Simply put, radiation is a way of heat transfer, radiating from a heat source in a straight line in all directions. Of course, the propagation of electromagnetic waves such as light and radio waves is also called radiation.
All objects in nature always transfer heat in the form of electromagnetic waves and particles as long as the temperature is above absolute zero. This way of transmitting energy is called radiation. Radiation energy radiates linearly in all directions from a radiation source. The energy released by an object through radiation is called radiant energy. Radiation is calculated in roentgen (r) per hour. An important feature of radiation is "equivalence". Objects (gases) radiate outward regardless of temperature. Object A can radiate to object B, and object B can also radiate to object A. This term is usually used for ionizing radiation. Radiation itself is a neutral word, but the radiation of some substances may bring harm.
Harm to people:
Agricultural production, medical and health care, scientific research and national defense are widely used, and more and more people are exposed to radiation. The harm of radiation cannot be ignored.
nuclear radiation
Long-term radiation exposure will cause discomfort to human body, and in severe cases, it can cause damage to human organs and systems, leading to various diseases, such as leukemia, aplastic anemia, various tumors, fundus lesions, reproductive system diseases, premature aging and so on.
cosmic radiation
The harm of cosmic radiation. The intensity of cosmic radiation increases with altitude and latitude. At the altitude of 10 to 20km, the cosmic radiation intensity is nearly 100 times that of sea level. After long-term exposure to cosmic radiation, some indicators reflecting radiation damage (such as the micronucleus rate of lymphocytes in vivo) have changed, indicating that health has been affected.
electromagnetic radiation
Harm of electromagnetic radiation. Electromagnetic pollution has been recognized as the fourth public hazard after air pollution, water pollution and noise pollution. The United Nations Human Environment Conference listed electromagnetic radiation as one of the main pollutants that must be controlled. Electromagnetic radiation includes not only high-intensity electromagnetic waves generated by TV towers, mobile phones, electromagnetic wave transmission towers and other electrical equipment, but also electromagnetic radiation generated by household appliances such as computers, substations, televisions and microwave ovens. These electromagnetic radiations fill the space, are colorless, odorless and intangible, and can penetrate many substances including the human body. If the human body is exposed to radiation doses exceeding the safe level for a long time, cells will be killed or die in a large area.
According to foreign data, electromagnetic radiation has become one of the pathogenic sources that endanger human health. In the electromagnetic field, the incidence of leukemia is 2.93 times that of normal environment, and the incidence of muscle tumor is 3.26 times that of normal environment. Most experts at home and abroad believe that electromagnetic radiation is one of the causes of childhood leukemia, and can induce the proliferation of human cancer cells, affect the human reproductive system, lead to mental retardation of children, affect the human cardiovascular system, and have a negative impact on the human visual system.
Electromagnetic radiation has a great influence on elderly pregnant women. Electromagnetic radiation generated by microwave ovens, induction cookers, mobile phones, computers, photocopiers, etc. It is extremely harmful to pregnant women, especially elderly pregnant women. Taking microwave ovens as an example, the electromagnetic radiation within 50 cm of most microwave ovens exceeds the maximum limit by as much as 37%, which greatly exceeds the radiation range that even school-age pregnant women can't bear. The impact on older pregnant women can be imagined, which will greatly increase the risk of miscarriage or chromosome variation of pregnant women. Therefore, it is suggested that elderly pregnant women should stay away from the above radiation sources as far as possible during pregnancy preparation and even during pregnancy, answer the phone less, and wear radiation protection clothing in conscious unsafe environment to reduce the radiation risk.
However, experts also pointed out that there is no need to be too afraid of radiation, because radiation is not a strong carcinogen and will not cause "special cancer", which will only increase the incidence of cancer. According to the statistical analysis of existing data, only 4% of tumors are caused by ionizing radiation. Moreover, radiation injury can be prevented, and radiation injury can also be treated.
Reference: Baidu Encyclopedia-Radiation