2. At one extreme, the scientists estimated fly ash radiation in individuals' bones at around 18 millirems (thousandths of a rem, a unit for measuring doses of ionizing radiation) a year.
3. The average American receives 360 millirems of radiation each year, 300 from natural sources and 60 from man-made activities. (a rem is a unit of radiation exposure.)
4. The average American receives 360millirems of radiation each year, 300 from natural sources and 60 from man-made activities. (a rem is a unit of radiation exposure.)
5. The average American receives 360millirems of radiation each year, 300 from natural sources and 60 from man-made activities. (a rem is a unit of radiation exposure.)