Background radiation is present on Earth at all times. The majority of background radiation occurs naturally from minerals and a small fraction comes from man-made elements. Naturally-occurring radioactive minerals in the ground, soil, and water produce background radiation.
According to the EPA, the human body even contains some of these naturally-occurring radioactive minerals. Cosmic radiation from space also contributes to the background radiation around us.
There can be large variances in natural background radiation levels from place to place, as well as changes in the same location over time.
A small fraction of background radiation comes from human activities. Trace amounts of radioactive elements have dispersed in the environment from nuclear weapons tests and accidents, like the one at the Chernobyl nuclear power plant in Ukraine.
Nuclear reactors emit small amounts of radioactive elements. Radioactive materials used in industry and even in some consumer products are also a source of small amounts of background radiation.
OSHA’s Ionizing Radiation Safety and Health Topics include everything employers should know about health risks, standards, and prevention methods to keep workers safe.
Occupational settings with ionizing radiation sources include:
- Medical and dental offices (e.g., X-rays).
- Hospitals and outpatient treatment centers, including specialty departments in:
- Radiology (e.g., medical X-rays and computed tomography (CT) scans).
- Nuclear medicine.
- Radiation oncology.
- Interventional fluoroscopy or radiology.
- Cardiac angiography.
- Nuclear power plants (reactors) and their support facilities.
- Nuclear weapons production facilities.
- Industrial operations (e.g., radiography equipment for testing materials or products).
- Research laboratories (universities, colleges, and other scientific institutions).
- Veterinary facilities.
- Manufacturing settings and construction.
- Security operations.
- Air and space travel and transport (i.e., in-flight) operations, especially at high altitude.
- Workplaces with high levels of naturally-occurring radioactive materials (NORM), such as radon; and
- Worksites with high levels of technologically-enhanced naturally-occurring radioactive material (TENORM), such as uranium and other radioactive elements encountered during hydraulic fracturing (commonly known as “fracking”) as part of oil and gas well development.
This Ionizing Radiation Safety and Health Topics page provides a starting point for technical and regulatory information regarding the recognition, evaluation, and control of occupational health hazards associated with ionizing radiation.