Radiation usually refers to rays with a certain energy, he can destroy cellular tissue, thus causing harm to the human body, the greater the intensity and energy of the rays, the longer the exposure time, the greater the harm to the human body. When the human body is exposed to a large amount of radiation, symptoms such as dizziness, loss of appetite, nausea, vomiting and other symptoms may occur, which may lead to serious damage to the body, or even death. However, when the human body is only exposed to a small amount of radiation (for example, from natural background radiation and medical examinations), there will be no discomfort and no harm to the body.