Contents
Radioactive radiation surrounds us everywhere, to some extent all objects and even the person himself have it. It is not the radiation itself that is dangerous, but when its value exceeds certain values. It is one thing if a person has been exposed to radiation for a short time, and quite another when it affects a long time, for example, lives in a contaminated apartment. Looking ahead, let’s say that for a person, a safe radiation rate is defined within 30 microroentgens per hour (μR / h). There are several other units of measurement. Other norms and units of its measurement will be discussed below.
What is radiation
Radiation is a type of radiation emitted by charged particles. Such radiation, acting on surrounding objects, ionizes the substance. In the case of humans, it not only ionizes cells, but also destroys them or causes cancer.
Most of the elements of the periodic table are inert and harmless, but some of them have an unstable state. Without going into details, you can describe it like this. The atoms of some substances break apart due to fragile internal bonds. This decay is accompanied by the release of alpha, beta particles and gamma radiation.
Such a release is accompanied by the release of energy with different penetrating power and having a different effect on the tissues of the body.
Types of radiation
There are several types of radioactivity that can be divided into non-dangerous, low-dangerous and dangerous. We will not dwell on them in detail, rather it is for understanding what you can encounter indoors. So this is:
- alpha (α) radiation;
- beta (β) radiation;
- gamma (γ) radiation;
- neutron;
- x-ray.
Alpha, beta, and neutron radiation are particle irradiation. Gamma and X-rays are electromagnetic radiation.
In everyday life, you are unlikely to meet with x-ray и neutron, since they are specific, but with the rest you can. Each of these types of radiation has a different degree of danger, but, in addition, it must be taken into account how much radiation a person has received.
How is radiation measured?
There are several units of radiation measurement, but in general, at the user level, the x-ray associated with it is preferred. They are shown in the table below. We will not consider them in detail, since if necessary, only 2 will be needed to find out the radioactive background in the apartment.
- Sievert is the equivalent dose. 1 Sv u100d 100 R u1d XNUMX REM uXNUMXd XNUMX Gy.
- Renten — external unit — Kl/kg. 1 P = 1 BER = 0,01 Zv.
- BRIDE – an analogue of the Sievert, an obsolete non-systemic unit. 1 REM u1d 0,01 R uXNUMXd XNUMX Sv.
- Gray – absorbed dose rate – J/kg. 1 Gy = 100 Rad.
- Rad is the dose of absorbed radiation J/kg. 1 rad is 0,01 (1 rad = 0,01 Gy).
In practice, the system unit Sievert (Sv), mSv – millisievert, μSv – microsievert, named after the scientist Rolf Sievert, is more in use. Sievert is a unit of measurement of equivalent dose, expressed as the amount of energy received per kilogram of mass J / kg.
The expression for radiation in Roentgens is also used, although less widely. However, converting roentgens to sieverts is not difficult.
1 Roentgen is equal to 0,0098 Sv, but usually the value in sievert is rounded up to 0,01, which simplifies the conversion. Since these are very large doses, in reality they use much lower values of m – milli 10-3 and mk – micro 10-6 . Hence 100 μR = 1 μSv, or 50 μR = 0,5 μSv. That is, a factor of 100 is used. When you need to convert microsieverts to microroentgens, you need to multiply some value by one hundred, and if you need to convert x-rays to sieverts, then you need to divide.
Supervision and regulations
Supervision in this area is carried out by Rospotrebnadzor by special services. Control over the state of radioactive contamination of the environment is carried out by the Federal Service of Russia for Hydrometeorology and Environmental Monitoring, and over the level of radiation safety of the population – by the bodies of the Ministry of Health of the Russian Federation.
In Russia, radiation doses for humans are established by SanPiN 2.6.1.2523-09 “Radiation Safety Standards NRB-99/2009” and OSPORB-99. According to them, the maximum permissible dose of radiation for a person is no more than 5 mSv or 0,5 REM, or 0,5 R per year.
Norms for a person
Over the long years of radiation research, safe and maximum doses have been determined. Unfortunately, not only empirically, but also in practice. Events such as Hiroshima and Chernobyl were not in vain for the planet. Years of observation of radiation have shown that exceeding the permissible dose of radiation leaves an imprint on all subsequent generations.
Radiation background
4,5 billion years have passed since the birth of the earth, during which time the radioactivity, which at the time of its formation was simply gigantic, has almost vanished. The existing natural background, which in our country is 4-15 microR per hour, consists of several components. This:
- Natural, up to 83%. Residual radiation from natural sources – gases, minerals.
- Cosmic radiation – 14%. The most powerful source of radiation is the sun. With a decrease in the earth’s magnetic field, the general background will increase, which can lead to an increase in cancers and mutations. The second factor that reduces radiation is the atmosphere. Airplane pilots and mountain climbers receive an increased dose.
- Technogenic – from 3 to 13%. 75 years have passed since the first atomic explosion. During the testing of atomic weapons, a huge amount of radioactive substances was released into the atmosphere. In addition, man-made accidents – Chernobyl, Fukushima. Extraction and transportation of such substances, as well as operating nuclear power plants. Everything contributes to the overall background.
The norm of background radiation is a value up to 0,20 µSv/h or 20 µR/h. Permissible background is considered to be a level up to 60 µR/h or 0,6 mSv. For each country, it sets its own, for example, in Brazil, the safe radioactive background is 100 microR per hour.
safe dose
A safe dose of radiation for a person is the level at which one can live and work without consequences for the body. This level is defined up to 30 µR/h (0,3 µSv/h).
Permissible dose
The allowable dose of radiation is slightly more than safe and indicates the level at which the body is exposed to radiation, but without negative health effects.
Permissible level per year assumes up to 1 mSv. If this value is divided by hours, we get 0,57 µSv/h.
This dose is also used to calculate the average value of the received radiation over several years. For example, a person for 5 years in a row should receive 5 mSv, but working in hazardous industries, he received an annual of 3 mSv. For the next 4 years, he should not receive more than 1 mSv in order to equalize the values and reduce the risk of developing radiation sickness.
When flying at an altitude above 10 km, the radiation level will be up to 3 μSv / h, which exceeds the norm by 10 times. It turns out that in 4 hours you can get the maximum, total dose of up to 12 μSv.
Lethal exposure level
A dangerous dose can take a level of 0,75 Sv. With this value, a change occurs in a person’s blood, and although there are no deaths immediately, the probability of cancer in the future is quite high.
As noted above, the organs (liver, lungs, stomach, skin) perceive radiation unevenly. Radiation sickness starts with a dose of 1-2 Sievert and for some this is already a lethal dose. Others will easily endure the infection and recover.
If we proceed from statistics, then the lethal dose will be higher than 7 Sievert or 700 roentgens.
| Dose. Sievert | Effects on humans |
| 1 – 2 Feet | Mild form of radiation sickness. |
| 2 – 3 Feet | Radiation sickness. Mortality during the first month up to 35%. |
| 3 – 6 Feet | Mortality up to 60%. |
| 6 – 10 Feet | Lethal outcome 100% within a year. |
| 10 – 80 Feet | Coma, death in half an hour |
| 80 and more | Immediate death |
Measurement of radiation in the apartment
The radiation level in the room should not exceed 0,25 µSv/h. A room is considered safe if the radon content is not more than 100 Bq per cubic meter. At the same time, in industrial premises it can be up to 300 Bq and 0,6 microSievert.
If the standards are exceeded, then measures are taken to reduce them. If it is impossible to do this, the tenants should be relocated, and the premises should be converted into non-residential or demolished.
The SanPiN indicates the content of thorium, uranium and potassium-40 used in construction for the construction of housing. The total dose from wall and finishing materials should not exceed 370 Bq/kg.
Materials with increased radioactivity
During construction in Soviet times, all materials were tested according to GOST. Therefore, talk about the fact that the “Khrushchev” five-story buildings have radioactivity is nothing more than a myth. The main source of radiation in an apartment or any other room is radon gas.
It belongs to the natural sources of radiation, as it is present in the earth’s crust and is released into the environment, contributing its share to the total radiation background. Penetrating into the room through the foundation and floors, it accumulates, increasing the normal radioactive background. Therefore, do not make the rooms too airtight. An additional source of radon entering the house is water coming from artesian wells and gas.
The main building materials: concrete, brick and wood are not dangerous and are the most harmless. However, in construction and in everyday life, we use materials that emit a fairly large amount of radon. These include:
- pumice;
- granite;
- tuff;
- graphite.
All materials deposited or mined from the earth’s crust can have an increased level of radiation. Therefore, it is good to control it yourself.
How to check for radiation
Checking the level of radiation can occur when buying a new apartment, an apartment in a disadvantaged area, or using suspicious materials in the construction of a house. A person does not have sense organs capable of feeling radiation and assessing the danger. Therefore, to detect it, it is necessary to have specialized devices – dosimeters.
They can be household, professional, industrial or military. Various sensors can be used as a sensitive element: gas discharge, scintillation crystals, mica Geiger-Muller counters, thermoluminescent lamps, pin diodes.
For measurements at home, household dosimeters are available to us. Depending on the device, it can display readings in µSv/h or µR/h. Some devices closer to professional ones can show in both versions. It should be taken into account that household dosimeters have a rather high level of measurement error.