Radiation fears have increased since the Fukushima nuclear disaster, but not many people understand the real risks and exposure standards. In this article, we’ll explain how radiation works, how it’s measured, and the safety of everyday exposure levels, so you can overcome your fears and make informed decisions.
Since the explosion at the Fukushima nuclear power plant on September 11, 2011, the fear of radiation has increased in South Korea. Radiation carries great risks, such as genetic malformations and cancer, and it is also invisible. As a result, radiation has become a constant source of anxiety in our lives. However, while we’ve all heard of radiation, many of us don’t really understand why it’s harmful and how much radiation we need to be exposed to cause the damage we often imagine. It would be foolish not to do something just because the internet or media says it’s harmful. It would be wise to learn what radiation is, how it is measured, and how much damage it can do to us.
In fact, the study and understanding of radiation advanced rapidly in the late 19th and early 20th centuries. The existence of radiation was first recognized in 1895 when German physicist Wilhelm Röntgen discovered X-rays, followed by French physicist Henri Becquerel’s discovery of natural radiation from uranium in 1896. The discovery of the radioactive substances radium and polonium by Marie and Pierre Curie expanded research into the dangers and benefits of radiation. These discoveries led to the medical use of radiation, for example, radiation therapy to treat cancer, but they also raised awareness of the dangers of radiation.
Imagine you’re traveling to Japan, and you’re wondering how much radiation you’re getting. There is a way to measure how much radiation you’re getting. It’s called a radiation meter. There are several different types of radiation meters, but let’s take a look at how the most common one, the GM tube method, works.
Gases are made up of molecules, and molecules are made up of atoms. And atoms are composed of a nucleus and a number of electrons. When these gas molecules are bombarded with high-energy electromagnetic waves, such as gamma rays, the electrons are knocked out. This separation of electrons is called ionization, which leads to the formation of positive and negative ions. GM tubes utilize this principle.
GM tubes create a voltage inside the tube by placing electrodes inside the gas-filled tube and connecting wires to the outside. When radiation passes through the GM tube, the electrons in the gas are separated by the radiation and ions are generated, and a current flows due to the voltage and ions inside the tube. By measuring this current, the amount of radiation can be measured. This method has become so popular that it is used for monitoring around nuclear facilities.
The radiation that can be measured using these GM tubes is gamma radiation, as shown above. There are three types of radiation: alpha, beta, and gamma rays, of which alpha rays can be blocked by our skin, and beta rays are not very penetrating, so they don’t harm us unless we actually take them. But gamma rays are different. Gamma radiation is what we usually think of as damaging radiation.
Light is called visible light, which is a type of electromagnetic wave, and gamma radiation is also a type of electromagnetic wave. But why does gamma radiation have such a frightening effect on us when light doesn’t do much damage? It’s because its wavelength is much shorter than that of light. The wavelength of electromagnetic waves and the energy of light are inversely proportional. Visible light has a wavelength of about 380 nm to 770 nm, while gamma rays have a wavelength of about 0.01 nm, so their energy is more than 10,000 times different.
Have you ever wondered why light can pass through glass but not through your body? The reason is that light has enough energy to pass through glass, but not enough energy to pass through your body. Gamma rays, however, have enough energy to pass through the human body and can destroy the genetic material and key proteins of cells in their path, causing them to die. The body’s cells are constantly replacing old cells with new ones, and when radiation kills these new cells, they are unable to replace the original ones, causing symptoms (hair loss, partial erythema, blisters, ulcers, necrosis, etc.) to appear some time after exposure. If this destruction is done to germ cells, the chromosomes of the germ cells are altered and the genes of the resulting gametes are also altered, resulting in mutations in the next generation of children.
So how much radiation do we need to receive to be safe? There are many different units to measure radiation, but the international standard is the sievert (Sv), which describes the biological effects of radiation without regard to the form of radioactivity. This unit expresses the energy of the radiation received per mass (J/Kg). To get a sense of how big Sv is, let’s use the radiation we receive in our daily lives as an example: the radiation dose we receive when we take a chest X-ray is 0.1 mSv (0.0001 Sv). The annual radiation exposure limit set by Korean law is 1 msV or less, and symptoms are rarely seen below 200 mSv.
You can check real-time radiation levels on various sites, but for example, the current radiation level in Tokyo, Japan is about 60 nSv/h, which is very low, so traveling to Japan is not a health risk.
If we were to travel to an area where radiation levels could be higher, such as near a nuclear power plant, we might pass up the opportunity due to vague fears. However, nowadays, radiation detectors are widely available, and the radiation levels of seafood imported from Japanese waters are well established due to the concerns of many people. Instead of being afraid of radiation, if you can measure it, do it, and if it’s not too harmful to your health, don’t avoid places that are rumored to be dangerous.
