What is MPC? Maximum permissible concentration of harmful substances in the air

The maximum permissible concentration of harmful substances is the permissible value of a polluting chemical compound contained in soil, water or air, which does not directly or indirectly affect living organisms. Values ​​in appropriate units are determined by toxicological studies.

MPC characteristic as a meter

What is MPC in environmental regulation? This is the main indicator of industrial ecology, which all manufacturing enterprises are guided by. The MPC values ​​of substances are derived and distributed according to the type of chemical structure and toxicological effect on living organisms. GOSTs have been created, compliance with which is mandatory.

Depending on the environment in which the harmful substances are located, MPC is measured in:

• mg / dm ³ - for measurement in the hydrosphere;
• mg / m ³ - for measurements in the atmosphere and air of the working space;
• mg / kg - to determine the indicator in the soil.

When deriving the MPC value, the detrimental effect not only on humans, but also on all living organisms as a whole, is taken into account. Compliance with established standards allows you to save the entire ecosystem, and not individual species of the animal and plant world.

Classification

MPC of harmful substances, depending on the degree of exposure to living organisms, is divided into 4 hazard groups:

1. Grade I is extremely dangerous.
2. Grade II is very dangerous.
3. Grade III is dangerous.
4. IV class - moderately dangerous.

Depending on the belonging of the pollutant to the danger groups, its MPC and the time spent in the environment of living organisms in the presence of chemical compounds change.

Varieties of MPC

Depending on the criteria for assessing the environment, several MPC values ​​are derived.

For industrial areas, there are:

• PDK.z. - used to assess the sanitary state of the atmosphere of the working area. The work area is the space in which workers are located when completing a task, which includes 2 meters above the site level. The coefficient expresses the amount of pollutant in the air that does not cause any deviations in human health for several decades.
• MPC.p. - It is allocated at industrial enterprises or at a separate site. Usually, the value is 0.3 MPC

For the urban zone, there are other standards for the ecological state of the atmosphere, which is determined by the following factors:

• MPC.p. - the total allowable value of the pollutant in the atmosphere of the village. Separate the coefficients of the average daily and maximum single environmental pollution.
• PDKm.r. - the amount of pollutant in the atmosphere of the urban zone in the maximum expression, which is permissible for single inhalation. The coefficient is calculated so that the substance does not cause a reaction to chemical irritants during short-term exposure (no more than 20 minutes).
• MPC.s. - regulates the amount of harmful substances in a concentration that does not adversely affect human health, provided that it is inhaled around the clock.

It should be understood what is the MPC of working and urban space. PDK.z. calculated on the basis of the following source data:

• in a polluted environment are adults with good health;
• the stay is limited by job description and usually does not exceed 8 hours.

Harmful substances in the atmosphere of the village affect every inhabitant: an adult or a child, sick or healthy, while it is around the clock and continuous throughout life. As a result of this, for the same pollutants can be determined significantly different from each other the values ​​of maximum permissible concentrations. Typically, the MPC coefficient of substances in the air of the working area is much higher than the MPC.p.

Definitions of MPC values ​​in water and soil

What is the MPC of water bodies? This is the established standard for the concentration of pollutant per 1 liter of water. The coefficient values ​​are determined separately for each type of reservoir. Distinguish waters of fishery, drinking and domestic purposes.

Determination of MPC of pollutants in the soil is the most difficult task. The calculation is based on the properties of the soil and the chemical nature of the harmful substances. The indicators are always different, and tabular values ​​for each polluting compound are not displayed.

MPC distribution by nature of exposure

What is the MPC for chemical compounds if each substance can act differently?

For a systematic classification of harmful chemicals, several groups are distinguished according to the characteristic signs of exposure to a living organism, in particular a person:

• general toxic;
• annoying;
• sensitizers;
• carcinogens;
• mutagens;
• affecting reproductive health.

Each of the groups has specific signs of poisoning, validity periods and derived MPC.

General toxic pollutants

Common toxins cause severe poisoning of the body as a whole. The most obvious disorders are noticeable on the part of the human nervous system: convulsions, impaired consciousness, and paralysis occur. Aromatic hydrocarbons and their nitro and amide derivatives, organic compounds with phosphorus, chlorine, and also some inorganic substances belong to the group of substances of common toxins .

The most common of them are:

• arsenic and its compounds;
• benzene, toluene, aniline, xylene;
• dichloroethane;
• Hg;
• Pb;
• carbon monoxide (IV).

Infection with many of the substances occurs not only in production, but also in everyday life.

MPC in atmospheric air of toxic substances

Consider the indicators of the average daily and one-time MPC in the air of the urban and working areas. For convenience and clarity, we submit the information in the form of a table.

The average daily concentration of harmful substances implies interaction with the human body for several years without the development of any consequences.

Irritating chemicals

Chemical compounds affect the skin, mucous membranes and respiratory tract. Most often, halogens and oxides of nitrogen and sulfur act as irritating substances.

Prolonged inhalation of harmful vapors leads to serious respiratory failure, intoxication and death.

Sensitizers and their MPC in the atmosphere

Sensitizing substances cause an allergic reaction in humans. Common compounds of this group include aldehydes and hexachloran.

Sensitizers enter the atmosphere during fuel combustion and production activities. A small amount of formaldehyde is also released at home: it is found in many building and decoration materials, furniture.

Carcinogens and mutagens

The most dangerous group of chemical pollutants, whose effect on the human body has been underestimated for a long time. Carcinogens and mutagens are potent substances with a long latent period of action. Carcinogens include asbestos, beryllium, benzpyrene, aromatic amines. They provoke the formation of various malignant tumors.

Mutagens provoke changes in the human genotype, which are transmitted to offspring. These include radioactive substances, manganese, lead, organic peroxides, formaldehyde.

Many mutagenic substances additionally affect reproductive health, these include: benzene and any derivatives thereof, lead, antimony, manganese, toxic chemicals, chloroprene and others.