The quality of air has a significant direct impact on human life (1–3). Poor urban air quality is a major and increasing concern as around 55% of the global population now live in cities, which is projected to increase to 68% by 2050 (2, 4–6). In Africa, PM2.5 exposure levels surpass the World Health Organization (WHO) 24 h health guidelines of 15 μgm−3, and the situation is projected to deteriorate further,particularly in the rapidly growing cities where there is also increasing populations (7). This projected increase in urban population will in-turn results to global rapid urbanization which poses significant environmental, social, and health risks with multiple cascading impacts across sectors and social groups (3, 8, 9). These claims have been affirmed by the World Health Organization (WHO), stating that more than 90% of people living in urban areas are exposed to air pollution levels that exceed the 2005 recommended health-based air quality guidelines hence posing threats to lives, productivity, and economies (10). This is in addition to one out of every 9 deaths globally (11). The exposure levels stem from large-scale construction, increased energy use, vehicular emissions and industrialization (12–14).
Nairobi city, the capital city of Kenya is one of the fastest-growing cities in the developing world (15). However, the city’s urbanisation growth is marred by challenges including: inadequate formal housing that results in expanding informal settlements, unplanned housing estates, and lack of coordinated planning and poor enforcement of zoning rules and regulations (4, 15–17). These challenges are a result of increasing trends in human population, vehicle population, industrial and commercial activities. To put this into perspective, the city’s rapid urbanization has seen the population grow from 4.3 million in 2018 to 5.2 million in 2022, an average annual growth rate of 3.9%. This is projected to increase to about 6 million in 2030 (18) This has led to an increase in waste generation, fumes and pollutants from combustion engines all of which play a critical role as the major city’s air pollution sources (19). Further, the US Environmental Protection Agency (EPA) states that the Nairobi air quality index (AQI) along roadside locations is at an unhealthy level (20, 21) primarily due to the high vehicular population compounded by poor transport infrastructure. Kirago et al. (22) reported that “black carbon emissions from traffic are a key stressor for air quality in Nairobi. Kiai et al. (23) reported that “ highest 24-hour average concentration of PM10 and PM2.5 was observed in Viwandani, an industrial area (111.87 μg/m3), and the lowest concentration at Karura (21.25 μg/m3), a forested area In addition, efforts to monitor and mitigate pollution don’t match the rate at which the city is developing despite the sources contributing independently to air quality (24).
Therefore there is an increasing need to understand the local air quality management ecosystem and to establish an integrated coordination platform or system to profile ongoing activities, track their impact and measure their contributions to mitigating the city’s air pollution. In addition, the need to understand the inter-sectoral linkages of air pollution sources to best manage and improve the city’s air quality is of great significance. This suggests that concerted efforts must be holistic and inclusive in improving air quality, people’s health and well-being by addressing the root causes of environmental pollution (25). Achieving this requires a coordinated cross-cutting approach spanning diverse policy domains.
To this end, the study aimed to understand the major sources of air pollution, actors within the air pollution space, the governance process, and the narratives underpinning this process. This was guided by the following specific objectives: (1) examine sectoral sources of air pollution in Nairobi city and unpacking the interlinkages among the sectors; (2) understand the governance processes underpinning air quality management including challenges and opportunities; and (3) explore strategic intervening niches that could promote effective, equitable and gender-responsive air quality management systems in Nairobi. This study is critical since the findings will contribute greatly to the air quality interventions, measurement and monitoring. Further, the information could be used to refine and update databases for air quality numerical simulations, increasing the reliability and precision of any analysis and widening the possible application of modelling for urban policy improvement.