Chemical contamination zone: description, features and interesting facts


In the conditions of active development of new technologies in the field of nuclear physics, one must always be alert. Indeed, on the account of our planet there are more than one sad experience of man-made disasters and chemical accidents. Therefore, it will not be superfluous to learn about the possible consequences of the accident and the order of action in the zone of chemical contamination. Consider this question in more detail.


Basic concepts

A typical variant of a technogenic accident is the penetration of hazardous chemicals into the world around. This is due to damage to the collections of toxic elements and violations of the technological process with their participation, and ends with the contamination of air, soil, water sources, plant and animal world and, of course, people.

Under the zone of chemical contamination is meant the territory (water area), within which there is a spread of toxic chemicals in such concentrations and quantities that pose a threat to human life and health, as well as flora and fauna during a certain period.

Guided by the physical properties and the aggregative state of hazardous substances, it is possible to calculate the scale of infection. In this regard, distinguish primary and secondary clouds. The cloud of poisonous air, formed by the instantaneous release into the atmosphere of the entire mass or part of the tank with OHV at the time of its damage, is called primary. The secondary is a cloud with poisonous evaporation of spilled liquid.

States of poisoned elements

In the zone of chemical contamination, OHV is moved in one of 4 states: from droplet-liquid and vapor to aerosol and gaseous.

The formation of a primary cloud can be promoted by hot OHV vapors released after an explosion or fire has occurred. Then they fall to the ground in droplet form (after cooling and condensation), and the wind can carry condensate rather far from the crash site.


When OHV is emitted into the atmosphere in a droplet or solid form, their droplets (particles) are deposited on the territory. The area of ​​"coverage" and determines the zone of dangerous chemical contamination of the fertile layer of the earth.

Then, after evaporation, the OHV particles rise and concentrate in the near-Earth part of the atmosphere as a derivative cloud.

Under the force of gravitational attraction, solid particles of toxic substances from the aerosol undergo a sedimentation process in the form of dust, and the mass formed after the explosion contains particles of different sizes (within 0.5-300 μm), and the sedimentation rate increases from the particle size. If it is greater than 50 (as is most often the case), then the cloud settles directly near the epicenter of the accident, if it is average (30-50), it can dissipate in the range of one hundred to five hundred meters. The most dangerous for people are small particles of up to 5 microns, since they are characterized by being suspended and penetrating into the depth to the maximum mark of 10 kilometers.

It turns out that 2 territories fall into the zone of chemical contamination: with direct exposure to poisonous substances and with the movement of a radioactive cloud. The most dangerous in an emergency situation is the XOU areas where the toxic substance has emitted into the atmosphere, forming the primary cloud.

The level of concentration of toxic substances

The closer the place of the "eruption" of OHV, the higher their density in the formed cloud. Then there is a gradual decrease in concentration closer to the edges of the zone of chemical contamination. The limits of the latter are subject to variability, the reason for this are air masses with different directions. When the air moves horizontally under the influence of the wind, the infected cloud moves, striking a larger area frontally and in depth. When the wind speeds above 6 m / s, the cloud disperses fairly quickly, and the concentration of toxic substances decreases. Moderate speed, on the contrary, contributes to the preservation of toxic mass above the surface layer of the atmosphere, which increases the scale of the deepening.


Vertical atmospheric stability - types

The first state is called inversion. It is characterized by a lower temperature in the lower layer of air relative to the upper one. This provides a high saturation of OHV in the near-Earth part of the atmosphere and creates a “favorable climate” for the horizontal expansion of the cloud.

In a state of inertness of the atmosphere (isothermy), when the temperature does not differ on both layers of air, the density of hazardous chemicals is not so pronounced.

If the atmosphere is characterized by instability, called convection, is “warmer” in the lower layer of air than in the upper one.

Influence of atmospheric phenomena

Atmospheric precipitation plays its role in the process of OVC fallout: with their help, the liquid and solid components of chemical elements are washed out of the poisonous cloud. The rate of fallout is maximum during rain and rain and is insignificant when there is dry fog, haze or drizzle on the street.


Terrain factor

The scale of the consequences is also influenced by the nature of the territory, which is a zone of possible chemical contamination. If the terrain rises along the “flow” line of the cloud, we can talk about a decrease in the depth of its diffusion. The top of the hill has a low degree of accumulation of hazardous substances. But in deep ravines, with a passing cloud of wind, its movement is active. Perpendicular directionality can cause stagnation of the cloud.

Forest area restricts chemical cloud access. In populated areas, compared to open areas, OHV fumes are usually more concentrated. Hazardous substances have the ability to enter enclosed spaces. “Achilles heel” here are the station buildings, public institutions and commercial premises. The most safe you can feel in residential apartments.

Properties of toxic chemicals

Some of their elements have a high penetrating property, which is fraught with poisoning of all spheres of the environment.

Some OHVs can disrupt the ecological balance by infecting the biosphere for a long period (from a week to a month).

In the case of complete or partial destruction of XPO, provoked by military actions or a natural or man-made emergency, a number of different OHVs can get into the atmosphere. In this case, several types of hazardous elements form a zone of chemical contamination. This allows you to determine the mass of the poisonous cloud, guided by the following parameters: the number, physico-chemical properties and toxicity. The initial part of the zone “accumulates” all the hazardous substances, and in the opposite area there are concentrated substances with a large amount and toxic dose. Do not forget that such a mixed poison cloud can explode and ignite due to the likely chemical reactions between different components.


How to behave in the zone of chemical contamination

If you have heard "chemical alert" or found signs of the presence of toxic substances, you must adhere to the following rules:

  • use personal protective equipment;
  • seek immediate shelter in the nearest shelter or sealed living area;
  • at the entrance to the shelter leave the PPE and outerwear.

Move around the poisoned area should be quickly but calmly so as not to raise dust. Also, you can not lean on the walls of buildings and touch the surrounding objects. On the way you should avoid liquid drops or scattered unknown substances in the form of powder. The path to the shelter must be chosen without ravines, ravines, swamps and tunnels. If there are drops or traces of chemicals on the skin and garments, they should be treated with a tampon soaked in liquid from an individual protection package, in the absence of one, remove them with paper, a rag or a handkerchief.


Since the stay of people in chemically contaminated areas threatens with radiation and radiation sickness, medical prophylaxis of ionizing lesions with anti-radiation drugs is carried out.

Interesting Articles

Far East: development prospects (general description)

Imaginary is ... True and Imaginary Values

Actor Francois Arno: the best films. Biography, personal life, photo

What is the thermohaline circulation of the oceans?