NASA is reporting one of the most detailed long-term measurements yet of air pollution in Addis Ababa, Ethiopia. A network of 10 monitoring sites recorded particulate pollution across the capital between 2022 and 2025, giving researchers a clearer view of when black carbon rises and which activities may be contributing to it.
The findings come from NASA's Multi-Angle Imager for Aerosols, or MAIA, a project designed to study airborne particles from both the ground and space. In its official report published Aug. 17, NASA said the Addis Ababa measurements captured changes linked to rush-hour traffic, seasonal conditions and holiday celebrations involving bonfires.
What the Addis Ababa sensors found
The monitoring network focused on PM2.5, particulate matter measuring 2.5 micrometers or less across. These particles can come from several sources, including vehicle exhaust, fires, charcoal and other combustion processes. Because the sensors operated continuously at multiple locations, researchers could examine how pollution changed across the city and over time rather than relying on a single reading or short campaign.
NASA reported that Addis Ababa's three-year average PM2.5 concentration was 30 micrograms per cubic meter. The agency said that level was more than three times the annual health-based standard used by the U.S. Environmental Protection Agency. NASA also reported that average black carbon levels in Addis Ababa were approximately four to nine times higher than measurements from the three U.S. metropolitan areas included in the wider MAIA research program.
Those comparisons provide context, but they do not mean that every neighborhood or every day in Addis Ababa experienced the same conditions. The network's value is its ability to show variation: pollution can change with traffic patterns, local fuel use, weather and the timing of combustion events. A citywide average is therefore a useful baseline, not a personal exposure estimate for every resident.
Black carbon helps identify pollution sources
Black carbon is a soot-like component of fine particulate pollution produced when fuels or other materials burn incompletely. Measuring it alongside PM2.5 can help researchers distinguish between different types of pollution. The same mass of PM2.5 can have different chemical and physical characteristics depending on whether it comes from diesel engines, household fuel use, open fires or other sources.
In Addis Ababa, the MAIA network detected increases in black carbon during two major holidays that include bonfires. The researchers were able to distinguish particles associated with those fires from particles linked to fossil-fuel combustion. That distinction matters because effective air-quality action depends on knowing not only how much pollution is present, but also when and where it is being generated.
The measurements also recorded elevated emissions at night, even when traffic had declined. NASA's report describes charcoal and other fuel burning as an important contributor during those hours. This finding illustrates why traffic restrictions alone cannot explain all changes in urban air quality: different sources can dominate at different times of day.
Why the ground network matters before satellite mapping
MAIA's scientific goal is to combine surface measurements with observations from a space-based instrument. The ground sensors provide detailed local observations that can be compared with what the future observatory sees from orbit. That relationship is important because satellite measurements can cover broader areas, while ground instruments provide direct measurements at specific locations.
The planned MAIA observatory will use a JPL-built camera to examine how aerosols reflect light from multiple viewing angles. NASA says those observations are intended to help identify particle concentrations and distinguish aerosol types based on their shape, size and optical behavior. The observatory is scheduled to launch on an Italian Space Agency satellite no earlier than late 2027, so the current Addis Ababa results come from the project's ground network rather than from orbital imagery.
NASA is supporting MAIA air-pollution research in a dozen metropolitan areas, including Los Angeles, Atlanta and Boston. Comparing cities can help researchers understand which pollution patterns are local and which recur across rapidly growing urban areas. However, each city has its own geography, fuels, industries, traffic profile and weather, so the Addis Ababa baseline should not be treated as a universal model.
A measured result, not a forecast
The Addis Ababa study does not provide an air-quality forecast, prescribe a specific policy or prove that one source caused a particular health outcome. It documents measured pollution patterns and establishes a reference point against which future observations can be compared. NASA also says MAIA is the first agency project to include public-health researchers as part of a space-mission team, creating a framework for examining possible links between particle types and health data.
That makes the announcement useful beyond the Ethiopian capital. Many cities lack long-term, multisite monitoring, which limits the ability of researchers and public agencies to track change. By showing how rooftop sensors can reveal daily, seasonal and event-related patterns, the MAIA project is building the evidence needed for more targeted air-quality research while keeping the limits of the current measurements clear.
