Radioactive or ionizing radiation strongly affects living organisms. People are constantly exposed to small amounts that do not cause serious harm to their health. However, stronger radiation leads to serious illness and life threatening. Therefore, a special coefficient system has been developed to measure the radiation dose.
What is radioactive radiation?
Ionizing radiation is the energy produced by atoms of radioactive substances. Sources of radiation are:
- natural origin - radioactive decay, cosmic rays, thermonuclear reactions;
- artificially created - a nuclear reactor, nuclear fuel, atomic bomb, medical equipment (for example, an X-ray machine).
Types of radioactivity
There are three types of radioactivity by origin:
- natural - inherent in heavy radioactive elements;
- artificial - intentionally created by man using the reactions of decay and synthesis of atomic nuclei;
- induced - observed in substances that have undergone severe radiation and themselves become a source of radiation.
Types of radiation
Ionizing radiation can be of three types: these are alpha rays, beta rays and gamma rays.
Alpha radiation has low penetration. Rays are a stream of helium nuclei. Almost any barrier can protect against alpha rays: clothing, skin, a sheet of paper. It is almost impossible to obtain a dangerous dose of radiation in this case, if safety precautions are followed.
Beta radiation is more dangerous for the body. It consists of a stream of electrons. Its penetration is much higher than that of alpha rays. The electron stream moves at high speed, so radiation can pass through clothes and skin, penetrating the body and causing damage to health.
Gamma radiation is the most dangerous. This is an extremely short wavelength electromagnetic radiation. Such rays have great penetrating power and are detrimental to a living organism. If the absorbed dose of such radiation exceeds the permissible threshold, then this can lead to serious illness and even death.
What is the level of exposure measured?
To calculate the radiation level, the concept of "absorbed dose" (D) is used. This is the ratio of the absorbed radiation energy (E) to the mass of the irradiated object (m). This value is expressed in two ways:
- in grays (Gy) - one gray is equal to the dose at which 1 J of energy is consumed per kilogram of substance;
- in X-rays (P) - used for x-rays and gamma rays and is approximately 0.01 Gy.
A dose of 100 P leads to dangerous health effects. A dose of 500 r is considered fatal.
The radiation level is measured by a special dosimeter.
Equivalent dose of absorbed radiation
This value is used in assessing the destructive effect of radiation on the body. It is also called the biological dose. The equivalent dose is indicated by the letter H and is calculated by the formula: H = D x k.
K is the quality factor. Using this value, the effect on the body of the type of ionizing radiation (x-ray and gamma radiation) is described.
The unit of equivalent dose of radiation is called sievert (Sv). The name is given in honor of the radiophysicist Rolf Sievert, who studied the effect of radiation on living organisms. Millisievert units (mSv) and microsievert units (ÎźSv) are also used.
An important concept is the power of an equivalent dose of N. By it is meant the rate at which the dose of N. accumulates in the body.
What doses are safe for the body? It was established that the permissible equivalent dose of H, within which pathological processes in tissues and cells do not occur, is 0.5 Sv. A single dose, leading to death, is 6-7 Sv.
A person receives microdoses of radiation from natural and artificial sources throughout his life. On average, annual doses of absorbed radiation are 2 mSv.
Danger of ionizing radiation
What happens when exposed to the body? The main danger of radioactive radiation is that its effect passes almost unnoticed. Ionizing rays do not cause pain, are not visible visually and with the help of other senses. Therefore, a person may not even be aware that he is exposed to the dangerous effects of radiation until it is too late.
Even a small exposure is dangerous for living organisms. Radiation ionizes atoms and molecules in the cells of the body. The chemical activity of cells changes, and this leads to radioactive damage to organs and tissues. Their functioning is disrupted.
The strongest radiation affects fast-dividing cells. The circulatory system and bone marrow begin to suffer first, then the digestive system and other organs.
Also, radiation has a detrimental effect on the genes in the chromosomes, leading to severe hereditary diseases or reproductive dysfunction. The most common ailment is the so-called radiation sickness.
At high equivalent doses, it can develop in the first minutes and hours after exposure. Acute radiation sickness is accompanied by symptoms such as nausea, vomiting, fever, hemorrhage.
Often, this disease is inherited. Many descendants of the victims of Hiroshima, Nagasaki and the Chernobyl accident still feel the effects of radiation sickness.
The benefits of ionizing radiation
Radioactive radiation is not only harmful. Under certain conditions, it can also benefit from it, which is actively used in various industries.
Small doses of radiation are used in medicine to treat cancer. Cells in malignant tumors are destroyed by exposure to ionizing radiation, therefore, radiation therapy is used in the treatment of cancer. Also in medicine, special drugs based on radioactive substances are used. Ionizing rays help sterilize medical devices.
The invaluable benefits of x-ray machines used to diagnose diseases and establish the degree of damage.
Ionizing radiation is used to make smoke detectors, to inspect baggage at airports and ionize air.
Radiation is also used in such industries as metallurgy, light industry, food industry, construction industry, and agriculture.
Radiation protection
When working with sources of ionizing radiation, you need to take precautions to protect the body from damage.
A simple but effective way to protect against radiation is to remove it from a radiation source. Firstly, the radiation is absorbed by air, and secondly, when moving away from the source, the radiation intensity decreases in proportion to the square of the distance.
If you cannot remove from the source, you must use other means of protection. Clothing made from special materials will become an obstacle to radiation.
Substances that absorb radiation well are lead and graphite.
Summing up, we can note the following
- radioactive radiation is of three types: alpha, beta and gamma rays;
- radiation strength varies in grays and x-rays;
- unit of equivalent dose is Sievert.
Radiation radiation causes great harm to the body, but in established doses and when used correctly, it can serve the benefit of mankind.