Traffic emissions, household cooking with wood and charcoal, waste burning and small-scale industries account for nearly three-quarters of the fine particles polluting Kigali's air, according to a new scientific study that offers the most detailed picture yet of what residents are breathing in the fast-growing city.
These fine particles are small enough to be inhaled deep into the lungs, posing serious health risks, especially to children, the elderly, and people with heart or lung conditions.
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The year-long study, led by Rwandan scientist Theobard Habineza of Carnegie Mellon University, provides the first detailed, continuous measurements of air pollution in Kigali. It was conducted in collaboration with scientists Allen Robinson, Langley DeWitt, Jimmy Gasore, Philip Croteau and Albert Presto.
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Using advanced instruments to measure fine particles and black carbon, the research sheds new light on the sources driving air pollution in one of Africa's fastest-growing cities.
Researchers relied on an Aerosol Chemical Speciation Monitor (ACSM) and black carbon measurements to identify what the airborne particles are made of and where they originate--whether from traffic emissions, fuel combustion, dust or other sources.
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"We used the latest technology to assess the air we breathe and how it affects us," Habineza said. "Air quality is poor in some parts of Kigali when compared to World Health Organisation standards."
Cooking fuels and traffic dominate emissions
Cooking with wood and charcoal remains a major contributor to air pollution. "Our findings show that cooking with wood and charcoal accounts for about 23 per cent of fine particulate matter," Habineza said.
Black carbon, a particularly harmful pollutant, comes mainly from traffic and cooking. It damages the lungs and heart and also accelerates climate change by absorbing heat in the atmosphere.
The study found that vehicles contribute about 60 per cent of black carbon emissions through fossil fuel combustion, while cooking contributes 40 per cent through biomass burning.
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Pollution levels peak during morning and evening traffic hours, at meal times, and in the dry season. Nearly half (45 per cent) of particulate matter forms in the air itself, as gases from vehicles and burning activities react in sunlight to create new particles.
"Cleaner cooking fuels are essential for improving health," Habineza said.
Car-Free Sundays show immediate gains
The study also found that air pollution drops by 17 per cent during Car-Free Sundays, underscoring the immediate benefits of reduced traffic. However, Habineza cautioned that traffic congestion following enforcement periods can worsen pollution levels.
Poor air quality increases the risk of asthma, heart disease, pregnancy complications and premature death.
"Air pollution is not only a health issue--it also slows economic growth," he said. "Reducing traffic pollution and improving cooking energy sources would cut healthcare costs, boost productivity and support a healthier urban economy."
Vehicle emission controls
Pierre-Célestin Hakizimana, an air quality inspection officer at the Rwanda Environment Management Authority (REMA), said vehicle age, type and maintenance play a critical role in emissions control.
"Vehicles under 10 years old generally comply better with emission standards than older models," he said, adding that maintenance is equally important. "A well-maintained vehicle from the 1990s can pollute less than a poorly maintained 2020 model."
The Rwanda National Police (RNP), working with other institutions, has rolled out a nationwide vehicle emission testing campaign. There are four inspection centres--Huye (south and west), Kigali (city and suburbs), Rwamagana (east) and Musanze (north).
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RNP spokesperson ACP Boniface Rutikanga said the Ndera Automobile Inspection Centre can inspect up to 650 vehicles daily, including cars, heavy machinery and motorcycles.
Push for cleaner cooking
Efforts to promote cleaner cooking are also gaining momentum. The use of electric, liquefied petroleum gas (LPG) and ethanol stoves is projected to rise from 3 per cent in 2024 to 27 per cent by 2029, under a new five-year plan by the Ministry of Infrastructure.
A new energy policy released on February 17, 2025, supports this shift by improving the availability and affordability of clean cooking solutions. The long-term goal is to phase out wood and charcoal in favour of clean and efficient fuels by 2035.
Improved cookstoves, which use less biomass fuel, are expected to increase from 9 per cent to 22 per cent by 2029.
Rwanda aims to achieve universal access to clean cooking by 2030, a move expected to reduce indoor air pollution, curb deforestation and lower health risks linked to charcoal and firewood use.
