HewaSafi, a low-cost vehicle emissions filter developed by two Kenyan teenagers using maize waste, coconut shells and algae, has won the Africa regional award in the 2026 edition of The Earth Prize.
The project, created by 17-year-olds Fredrick Njoroge Kariuki and Miron Onsarigo, received $12,500 in funding after being selected from entries across the continent in the global environmental competition for young people aged 13 to 19.
Designed for matatus and motorcycle taxis widely used across East Africa, the HewaSafi prototype uses locally sourced agricultural waste and algae to capture particulate emissions and reduce carbon monoxide and carbon dioxide output, according to the team.
The students said the idea was inspired by worsening air pollution in Kenyan urban centres including Nairobi, Naivasha and Kisumu.
“I didn’t choose this problem, it chose me,” Fredrick said in a statement issued by The Earth Foundation, the Geneva-based nonprofit behind the competition.
Air pollution contributed to an estimated 1.1 million deaths across Africa in 2019, according to the World Health Organization, with vehicle emissions a major contributor in rapidly growing cities.
The HewaSafi prototype cost about KES 16,288 ($125) to build, making it significantly cheaper than conventional emissions-control systems that often rely on expensive metals and imported components.
The team said pilot tests had already been conducted with a local matatu association and that the next phase would focus on scaling the technology with transport operators, beginning with the Eastleigh Matatu SACCO in Nairobi.
Now in its fifth year, The Earth Prize says the competition has reached more than 21,000 students across 169 countries and territories.
Public voting to select the global winner opens on May 18, with the final winner expected to be announced on May 29 through The Earth Prize.