Do you need to worry about cosmic radiation when flying?

Do you need to worry about cosmic radiation when flying?

Not long ago, a special work-related injury case attracted attention. After a Korean Air flight attendant died of stomach cancer, South Korean authorities identified the incident as a cosmic radiation workplace injury for the first time. The Korea Labor and Welfare Corporation revealed that the flight attendant flew an average of 1,022 hours per year from 1995 to 2021. This incident triggered public attention to the radiation problem of air travel.

So, what is cosmic radiation? Does cosmic radiation affect the human body? A reporter from Science and Technology Daily interviewed relevant experts.

 Radiation exposure while traveling is within safe limits

When it comes to radiation, many people’s first reaction is panic. In fact, radiation is just a general concept, with various types and ubiquity.

Liu Libo, a professor at the School of Public Health of Jilin University, said that the main thing talked about in life that may have an impact on the human body is ionizing radiation, including radiation generated by hospital CT examination equipment, X-ray machines, etc. During the flight of an airplane, the radiation that people on board are exposed to is also ionizing radiation.

Bian Yueyue, a senior engineer at the China Geological Museum, said that ionizing radiation can also be subdivided into artificial radiation and natural radiation, with the latter also known as background radiation. Artificial radiation mainly comes from human nuclear technology applications, such as radiation generated by CT examination equipment. Background radiation is radiation that has long existed in nature, mainly derived from cosmic rays and radionuclides in the earth’s crust, and has existed on the earth longer than humans.

Aviation radiation is produced when cosmic rays penetrate the Earth’s atmosphere. These cosmic rays usually have extremely high energy and travel through space at nearly the speed of light. The equatorial regions receive the least amount of cosmic radiation, while the polar regions receive the most.

Due to the obstruction of the earth’s magnetic field and the atmosphere, most cosmic rays have been exhausted by the time they reach the surface, and have minimal impact on the human body. However, the higher the altitude where people are, the more cosmic radiation they are exposed to. Studies have shown that for every 2,000 meters the flight altitude of an airplane increases, the dose of cosmic rays to the human body doubles.

The unit of measure of radiation dose to the human body is usually millisievert (mSv). Bian Yueyue said that for people living in low-altitude areas, radionuclides in the earth’s crust are the main source of background radiation, and they are hidden in soil, rocks, and oceans. The average background radiation in my country is about 3.1mSv.

When an airplane flies in the sky 10,000 meters above the earth, the radiation dose brought by cosmic rays is approximately 0.006mSv per hour. If you take a flight from Beijing to Shanghai, the radiation dose received by passengers during the approximately 2-hour flight is only about 0.012mSV, which is completely within the safe range.

No additional protection is required in daily life

The National Nuclear Safety Administration has formulated the “Basic Standards for Ionizing Radiation Protection and Radiation Source Safety” (hereinafter referred to as the “Standards”) with reference to the relevant recommendations of the International Commission on Radiation Protection. The “Standards” mainly focus on ionizing radiation protection in the field of nuclear science and technology, and are mainly applicable to professionals who will be exposed to ionizing radiation at work. For this group of professionals, the “Standards” stipulate that their average annual effective radiation dose for five consecutive years shall not exceed 20mSv, and the dose in any one year shall not exceed 50mSv.

The Standards do not stipulate safe radiation doses that the general public can accept each year. For specific members of the public, such as those who may be close to ionizing radiation-generating facilities, the Standard states in the appendix that their annual average dose does not exceed 1 mSv. Under special circumstances, if the average annual dose for five consecutive years does not exceed 1mSv, the dose in a single year can be increased to 5mSv.

However, it needs to be clear that the dose limits given in the “Standards” exclude background radiation that humans cannot avoid. In addition, these doses specified in the “Standards” are only to facilitate the effective control of the application and practice of nuclear technology, and are not safe values ​​for judging whether the human body is harmed.

For example, when people undergo X-ray examination, the radiation dose they receive at one time is about 0.2mSv. CT examinations produce more radiation, about 2mSv to 10mSv at a time. Although it seems that they have exceeded the 1mSv management limit stipulated in the “Standards”, it does not mean that the human body will definitely be affected. In addition, due to the need to actively accept iatrogenic radiation, it is not within the scope of the “Standards”. It is generally believed that human health risks will increase significantly only when the annual radiation dose exceeds 100mSv.

Liu Libo said that in daily life, unless there are special circumstances, there is no need for additional radiation protection. If you need to receive hospital-source radiation, you must strictly follow the doctor’s instructions and conduct relevant examinations at the prescribed number of times.

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