What is the term for radiation that exists in the environment from both natural and man-made sources?

The term that describes the radiation present in the environment from both natural and man-made sources is known as background radiation. This type of radiation includes cosmic rays from outer space, radiation from the Earth itself (such as radon gas), as well as artificial sources such as medical x-rays and fallout from nuclear activities.

Background radiation is an essential concept in understanding the overall exposure individuals have to radiation in their daily lives. It helps in assessing the safety levels and establishing guidelines for radiation protection.

Other terms listed, such as electromagnetic radiation, refer more broadly to a range of radiation types including visible light and radio waves, and do not exclusively capture the essence of environmental exposure. Cosmic radiation specifically pertains to high-energy radiation from outer space and does not encompass terrestrial or artificial contributors, while ionizing radiation refers specifically to radiation that has enough energy to remove tightly bound electrons from atoms, which can come from various sources but also does not specifically define the broad environmental context. Thus, background radiation effectively encapsulates all sources of radiation encountered by individuals in their environments, making it the correct answer.