For the first time, NASA data on nitrogen dioxide (NO2), a harmful air pollutant, is available in the Environmental Protection Agency’s (EPA) widely used Environmental Justice Screening and Mapping Tool (EJScreen). This update marks a key step in addressing air quality disparities in overburdened communities across the United States.

“Access to this accurate and localized NO2 data allows organizations like ours to understand the air quality challenges we face and better advocate for the health and well-being of our communities,” said Samuel Jordan, president of the Baltimore Transit Equity Coalition.

Previously, EJScreen included data on ozone, fine particulate matter, and various other environmental hazards. However, it lacked information on NO2, which has been linked to respiratory problems such as asthma, especially in children.

“The inclusion of NO2 data in EJScreen is a testament to how NASA’s earth science capabilities can be applied to address key societal challenges,” said John Haynes, NASA’s program manager for health and air quality. “This collaboration with EPA underscores our commitment to using space-based observations to improve public health and environmental justice.”

NO2 is emitted from burning fossil fuels and contributes to surface ozone. Communities of color and lower-income populations often live closer to highways, factories, transportation hubs, and other sources of NO2 than their wealthier counterparts. As a result, residents are exposed to higher levels of this air pollutant and others, exacerbating health inequities.

For example, a new NASA-funded study used satellite data and other information to show that nearly 150,000 storage facilities in the U.S. are increasing local NO2 levels, and they are mostly located in marginalized communities. The results reveal an average 20% increase near NO2 storage facilities, linked to truck traffic and storage density.

“NO2 is very short-lived in the air, so it’s high in the area where it’s emitted,” said Gaige Kerr, a study co-author and an air pollution researcher at George Washington University in Washington, D.C., who helped integrate NASA’s NO2 data into EJScreen. “This tool democratizes access to high-quality NO2 data, allowing people without experience in data analysis or data visualization to easily access and understand the information.”

EJScreen uses data from the Ozone Monitoring Instrument (OMI) on NASA’s Aura satellite and computer models to provide annual average NO2 estimates at the census block level. This reveals the amount of chronic NO2 present at the surface to which residents in their neighborhoods may be exposed.

“Satellite data has the potential to transform the measurement of some environmental and climate factors,” said Tai Lung, an environmental specialist at the EPA and EJScreen. “The consistency of NASA’s NO2 data for every corner of the U.S. makes it incredibly valuable for sifting through and mapping disproportionate impacts on communities.”

The dataset was developed in partnership with George Washington University, the University of Washington School of Medicine in Seattle, and Oregon State University in Corvallis. Data integration was made possible by a NASA grant to the Satellite Data for Environmental Justice Tiger Team (part of NASA’s Health and Air Quality Applied Sciences Team), which worked closely with EPA to ensure the accuracy and validity of the data.

NASA uses a variety of instruments on satellites, aircraft, and ground stations to continually collect data on key air pollutants. Scientists supported by NASA and other researchers monitor the origins, levels, and atmospheric movement of these pollutants. Their research provides key Earth observation data that can guide air quality standards, shape public policy, and inform government regulations, ultimately with the goal of improving economic and human well-being.

The Aura satellite recently celebrated its 20th anniversary. In the future, Kerr said, the team could examine NO2 data from NASA’s new TEMPO (Tropospheric Emissions: Monitoring of Pollution) instrument on the commercial Intelsat satellite.

TEMPO was launched in 2023 and offers hourly daily measurements, instead of the once-daily OMI measurements. This capability could further enhance EPA’s tool by providing insight into pollution levels throughout the day and supporting proactive air pollution management.

By Emily DeMarco
NASA’s Goddard Space Flight Center, Greenbelt, Maryland.

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