What is a common source of background radiation?

Cosmic rays from outer space serve as a significant source of background radiation that affects everyone on Earth. These high-energy particles, primarily protons and atomic nuclei, enter the Earth's atmosphere and interact with atmospheric gases, leading to secondary particles that contribute to background radiation. This form of radiation is a natural phenomenon and occurs irrespective of human activity.

In contrast, while radon gas can be a notable source of indoor radiation exposure, particularly in certain geographical areas, it is considered a more localized source rather than a general contributor to background radiation across the entire planet. Industrial radioactive waste and nuclear power plants represent man-made sources of radiation that can pose environmental and health risks but are not considered standard components of background radiation, which is primarily derived from natural occurrences.