Dominate the Mosby Protection-Safety 2026 Exam – Protect and Succeed with Confidence!

Natural background radiation provides the baseline dose everyone receives simply by living on Earth. It comes from cosmic rays, radiation in the ground and building materials (terrestrial radiation), radon gas in homes, and tiny amounts of natural radionuclides inside our bodies. When you add these natural sources together, they account for roughly half of the radiation dose people receive each year. The other half comes mainly from human-made sources, especially medical exposures like X-rays and CT scans. So the best answer is that natural background radiation makes up about 50% of human radiation exposure. The other percentages don’t reflect this common balance between natural and man-made sources.