Trillions of cigarette butts are produced worldwide every year, with most discarded into the environment. They take ages to break down while their toxic chemical load is released into creeks, rivers, and oceans. In the study, the researchers demonstrated that asphalt, or bitumen — a mixed composite material commonly used to surface roads — made with cigarette butts can handle heavy traffic and also reduce thermal conductivity.

In the study, published in a journal titled Construction and Building Materials, the team encapsulated the cigarette butts with bitumen and paraffin wax to lock in the chemicals and prevent any leaching from the asphalt concrete. The encapsulated cigarette butts were mixed with hot asphalt mix for making samples.

About six trillion cigarettes are produced every year, leading to more than 1.2 million tonnes of cigarette-butt waste. These figures are expected to increase by more than 50 percent by 2025, mainly due to an increase in world population, the study revealed. The findings can create a new construction material while ridding the environment of a huge waste problem, Mohajerani added.