Air quality sensors in rapidly growing Kenyan city improving health

The New Urban Agenda and Sustainable Development Goals (SDGs) emphasize the need to work towards safe, inclusive, and resilient cities as the world’s urban population continues to grow. It is necessary to continuously gather information from urban areas that are under-researched to learn how residents perceive and utilize city spaces as portrayed in SDG 3 on good health and well-being, SDG 7 on affordable and clean energy, and SDG 11 on sustainable cities and communities.

The deployment of PurpleAir air quality sensors is part of Phase Two of Work Package One. It seeks to link the functioning of the city and the health of its people by researching how urban residents live and their experiences through the processes that establish urban areas. The study assesses the health of urban residents through specific case studies to measure their exposure to particulate matter (PM_2.5 and PM₁₀), carbon monoxide (CO), sound levels and heart rate variabilities (HRVs). It will contribute to scientific knowledge by providing information connecting community needs to county government services through citizen science participation and developing guidelines on when and how citizen science can be used to fill information gaps and look at trends, as well as build capacity and explore future opportunities.

Nakuru is on track to become the fourth municipality in Kenya to meet the Urban Areas and Cities Act’s criteria to establish a city in Kenya.

The project has chosen four suitable sites in Nakuru, ranging from a busy location frequented by residents, a popular bus stop, a shopping mall, and a green park located within Nakuru’s central business district.

The initiative has deployed four PurpleAir (PA-II-SD) sensors across the four sites within the municipality at Nakuru County Environment Department Headquarters, Westside Mall, Nakuru County Water and Sewage Company and the newly rehabilitated Nyayo Gardens to monitor real-time PM concentrations for fine (PM_2.5) and coarse particles (PM₁₀) for four weeks to coincide with HRVs, CO and sound level measurements. PurpleAir PA-II sensors have shown moderate to good accuracy in the past compared to the reference instrument for PM₁, PM_2.5 and PM₁₀ with good data recovery, which is estimated at 95%.

The measurements are expected to fetch hourly average four-week, weekly average, and monthly average data of PM₁, PM_2.5 and PM₁₀ from the four sites. PurpleAir deployment and monitoring will report four-week baseline PM data for Nakuru to act as a reference for future measurements and the magnitude and level of pollutant concentration in the town will give indicative readings of the pollution situation in Nakuru at different locations.

The sourced PM data will contribute in part to the urban citizen science policy guidebook on how multipronged data collection co-produced with local populations and stakeholders can be used to shape urban development decisions, drawing on experiences from CHeW1 and 2 on how actions and decisions taken by urban stakeholders in Nakuru affect the health of inhabitants. PM data showing the levels of pollutants and their implications will also contribute to generating information that will go into the policy and planning document for the town of Nakuru and subsequent urban centres that may be chosen in the future.

Apart from Nakuru County activities where SEI is collaborating with the Nakuru County Government, SEI Africa is supporting the Nairobi City County Government on the development of the city county air quality regulatory framework. In addition, Sessional Paper No. 2 of 2020 on the Nairobi County Air Quality Policy and the Air Quality Bill are presently under consideration in the County Assembly together with the draft Air Quality Action Plan.

In 2019, the Climate and Clean Air Coalition and United Nations Environment Programme launched its scientific assessment on climate and clean air for Africa. SEI Africa and SEI York are two of the coordinating institutions for the Africa Assessment. SEI was also involved in producing previous assessments in Latin America and the Caribbean and Asia and the Pacific. The African Union is the other institution involved in the assessment. The data collection and measurements in Nakuru are in line with SEI research and development concerns regarding the quality of the environment. The study links well with the SEI Strategy 2020–24 target impact focused on improved health and well-being.