Other old technologies continue to be a problem. The World Health Organization has found that almost two million people perish every year from the effects of indoor smoke—from burning coal or wood or dung inside the home. And Rick Hind, legislative director at Greenpeace, wonders whether the greatest risks might be those we don't yet understand. There are 60,000 or 70,000 chemicals in commercial use, he explains, yet only about 200 have been thoroughly assessed by the EPA. "A very small percentage of the chemicals that we're swimming in—in our air, our water, and our food—have been tested for all the things that they can do to us," he says. That means the worst pollutant in the world may not yet be known.