Nairobi, Kenya’s capital, is among the three largest East African cities and serves as the region’s economic and transport hub. It is home to an estimated 5.3 million inhabitants, projected to increase to ~8 million by 2035.
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Compared to its neighbouring capital cities, Nairobi has a more mature and developed services sector. The city ranks first in the region on the Global Business Cities Index 2022 and fifth across the African continent. It is the city of choice for many major telecoms and financial service firms, including Safaricom and Standard Chartered Bank, as well as real estate, tourism, and light manufacturing businesses (e.g., processed foods, beverages, and cigarettes). Nairobi was also ranked as the fourth most popular tourist destination in Africa and first in the region with ~1.8 million visitors per year. In addition to this, the city has gained a reputation for its tech ecosystem; Kenya’s digital economy has experienced an average annual growth rate of 10.8% since 2016, earning the country the nickname ‘Silicon Savannah’.
Nairobi’s economy is characterised by a formal sector (representing 80% of Kenya’s registered businesses) and a thriving informal economy, drawing on the energy and ingenuity of workers who primarily reside in the city’s sprawling informal settlements. Around 60% of Nairobi’s citizens live in these areas, which cover only 5.2% of the total residential area. Air pollution in the city, which in 2019 was 4.2 times higher than WHO recommended average annual concentration levels, is the results of both formal and informal activities. Poor air quality stems from reliance on unclean cooking fuels, improper waste management, and highly-polluting small-scale industries, primarily in informal settlements such as Kibera, Africa’s largest slum. In contrast, Nairobi’s traffic problems stem mainly from the city’s urban elites, as ~88% of the traffic on major highways comes from passenger vehicles, despite only 15% of households owning cars. This situation earned Nairobi the title of the fourth most congested city globally in 2019.
The Nairobi City County Government has recently taken major steps to manage air pollution. This includes the development of an Air Quality Action Plan, spurred by the mayor’s prioritisation of the issue. While some areas still require further development in tackling air pollution, the city has made considerable progress by creating strong partnerships with private and international actors, investing in air quality data collection and management, and enshrining air pollution action into law. These efforts help ensure Nairobi’s long-term commitment to addressing air pollution challenges, although much work remains to be done.
Major sources of air pollution
Transport
The main source of Nairobi’s PM2.5 concentrations is road transport (40%). This is primarily due to the presence of a large and aged vehicle fleet, inadequate road networks, and poorly enforced vehicle emission standards. Despite accounting for only ~9% of the population, the city hosts over a third of the country’s ~3m vehicle fleet. However only 12.8% of Nairobi residents possess vehicles, which suggests this figure is driven by high ownership rates amongst wealthier urban residents. In contrast, around 70% of residents rely on public transport buses (matatus) for travel, most of which are elderly (16 years old on average), second-hand imported vehicles with low fuel efficiency. This, coupled with the city’s inadequate transport network, makes Nairobi one of the world’s most gridlocked cities, particularly during rush hour, where the city’s population grows from around 4.5 million to over 6 million.
Recognizing these challenges, the city has developed an Integrated Urban Development Master Plan (NUIPLAN), which includes actions to improve the quality and green credentials of road and public transit systems. In April 2023, Nairobi secured a €348 million financing agreement with the European Commission to develop the first dedicated electric bus rapid transit system in East Africa, joining the ranks of other African cities with rapid transit measures, such as Dar Es Salaam, Dakar, Lagos and Johannesburg.
Mismanagement of waste
Another cause of air pollution in Nairobi is the illegal dumping and burning of waste, which contributes 25% of PM2.5 concentrations. The city generates 3,000 t/day of solid municipal waste, of which 62% is illegally disposed. Dandora, the largest landfill, receives ~2000 tonnes of waste daily, despite being deemed full since 2001, leading to methane emissions and spontaneous combustion fires.
Around 250 public health facilities generate ~150 tonnes of medical waste, but with only one licensed incinerator (with a capacity of 6 tonnes/month), most waste is burnt in unlicensed facilities or open-air burnings at night to avoid detection.
Efforts to improve waste management include a 2015 National Solid Waste Management Strategy, setting guidelines for collection, transportation, disposal, and licensing. A recent law penalizes public waste disposal without authorization with a minimum fine of KSH 500,000 (equivalent to $3,500) or imprisonment for at least 6 months.
Biomass fuel burning
Lower-income groups in Nairobi’s informal settlements heavily rely on solid fuels for heating and cooking due to the higher cost and unequal access associated with clean fuels and electricity. The use of unclean biomass fuels contributes ~15% of PM2.5 concentrations. Only ~13.4% of city residents have access to clean fuel sources, with 63.2% using paraffin for cooking. Nairobi has over 150 informal settlements, the largest being Kibera, where emissions from unclean cooking contribute to PM2.5 concentrations as high as 214 μg/m3 within homes, ~43 times above WHO’s recommended exposure limits.
Countrywide, efforts focus on educating citizens about indoor air pollution dangers. The government, supported by Modern Energy Cooking Services (MECS) and EED Advisory, is developing the Kenya National Clean Cooking Strategy (KNCCS) to achieve universal access to clean cooking by 2028. Additionally, a 2021 facilitators guide for Community Health Volunteers (CHV) was launched to educate vulnerable groups on the dangers of household air pollution and provide preventative solutions for cooking, heating, and lighting.
Other causes of air pollution
Industrial processes significantly contribute to Nairobi’s PM2.5 concentrations (~15%), mainly due to poor practices prevalent in informal industries like metal recycling and iron smelting in central districts. Activities like cement production on the outskirts of Athi River and tanneries at the city’s periphery also add to PM2.5 concentration levels. Other polluting industries include cigarette and galvanised steel production, and agricultural processing.
Health and financial impact of air pollution in Nairobi
The visualisation above shows the financial cost of air pollution in 2019, accrued through premature mortality and absenteeism, and the projected impacts under a business-as-usual scenario.
Approximately 2,500 premature deaths (roughly 15% of the total) were attributable to air pollution in Nairobi in 2019. Air pollution exacerbates lower respiratory infections which are the fourth most important cause of death and disability combined in Kenya.
The health impacts of air pollution are disproportionately felt by those on the lowest incomes, as densely populated informal settlements often occupy marginal lands near large roads and industrial facilities.
Nairobi is among the leaders in the region in terms of progress on addressing air quality challenges. However, further work is still needed in developing regulations to implement its air quality policies and changing behaviour around waste disposal and unclean fuel use.
Impact of clean air policies that reduce air pollution and GHG emissions
The cumulative impact between 2023-2040 from implementing the identified clean air interventions could save Nairobi ~$192m, which equates to 23% of the Kenyan government’s total health expenditure in 2022 (~$850m). A further 2,100 deaths could be reduced, as well as GHG emissions abated by 49Mt of CO2e, equivalent to ~38% of Kenya’s current GHG emissions.
To help maintain its place as a top choice for East African HQs, regional talent, and tourism, Nairobi needs to further reduce air pollution. Residents, tourists, and workers need incentives to live, stay and work in its growing services sector, which accounts for 34% of GDP.
More importantly, Nairobi faces the risk of further exacerbating health disparities between residents of formal and informal settlements if it fails to address the knowledge gap of lower income groups who, without better information, will continue to choose dirty cooking fuels. The government has rolled out training for local community health workers (CHWs) and volunteers about air pollution. This aims to empower them to educate others on ways to reduce exposure to PM2.5 during routine visits in their local communities.
The city has already taken several measures to combat air pollution, including instituting the Nairobi City County Air Quality Bill (2021), a Climate Action Plan (CAP), and partnering with the World Resource Institute (WRI) to conduct an emissions inventory. However, more can still be done. Nairobi is in the process of installing networks of locally developed low-cost sensors to gather and share data. It is also becoming the host of Clean Air Catalyst’s third pilot project, working with local authorities to improve air quality monitoring and data collection in the most impacted communities. In the future, Nairobi plans to further enhance air quality communication as well as update its strategies for building codes and renewable energy as it aims to reach net-zero energy production by 2050.
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