Radon: The invisible danger

The article published in the Journal of Science Activities (Ministry of Science and Technology), in June 2006, clearly and fully explains the harmful effects of radioactivity in the air, mainly Alpha rays due to radon radioisotopes. -222 caused.

For a long time, scientists have warned of the risk of lung cancer in community life, in mines, in houses and especially in bedrooms and offices, especially in construction materials.

Radon in the air

Radon emits radioactive rays (Photo: VNN) Radon is a radioactive isotope of natural radioactive chains. Radon-222 of each uranium-238, radon-220 series of thorium-232 and radon-119 chains of uranium-235 chains, commonly known as radon and thoron respectively. Radon and thoron are inert gases, they do not participate in any chemical compound.

Compared to thoron-220 and radon-119, the radioactivity of radon-222 is very high because the half-life of radioactive decay is 3.8 days, while the half-life of thoron is 55 seconds. and of radon-119 is 4 seconds.

Radon is the leading cause of cancer risk in lung carcinogens.

In the air, radon and thoron in the form of free atoms, after escaping from building materials, rock and other minerals, they decay radioactivity into a chain of radioactive isotopes that are dangerous. especially polonium-218.

Polonium alpha decay with a half-life of 3.05 minutes, enough for some breathing cycles in the human respiratory system.

Polonium-218 flies with dust-sized particles of nanometers and micrometres forming radioactive aerosol particles. These radioactive aerosols, which are about a few dozen micrometres in size, can be inhaled through the airways and are more harmful, they can be stored in the alveoli.

At the alveoli, polonium-218 alpha decay emits helium nuclei - alpha particles (with a charge of + 2e; atomic mass is 4).

Very high energy alpha particles will bombard the alveolar cell nucleus, causing chromosomal defects, negatively impacting the cell division mechanism. Part of the nuclear energy dissipates to the nucleus decaying, causing these nuclei to recede. The backward energy of radon nuclei may be sufficient to break down protein molecules in alveolar cells. The result is a very high probability of carcinogenicity due to radon.

Thus, the determination of radioactive aerosol content caused by radon (ie, determination of radon) is very important for the purpose of monitoring and warning of lung cancer risk in community life, in the mines, in houses and specials in bedrooms, offices.

According to the US Environmental Law, the allowable rate of radon in houses is According to the radiation safety standards of the International Atomic Energy Agency (IAEA), the concentration of radon in houses of people must not exceed the range of 200 to 600 Bq / m3 / year, meaning from 0, 6 to 1.7 Bq / m3 / day.

Radon control, warning and mitigation measures

Measurement of radon concentration in the air (Photo: VNN) To determine radon levels, radon measurements are required by specialized equipment. The concentration of radon in the air is displayed in units of pCi / l or Bq / m3.

Places that need to be controlled to alert radon levels are houses, motels, hotels or offices and radioactive ore mining sites.

Radon content in the air depends on the degree of ventilation. Thus, the bedroom or working room with air-conditioning without ventilation is at great risk of radon contamination. The possibility of exposure to radon also depends on the time available at the living space, work or rest.

In particular, radon content depends greatly on materials.

Construction materials of granite origin will give the highest radon content, clay ceramic materials, coal slag bricks are also materials containing many radon. Minerals of sedimentary origin such as ilmenhite, rutile, zircon, monazite rich in radioactivity are also sources of radon.

Hospitals that use Ra-226 needles can also leak or diffuse radon into the air.

To minimize radon content in living and working spaces, it is necessary to use construction materials with low radon. Work and bedroom rooms need to be ventilated. If working in mineral radioactive areas, it is necessary to take into account the working time Radon is everywhere in the world without me . (Photo: VNN) .

Who can assess radon content in the work space?

To determine the activity or radon content, it is necessary to have specialized equipment and the user of the equipment must have a professional qualification and must be authorized by the Department of Radiation and Nuclear Safety and Control

Ho Chi Minh City Nuclear Center (headquartered at 217 Nguyen Trai, District 1, Ho Chi Minh City) is one of the authorized units.

The agency has well-trained radiation safety experts, has a practice certificate, is authorized to advise and evaluate ionizing radiation safety issues, including radon. Besides, other units of Vietnam Atomic Energy Institute such as Da Lat Nuclear Research Institute, Hanoi Nuclear Science and Technology Institute are also authorized units in this field.

(According to Science Activities Review, 6/2006, VietNamNet)