DAR ES SALAAM, Oct. 21 -- EVERY day, households and businesses use roads, water, energy and other natural resources that support economic activity.

At the same time, some of these activities generate waste, air pollution, contaminated water, plastic waste and other forms of environmental damage.

The costs of that damage, however, are often not paid directly by those who cause it. Instead, they can be transferred to the wider public through polluted neighbourhoods, damaged ecosystems, increased healthcare needs and public funds required to clean up environmental problems.

This raises a simple question: who should pay for the environmental costs created by economic activity? One answer is captured in the principle known as “the pol...