spreading over Sakha on August 8, 2021. Plumes of this size and opacity have been common for weeks, leading to poor air quality for many of the 280,000 people who live in the nearby city of Yakutsk. Credit: NASA Earth Observatory.

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.

Research quality data products can be accessed via Earthdata Search. All of the below data products are in HDF format, and can be opened using Panoply. The data are also customizable to GeoTIFF (see Tools for Data Access and Visualization section).

For higher resolution, the Landsat 7 Enhanced Thematic Mapper (ETM+) sensor and the Landsat 8 Operational Land Imager (OLI) instrument acquire data at 30 m spatial resolution in VNIR every 16 days (or less as you move away from the equator). Landsat 8 was developed as a collaboration between NASA and the USGS. The USGS leads satellite operations and data archiving at the Earth Resources Observation and Science center.

Landsat data can be discovered using Earthdata Search, however, you will need a USGS Earth Explorer login to download the data.

Another high resolution option is the new (but currently provisional) Harmonized Landsat and Sentinel-2 (HLS) project, which provides consistent surface reflectance and top of atmosphere brightness data from the OLI aboard the joint NASA/USGS Landsat 8 satellite and the Multi-Spectral Instrument (MSI) aboard Europe’s Copernicus Sentinel-2A and Sentinel-2B satellites. The combined measurement enables global observations of the land every 2–3 days at 30 m spatial resolution.

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.
  • HLS Surface Reflectance in Worldview

 

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The Global Annual PM2.5 Grids from MODIS, MISR and SeaWiFS Aerosol Optical Depth (AOD) with GWR, 1998–2016 consist of annual concentrations (micrograms per cubic meter) of ground-level fine particulate matter (PM2.5),with dust and sea-salt removed. Credit: SEDAC.

Air quality-related deaths and diseases that are exacerbated by air pollution are preventable, but prevention requires a knowledge of where vulnerable populations exist and what interventions are needed in those communities. Using observations of particulate matter in the air, along with socioeconomic data, can help do just that.

NASA’s Socioeconomic Data and Applications Center (SEDAC) provides a number of datasets on population exposure and vulnerability.

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Global household air pollution attributable deaths. Credit: World Health Organization.

Air pollution is a serious health issue all over the world. According to the World Health Organization (WHO), 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 ARSET courses, Fundamentals of Satellite Remote Sensing for Health Monitoring and Methods in Using NASA Remote Sensing for Health Applications.

Last Updated
Nov 5, 2021