NASA Sensors Reveal Addis Ababa's Black Carbon Burden

A NASA-supported network of ground sensors has produced one of the most detailed long-term assessments yet of fine-particle and black carbon pollution in Addis Ababa, giving researchers a new baseline for tracking air quality in one of Africa's fastest-growing capitals.

Scientists examined measurements collected between 2022 and 2025 at 10 monitoring sites around the Ethiopian city. The work, connected to NASA's Multi-Angle Imager for Aerosols project, found clear changes by location, season and time of day. Traffic, household fuel use and major holiday bonfires all left detectable signatures in the data.

Three years of measurements across Addis Ababa

The study focused on PM2.5, airborne particles no wider than 2.5 micrometers. These particles are small enough to travel deep into the lungs, and long-term exposure is associated with serious health risks. Black carbon is one component of PM2.5 and is produced by incomplete combustion from sources such as diesel engines, fires, charcoal and other fuels.

NASA reported that the city's three-year average PM2.5 concentration was 30 micrograms per cubic meter. That was more than three times the annual health-based standard used by the United States Environmental Protection Agency. Average black carbon levels measured in Addis Ababa were roughly four to nine times those recorded in the three U.S. metropolitan areas monitored by the same mission.

Researchers described the project as the first long-term, multisite study using continuous PM2.5 and black carbon measurements in Ethiopia. Such records are limited in many rapidly growing cities, making it difficult to identify pollution sources or measure whether policies are working.

Traffic and fuel burning shape the daily pattern

The sensor network recorded increases linked to rush-hour traffic. Pollution did not disappear after roads became quieter. Researchers also observed elevated emissions at night associated with the burning of charcoal and other fuels.

Two holidays involving bonfires produced distinct black carbon increases. The instruments were able to distinguish particles from those fires from pollution associated with fossil-fuel combustion. That level of detail can help authorities design responses around particular sources rather than treating all particulate pollution as the same problem.

The composition of PM2.5 varies from one city to another. Geography, industry, traffic and energy use all influence what residents breathe. Desert cities may have more dust, while industrial regions can record more sulfate or other combustion products. Local monitoring is therefore essential even when global health evidence is already strong.

A baseline as Ethiopia changes transport policy

The findings arrive as Ethiopia is trying to change its transport system. NASA noted that the country banned imports of internal-combustion-engine vehicles in 2024 and that cities have been adding bicycle lanes and electric-vehicle infrastructure. The new measurements can help researchers track whether those changes eventually reduce pollution.

Addis Ababa's growth makes that task urgent. The wider urban area is home to nearly six million people, and United Nations projections cited by NASA suggest the population could exceed 10 million by 2050. More residents can mean greater transport demand and energy use unless cleaner systems expand at the same pace.

Ground sensors will be paired with observations from space

NASA's MAIA research covers about a dozen metropolitan areas, including Los Angeles, Atlanta and Boston in the United States. The project already operates ground networks and is preparing a space-based observatory with a camera built by NASA's Jet Propulsion Laboratory.

The camera is expected to launch on an Italian Space Agency satellite no earlier than late 2027. It is designed to observe aerosols from multiple angles and identify different particle types by the way they reflect light. Researchers plan to combine those maps with health data to investigate relationships between specific pollutants and health outcomes.

The Addis Ababa study shows why the ground network matters before the satellite is launched. It reveals when pollution rises, where it concentrates and which sources may be responsible. When the space observations become available, scientists will have a tested local record against which to compare the wider view.

For Ethiopia, the immediate value is a clearer picture of an environmental health challenge that was previously difficult to measure continuously. For other rapidly expanding cities, the project demonstrates how sustained monitoring can turn a general concern about dirty air into evidence detailed enough to guide transport, energy and public-health decisions.