Two 17-year-old students in Kenya developed HewaSafi, an exhaust filter made from coconut shells, corn cobs, algae, and recycled battery parts. In pilot tests on five minibuses in Nairobi, the filter reduced PM2.5 particles by 93.3%, carbon monoxide by 42%, and absorbed 21.4% of CO2. The prototype costs about $126, far less than comparable filters. The project won the Africa regional prize from The Earth Prize in 2026, earning $12,500 in funding. The team plans to produce 1,200 filters with local artisans and test them across 200 vehicles. The filter uses five stages to capture different pollutants, relying on farm waste and recycled materials rather than rare earth elements or expensive catalysts. The innovation targets matatus, the minibuses that carry millions through Kenyan cities daily. While still early stage, the approach shows how low-cost, locally sourced materials can address urban air pollution without expensive supply chains.
