Next Last Index Home Text Slide 33 of 79 Radioactive materials are a natural part of our air, soil, water, rocks, building materials and food.
Cosmic radiation bombards our atmosphere constantly.
Fallout from above ground nuclear testing also contributes to your background radiation exposure. Combined, these sources result in a dose of about 300-350 mrem per person per year in Iowa. Background radiation exposure is not included as part of your occupational radiation dose.