"More than half the world’s population cooks over open fires or small charcoal or biomass stoves. These burn fuel incompletely, producing carbon monoxide and smoke that cause 1.5 million deaths a year. Envirofit’s Cookstove burns the same easily found wood but does so more completely to cut emissions by more than 80 percent and use half as much fuel. The can-shaped stove has a precisely measured opening that lets in enough air to fan the flames, yet not enough to cool it and slow down combustion. A chimney-like tube inside helps funnel in fresh air, and a ceramic lining insulates the stove to keep the fire hot and burning efficiently."