Kenya’s HewaSafi Wins Africa Earth Prize for Farm-Waste Vehicle Filter

Two Kenyan teenagers, Fredrick Njoroge Kariuki and Miron Onsarigo, have been recognised as Africa Winners of The Earth Prize 2026 for developing HewaSafi, a low-cost system designed to reduce harmful emissions from vehicle exhausts in urban areas.

The project, whose name means “clean air” in Swahili, focuses on tackling pollution from everyday transport such as matatus, buses, and boda bodas. Instead of relying on expensive industrial materials, the system is built using locally available resources like maize cobs, coconut shells, agricultural waste, and algae to help trap harmful emissions.

As part of the award, the students will receive $12,500 to further develop their idea. They will also compete with other regional winners for the global title, which will be decided through public voting between 18 and 27 May 2026, with the final result announced on 29 May.

The motivation behind HewaSafi is rooted in a real and growing problem in many Kenyan cities: transport-related air pollution. While vehicles remain essential for daily movement, especially in urban areas, they also contribute significantly to poor air quality due to emissions from petrol and diesel engines.

The system they designed works as a multi-layer exhaust filter that combines organic waste materials with a biological algae component. The aim is to reduce particulate matter and lower harmful gases produced by engines. The team claims it can capture a large percentage of pollutants, though this will require further independent testing as it moves beyond early prototypes.

Rather than assuming a full shift to electric transport in the near future, the project focuses on improving the existing fleet of vehicles already on the road. This makes it a potential “transition solution” while cleaner transport systems continue to develop in Kenya.

Both students were inspired by personal experiences. Fredrick, who grew up in Naivasha, says his respiratory health issues made him more aware of air pollution as a daily health concern rather than just an environmental issue. Miron, from Kisumu, recalls how exposure to vehicle fumes was considered normal, even though it had clear health impacts.

Air pollution remains a serious public health challenge across Africa. Research published in The Lancet Planetary Health estimates that it contributed to over a million deaths on the continent in 2019, driven by a mix of vehicle emissions, industrial activity, household fuel use, and burning waste.

Kenya has already begun experimenting with air quality awareness tools, including real-time pollution monitoring in Nairobi. However, experts often note that monitoring alone is not enough — actual emission-reducing technologies are needed to make a measurable difference.

The students have already tested early versions of HewaSafi with a local matatu group and plan to refine the design further in partnership with transport operators such as Eastleigh SACCO. They also aim to develop different versions of the system tailored to various vehicle types and budgets, including basic and advanced models.

A key part of their plan is affordability. They intend to offer instalment-based payments to make adoption easier for public transport operators, who often operate on tight margins and are sensitive to upfront costs.

However, scaling the technology will also depend on regulation and industry support. Without emissions standards or incentives, adoption may remain limited to early adopters rather than becoming widespread.

The Earth Prize itself is a global competition for young innovators focused on environmental solutions. It awards funding to student-led projects across different regions and aims to encourage practical climate innovation at a grassroots level.

Ultimately, HewaSafi highlights a broader shift in climate innovation: not only large-scale infrastructure projects, but also small, locally built technologies that aim to solve real problems in everyday environments.