Choking smoke was interrupting air and ship transportation in and around the islands of Sumatra and Borneo in early October 2006. Fires on the two islands were churning out a blanket of haze that mingled with clouds and reduced visibility to unsafe levels. In addition to their immediate impacts on air quality and human society, fires in tropical lowland forests affect increasingly threatened habitat for rainforest plants and animals, including the endangered orangutans. And because they release significant amounts of carbon dioxide and particle pollution, such as soot, the fires affect the global climate.