but not as furious as their constituents are. >> o'brien: nina totenberg, marcia coyle, two of the best court watchers in the land, thank you both very much. >> my pleasure. >> woodruff: nearly half the world's population, three billion people, cook using stoves that burn bio-mass fuel, like wood or charcoal. that seemingly-harmless act is silently killing millions every year because of regular exposure to harmful smoke. an international alliance is on a mission to reduce those deaths by distributing 100 million cleaner stoves around the world, but some health experts doubt whether those new stoves can truly save lives. as hari sreenivasan reports in a story produced with global health frontiers, researchers in ghana are trying to find the answer. >> most of our communities and households in ghana-- actually, in africa-- are rural by nature, and therefore they depend on wood to cook their food, to heat their water. >> reporter: dr. kwaku poku asante is the head of research at the kintampo health research center of the ghana health service. he's leading a study on the effects of wood smo