Nairobi, April 13 -- On chilly days, many outdoor workers in towns and markets turn to street coffee-popularly known as kahawa chungu (bitter coffee)-to stay warm.

The beverage-made by boiling water mixed with sugar and spiced coffee-is often served in small paper cups, sometimes accompanied by snacks like mandazi or samosa. Vendors target commuters, boda boda operators, jua kali artisans and night shift workers.

The drink costs less than Sh20 and is affordable for most customers. But its consumption is often a threat to the environment. In Homa Bay County, it is served in single-use plastic cups. Most people either leave the cups on the ground or just toss them into drainage systems after use.

Plastic water bottles, single-use plastic...