Metro hazards radiation hazards lead to public concern Experts recommend strict management

Recently, Shenzhen, Shanghai, Beijing and other metro stations X-ray security devices have been exposed by the media without a radiation safety license, causing widespread public panic.

Many X-ray security devices at the entrance of the domestic subway station are familiar with passengers riding the subway. Every package inspection has become a common sense that everyone remembers when they take the subway daily. Recently, Shenzhen, Shanghai, Beijing and other cities in subway stations X-ray security devices have been exposed by the media did not handle the radiation safety license, causing widespread public panic, then the subway security instrument on the human body has any harm? What is its working principle? How much radiation dose does it release? What kind of radiation will we encounter in life? How should we scientifically prevent radiation hazards?

The annual amount of radiation is equivalent to the amount of radiation that took 2 hours by plane. With Metrovision Technology Co., Ltd. supplying metro security instruments in many cities in China, according to the company’s R&D personnel, X-rays are shorter than visible light wavelengths. This kind of electromagnetic radiation has stronger solid and liquid penetrating ability than visible light and can even penetrate a certain thickness of steel plate. When X-rays pass through an article, the internal structures of articles with different material compositions, different densities, and different thicknesses can absorb X-rays to varying degrees. The greater the density and thickness, the more absorption rays; the smaller the density and thickness, the less absorption rays. Therefore, the intensity of the ray transmitted from the article can reflect the internal structure of the article.

Subway X-ray security instrument is a line scan work method, the article is X-ray irradiation layer by layer; transmission ray signal is detected, processed, the obtained data for image reconstruction to get the image, the image can represent the internal information of the item. According to the subway security inspection twice a day for 365 days a year, the radiation dose received by subway passengers every year due to subway security inspection is not more than 0.01mSv (10μSv). This value is equivalent to only 1.5 days of natural background radiation dose or flight 2 Hours of radiation dose, therefore, will not cause harm to passengers.

According to the company, the company’s products received a radiation safety license issued by the Beijing Municipal Environmental Protection Bureau, which was confirmed at the Beijing Environmental Protection Bureau. According to a recent expert who had independently participated in radiation testing at a number of subway stations in Beijing, testing according to the existing standards showed that the radiation doses detected by a number of subway stations in Beijing complied with international and domestic standards.

As for the questioning of the subway security instrument radiation, experts suggested that relevant departments should strengthen the management of the radiation device and strictly handle it in accordance with national standards to eliminate the public’s fear of radiation and avoid “discrimination”.

Everywhere in life there is radiation. "When it comes to radiation, it can be divided into ionizing radiation and non-ionizing radiation." Professor Zhu Li of the Department of Engineering Physics at Tsinghua University introduced that the electromagnetic radiation generated by television towers and microwave ovens belongs to non-ionizing radiation. Nuclear radiation is ionizing radiation, and ionizing radiation includes α, β, γ rays, X-rays, neutrons, and other particle beams. "Since ancient times, humans have been thriving in the natural radiation environment. Everyone is not exposed to natural radiation at all times."

There are three sources of natural radiation. One of the sources is the internal radioactive potassium--40. The second source of natural radiation is natural radionuclides such as uranium, plutonium, potassium-40 contained in soil and rocks. Houses, roads, drinking water, foods eaten, and breathing air all contain traces of natural radionuclides. The third source of natural radionuclides is cosmic rays. Cosmic rays include primary cosmic rays from outer space, and secondary cosmic rays from interactions with atmospheric matter. People living on Earth are exposed to such cosmic rays. These three types of natural radiation constitute what people commonly call "natural background radiation."

Natural radiation changes little with time, but varies greatly with area and environment, such as areas with high latitudes, places with high topography, or people in caves, in basements, or living in granite and cinderblock houses. The natural radiation is higher. According to statistics published by the world's authoritative agencies in 2003. The natural radiation level in the world ranges from 1 to 10 millisieverts/year, with an average of 2.4 millisieverts/year, of which 40% in vitro is irradiated in vitro and 60% is in vivo after ingestion and inhalation. .

Zhu Li introduced that people in modern society will also be exposed to a variety of artificial radiation, such as X-rays, watching television, flying, smoking, using a microwave oven. Living around a nuclear power plant receives about 0.0002 mV per year, about 0.005 mV per hour for an airplane, about 0.001 mV per year for a one-hour TV, about 0.02 mV per year for food, and about an X-ray inspection for about a year. 0.50-2.0 mSpv.

There are two major categories of radiation biological effects: somatic effects and genetic effects. Somatic effects are effects on the exposed body itself, such as skin burns, leukemia, thyroid cancer, and death. Genetic effects are caused by mutations in human genetics that affect the health of the next generation. In general, the human body is not damaged by irradiation of 250 millisieverts at a time. "Although the human body has a certain degree of adaptability and resilience to radiation, radiation will damage human health in varying degrees." Zhu Li stressed.

Scientific radiation protection tips Five kinds of people must pay special attention to electromagnetic radiation pollution and life in the high-voltage lines, substations, radio stations, television stations, radar stations, electromagnetic waves near the tower; frequent use of computers, television electronic equipment, medical equipment, office automation Equipment personnel; workers living in the modern electrical automation environment; patients wearing pacemakers; pregnant women, children, the elderly, and sick patients living in these environments.

Placement of household appliances should not be too concentrated on some home appliances that are prone to produce electromagnetic waves, such as radios, televisions, computers, refrigerators, etc. They should not be placed in the bedroom concentrically, lest they expose themselves to the danger of overdose radiation.

Various household appliances, office equipment, mobile phones, etc. should try to avoid long-time operation, and try to avoid the simultaneous release of electromagnetic radiation emitted by a variety of office and household appliances at the same time to enable mobile phone connection. When using, should try to make the head and mobile phone The distance to the antenna is a little longer. It is best to use a separate headset and microphone to answer the phone. Pay attention to the distance between the human body and the office and household appliances. The use of various electrical appliances should maintain a certain safety distance. The farther away from the appliance, the less the electromagnetic wave is infringed upon. For example, the distance between a color TV and a person should be 4 to 5 meters, and the distance from a fluorescent tube should be 2 to 3 meters. After the microwave oven is turned on, it should be at least 1 meter away. Pregnant women and children should be far away from the microwave oven.