thumb|left|The Hanford Reach of the Columbia River, where radioactivity was released from 1944 to 1971 The plutonium separation process resulted in the release of radioactive isotopes into the air, which were carried by the wind throughout southeastern Washington and into parts of Idaho, Montana, Oregon, and British Columbia. Downwinders were exposed to radionuclides, particularly iodine-131, with the heaviest releases from 1945 to 1951. These radionuclides entered the food chain via dairy cows grazing on contaminated fields; hazardous fallout was ingested by communities who consumed radioactive food and milk. Most of these airborne releases were a part of Hanford's routine operations, while a few of the larger releases occurred in isolated incidents. In 1949 an intentional release known as the "Green Run" released of iodine131 over two days. A U.S. government report released in 1992 estimated that of iodine131 had been released into the river and air from the Hanford Site between 1944 and 1947.
thumb|left|The Hanford Reach of the Columbia River, where radioactivity was released from 1944 to 1971 The plutonium separation process resulted in the release of radioactive isotopes into the air, which were carried by the wind throughout southeastern Washington and into parts of Idaho, Montana, Oregon, and British Columbia. Downwinders were exposed to radionuclides, particularly iodine-131, with the heaviest releases from 1945 to 1951. These radionuclides entered the food chain via dairy cows grazing on contaminated fields; hazardous fallout was ingested by communities who consumed radioactive food and milk. Most of these airborne releases were a part of Hanford's routine operations, while a few of the larger releases occurred in isolated incidents. In 1949 an intentional release known as the "Green Run" released of iodine131 over two days. A U.S. government report released in 1992 estimated that of iodine131 had been released into the river and air from the Hanford Site between 1944 and 1947.