Background concentration. Maximum allowable concentration of harmful substances

2024 Author: Henry Conors | [email protected]. Last modified: 2024-02-12 02:48

Anthropogenic pollution of air and other terrestrial environments is one of the pressing problems of mankind. It is growing along with the growth of the world population, the increase in consumer demands of people. Because of this, it becomes more and more difficult to deal with pollution every year. Pollution affects the global climate, the he alth of humans and other living beings, the size of fish stocks, the intensity of photosynthesis, and so on. This influence is mostly negative.

The concept of MPC of harmful substances

In order to somehow normalize the concentration of harmful substances, the concept of the maximum permissible concentration of pollutants was developed and began to be applied. For example, the MPC for carbon dioxide in the atmosphere is set at 350 ppm (now 410 ppm), and indoors - about 600 ppm. Carbon dioxide is the most common, but also the least dangerous of all pollutants. It is mainly dangerous because of its impact on the climate, but in this case it is the least harmful of all long-lived greenhouse gases. The problem is that it is emitted in large quantities, and therefore its impact on the climate and human he alth is greater than that of all other pollutants combined.

What is MPC?

MAC is the maximum level of permissible concentration of a particular substance, in the presence of which, even for a long time, there will be no statistically significant undesirable consequences for nature or humans. However, for each organism MPC may be different. For example, the MPC of sulfur dioxide for humans is 10 times higher than for plants. Therefore, for each specific case, a different parameter is set. The MPC of harmful substances in the air of the working area is always higher than in the air of residential premises.

Differences in MPC

MAC values for the same substance can vary from country to country and from environment to environment. For example, the MPC of lead in water is 0.1 mg/l, the MPC of a harmful substance in the air of the working area is 0.001 mg/m³, and in the atmospheric air it is 0.0003 mg/ m^{3. Over time, MPC values are gradually refined and even revised.}

How is the maximum permissible concentration determined?

When calculating MPC, the results of experiments, numericalcalculations, as well as statistical data. The best option is a combination of all these methods. Computer modeling methods, biotests and theoretical predictions for new substances are now increasingly being used. The reason for the tightening of MPC standards may be occupational diseases of workers who for a long time inhaled air with a previously established MPC value. This was the case, for example, with the MPC for coal dust in the USA.

Law on MPC

The maximum permissible concentration of harmful substances is a hygienic standard, which must be observed without fail. This applies to those organizations that are a source of pollution of the atmosphere and other environments. Data on the permissible concentration of harmful substances are included in sanitary standards, GOSTs and other documents that are mandatory for execution within a given state (in our case, Russia).

MPCs are taken into account when designing new industrial facilities, treatment equipment, filters, etc. Control over compliance with the MPC law is carried out by the Sanitary and Epidemiological Service and environmental organizations. As for the quality of water in the reservoirs of the fishery, the control over their condition is carried out by the Fish Supervision authorities.

Degree of danger of the substance

The lower the maximum allowable concentration of a substance, the higher the degree of its danger. For example, for the most hazardous substances (hydrogen sulfide, mercury, arsenic, etc.), MPC is less than 0.1 mg/m3. For the least hazardous compounds (eg ammonia) the maximum allowable concentration is above 10 mg/m³. At hydrogen fluorideMPC is 0.05 mg/m³, for carbon monoxide – 20 mg/m³, for nitrogen dioxide – 2 mg/m 3^{, while sulfur dioxide has 10 mg/m}3^.

Among the most common elements in nature, zinc, mercury and copper are the most undesirable in drinking water.

Disadvantages of MPC concept

Even if the maximum permissible concentration of all pollutants is below the MPC level, this is not yet a guarantee that the air is absolutely safe for he alth. The reason is that there are usually several pollutants, which means that the sum of their impacts will be greater than that of one single pollutant. Some of the pollutants, when combined, will cause more harm than the simple arithmetic sum of the effects of each of the substances separately. Therefore, Western countries are developing new approaches to assessing the quality of air and other living environments.

Background concentration of pollutants

This is the amount of a harmful substance that is contained in a unit volume of the environment subjected to pollution. Different environments have different definitions of this term:

• Background concentration of substances in the atmosphere (or in water) is the concentration of a substance that is created by all sources of pollution. The exception is the researched.
• Background concentration in water or air is the natural concentration of certain substances that are monitored. Anthropogenic emissions and pollutants from neighboring regions are not included here.included.
• The background concentration of a substance in the soil is the content of pollutants in the soil layer, which is determined in places that are not experiencing anthropogenic impact, or if this impact is minimal.

Methods of interpretation

The concept of background concentration is interpreted in different ways. In accordance with the first option, this is the concentration of pollutants that was measured in areas outside the areas where economic activities are carried out. For clarification, the range of variation in pollution levels in natural areas is determined. At the same time, the amount of background pollution should be determined under conditions that are as similar as possible to the conditions of the area where the level of anthropogenic pollution will be checked.

According to another interpretation, the background concentration is the concentration that was observed in a given place before the emergence of new (researched) sources of pollution.

That is, two rather different interpretations are obtained. Therefore, the calculation of background concentrations of pollutants can be carried out in different ways. Next, consider the main causes of air pollution.

Main sources of air pollution

All sources of pollution are divided into natural and anthropogenic. Natural sources include volcanic eruptions, dust raised from the surface of deserts and savannahs, methane released from swamps, forest and peat fires, and so on.

However, the most common problems withair pollution are anthropogenic. The main sources of air pollution include transport, energy, industry, agriculture, household waste dumps, man-made accidents, smoking, construction, mining, domestic and communal activities, wars, holidays, etc. Let's consider each of them separately:

• Transport is considered the most serious source of air pollution. It accounts for 17% of the total amount of harmful emissions into the atmosphere produced by man. Another disadvantage is that the exhaust pipes of cars are practically at our nose. During the operation of the car, different types of pollutants are formed: soot, dust, hydrocarbons, oxides of sulfur, nitrogen, carbon monoxide, heavy metals. One of the harmful components of transport emissions is benzene. Under unfavorable conditions, benzpyrene can be formed, which is considered a strong carcinogen. Efforts are being made around the world to reduce transport emissions. More and more people in developed countries are now opting for electric cars or bicycles, or using public transport.
• Energy is especially dangerous because of its impact on the climate. Directly on our he alth, it does not affect so much. The fact is that emissions in this case are removed from the place where a person lives. During the operation of coal-fired power plants, in addition to CO_{2, compounds of sulfur, nitrogen, carbon monoxide, soot, ash, radioactive elements (in small quantities), etc. are emitted. smaller. Therefore they are morepreferred for environmental conservation. Nuclear power plants can release large amounts of radionuclides in case of accidents, but they do not pose any danger to the climate.}
• Industry emits a variety of chemical components, as well as dust, soot, ash. The level of emission hazard varies greatly from enterprise to enterprise. Many factories are located in cities and have an impact on human he alth.
• Agriculture is an important source of methane, nitrous oxide, dust and fumes, as well as all compounds that are associated with the operation of harvesting equipment. Cows are recognized as the most dangerous agricultural source of air pollution.
• Dumps of solid domestic, industrial and construction waste emit organochlorine compounds, dust, soot, asbestos and many other harmful substances. They are an important source of methane emissions into the atmosphere. With proper disposal of household waste, the effect of pollution can be minimized.
• In case of man-made accidents, hydrocarbons, ammonia, chlorine, soot, and sulfur compounds can be released into the atmosphere. In fires, the nature of emissions directly depends on what is burning. The most harmful in this case is the burning of plastic based on polyvinyl chloride.
• When smoking, various harmful compounds are released into the atmosphere, including heavy metals, radioactive elements, carcinogens, as well as carbon monoxide, soot. While these emissions are small, the he alth risks associated with smoking can be significant, as many people prefer to smoke indoors, leading toaccumulation of pollutants.
• Construction emits dust, organic compounds, pungent odors, etc. Inhaling these can cause headaches. The most dangerous type of dust that can be generated during construction work is asbestos dust.
• Dust is released during mining, which can contain harmful, and even radioactive, elements.
• Household and municipal activities lead to emissions from fuel combustion, sprayers, dusty materials, etc.
• During wars and holidays, dust and smoke are released, which are associated with the burning of gunpowder in firecrackers and ammunition, as well as with the operation of military equipment.