Hazardous substances. The subject of this article is the harmful substances that pollute the atmosphere. They are dangerous for the life of society and for nature as a whole. The problem of minimizing their impact today is truly scary, as it is associated with a real degradation of the human habitat.
The subject of this article is the harmful substances (VV) that pollute the atmosphere. They are dangerous for the life of society and for nature as a whole. The problem of minimizing their impact today is really scary, because it is associated with the real degradation of the environment of people.
Classical sources of explosives are thermal power plants; engines of cars; boiler plants, factories producing cement, mineral fertilizers, various dyes. At present, more than 7 million chemical compounds and substances are produced by humans! Annually the nomenclature of their production increases by about one thousand names.
Not all of them are safe. According to the results of environmental studies, the most polluting emissions of harmful substances into the atmosphere are limited by the nomenclature of 60 chemical compounds.
Briefly about the atmosphere as a macro-region
Let's remind you what the Earth's atmosphere is. (It is logical: we must imagine what this article will tell about pollution).
It should be represented as the uniquely composed air shell of the planet associated with it by gravity. She takes part in the rotation of the Earth.
The boundary of the atmosphere is at the level of one to two thousand kilometers above the earth's surface. The areas above are called the earth's crown.
The main atmospheric components
The composition of the atmosphere is characterized by a mixture of gases. Hazardous substances, as a rule, do not localize in it, distributed in huge expanses. Mostly in the Earth's atmosphere of nitrogen (78%). Next on the part of the specific weight it contains is oxygen (21%), argon is in an order of magnitude smaller (about 0.9%), carbon dioxide occupies 0.3%. Each of these components is important for saving life on Earth. Nitrogen, which is part of proteins, is an oxidation regulator. Oxygen is vital for breathing, while also being a powerful oxidizer. Carbon dioxide enhances the atmosphere, contributing to the greenhouse effect. However, it destroys the ozone layer protected from sunlight by ultraviolet radiation (the maximum density of which is 25 km high).
An important ingredient is also a water vapor. Its highest concentration is in the zones of the equatorial forests (up to 4%), the smallest - in the deserts (0.2%).
General information on atmospheric pollution
Harmful substances are released into the atmosphere as a result of the occurrence of some processes in the nature itself and as a result of anthropogenic activity. Note: modern civilization has transformed the second factor dominating.
The most significant non-systematic natural polluting processes are volcanic eruptions and forest fires. Unlike them, pollen is produced, the products of vital activity of animal populations and so on. Regularly pollute the atmosphere.
Anthropogenic factors of environmental pollution affect their scale and diversity.
Annually, civilization only carbon dioxide sends into the air about 250 million tons. However, it is worth remembering and throttling into the atmosphere products from the combustion of 701 million tons of fuel containing sulfur. Production of nitrogen fertilizers, aniline dyes, celluloid, viscose silk - involves additional air filling with 20.5 million tons of nitrogenous "volatile" compounds.
Significant and dust emissions of harmful substances into the atmosphere, which accompany many types of production. How much dust they throw in the air? a lot:
- the dust entering the atmosphere when burning coal of coal is 95 million tons per year
- drank in the production of cement - 57.6 million tons
- dusts formed during the smelting of pig iron - 21 million tons
- the dust entering the atmosphere when copper smelting is 6.5 million tons.
The problem with modernity was the release of hundreds of millions of car oxides of carbon, as well as compounds of heavy metals. Only for a year in the world produce 25 million new "iron horses"! Chemical harmful substances produced by automobile armies of the metropolises lead to such a phenomenon as could. It generates nitrogen oxides contained in automotive exhaust gases and interacts with hydrocarbons present in the air.
Modern civilization is paradoxical. Due to imperfect technologies, it will inevitably be emitted into the atmosphere by harmful substances. Therefore, at present, the strict legislative minimization of this process becomes of particular urgency. Characteristically, the entire spectrum of pollutants can be classified according to many features. Accordingly, the classification of harmful substances, formed by anthropogenic factor and polluting the atmosphere, involves several criteria.
Classification by aggregate state. Dispersion
BB characterizes a certain aggregate state. Accordingly, they, depending on their nature, can propagate in the atmosphere in the form of gas (steam), liquid or solid particles (disperse systems, aerosols).
The concentration of harmful substances in the air has a maximum value in the so-called disperse systems, characterized by increased permeability of the dusty or fog-shaped state of explosives. Characterize such systems, using classifications based on the dispersion principle for dust and aerosols.
For a dust, the dispersion is determined by five groups:
- particle size not less than 140 μm (very coarse-spread)
- from 40 to 140 microns (coarse-spread)
- from 10 to 40 microns (medium dispersion)
- from 1 to 10 microns (fine disperse)
- less than 1 micron (very fine disperse).
For a liquid, the dispersion qualifies in four categories:
- drops up to 0.5 microns (fog super-thin)
- from 0.5 to 3 microns (fine fog)
- from 3 to 10 microns (foggy coarse dispersion)
- more than 10 microns (spray).
Systematization of explosives on the basis of toxicity
The most frequently mentioned classification of harmful substances by the nature of their effects on the human body. We will tell you a little more about it.
The greatest danger among the whole set of explosives are toxicants, or poisons, which affect proportionately to their amount that has fallen into the human body.
The value of the toxicity of these IVs has a certain numerical value and is determined as a value reciprocal to their average lethal dose for humans.
Its indicator for extremely toxic explosives is up to 15 mg / kg live weight, highly toxic - from 15 to 150 mg / kg; moderately toxic - from 150 to 1,5 g / kg, low toxicity - more than 1,5 g / kg. These are deadly chemicals.
For non-toxic explosives, for example, include inert gases, which are neutral for humans under normal conditions. However, it should be noted that in conditions of high pressure, they narcotically affect the human body.
Classification of toxic ST., By degree of influence
This systematization of ST is based on the legally approved indicator, which determines such concentration, which for a long time does not cause diseases and pathologies not only in the investigated generation, but also in subsequent ones. The name of this standard is the maximum permissible concentration (MPC).
Depending on the values of MPC, four classes of harmful substances are distinguished.
- I grade BB. Extremely dangerous explosives (MPC - up to 0.1 mg / m 3): lead, mercury.
- II class. Highly hazardous explosives (MPC from 0.1 to 1 mg / m 3): chlorine, benzene, manganese, caustic alkalis.
- III class. Moderately dangerous explosives (MPC from 1.1 to 10 mg / m 3): acetone, sulfur dioxide, dichloroethane.
- IV class IV. Low-hazard explosives (MAC - more than 10 mg / m 3): ethyl alcohol, ammonia, gasoline.
Examples of harmful substances of different classes
Lead and its compounds are considered poisonous. This group is the most dangerous chemicals. Therefore lead is attributed to the first class of BB. Maximum allowable concentration is negligible - 0,0003 mg / m 3. The striking effect is expressed in paralysis, effects on the intellect, physical activity, hearing. Lead causes cancer, as well as affects heredity.
Ammonia, or hydrogen nitride, refers to the second class on the criterion of danger. Its MPC - 0.004 mg / m 3. It is a colorless caustic gas, which is lighter than air about twice. Striking in the first place are eyes and mucous membranes. Causes burns, breathlessness.
To save the affected, additional safety measures should be taken: the mixture of ammonia with air is explosive.
Sulfur anhydride is classified as a third grade hazard criterion. His MPCaTM. is 0.05 mg / m 3 and the PDCr. with. - 0.5 mg / m 3.
It is formed when combustion of so-called reserve types of fuel: coal, fuel oil, low-grade gas.
In small doses there is a cough, chest pain. Poisoning of moderate severity is characterized by headache and dizziness. Severe poisoning is characterized by toxic stifling bronchitis, blood damage, dental tissue, and blood. Especially sensitive to sulfur dioxide an asthma.
Chondrogen gas (carbon monoxide) is classified in the fourth grade of BB. His PDKatm. - 0.05 mg / m 3 and PDCr. with. - 0.15 mg / m3. He has neither smell nor color. Acute poisoning is characterized by palpitations, weakness, shortness of breath, dizziness. The average degree of poisoning is characterized by spasm of vessels, loss of consciousness. Severe - violations of breathing and blood circulation, a coma.
The main source of carbon monoxide - an exhaust gas vehicle. Particularly intensively, it is allocated by a transport vehicle, where, due to low-quality MOT, the temperature of gasoline combustion in the engine is insufficient, or when an irregular supply of air to the engine.
Method of protection of the atmosphere: compliance with the limit values
The bodies of the sanitary and epidemiological service are constantly monitored, the level of harmful substances at a level below their maximum permissible concentration is observed.
With the help of regular measurements during the year, the actual concentration of explosives in the atmosphere by the special formula generates an index of average annual concentration (IAA). It also reflects the effects of harmful substances on human health. This index reflects the long-term concentration of harmful substances in the air by the following formula:
In = Σ = Σ (xi / MPC i) Ci
where Xi is the mean annual concentration of CT
Ci - coefficient taking into account the correlation of the MAC of the i-th substance andMAC of sulfur dioxide
The value of IAA less than 5 corresponds to a weak level of pollution, 5-8 defines the average level, 8-13 - high level, more than 13 means significant air pollution.
Types of boundary concentrations
Thus, the permissible concentration of harmful substances in the air (as well as in the waters on the ground, although this aspect is not the subject of this article) is determined in environmental laboratories in the atmospheric air for the absolute majority of the explosives by comparing the actual indicators with the established and regulated obstetomfernymi PDKatm .
In addition, for such measurements directly in settlements, there are complex criteria for determining the concentrations - OBUV (estimated safe levels of exposure), calculated as the actual average weighted amount of PDKatm. right after two hundred BB.
However, this is not all. As you know, any pollution of the atmosphere is easier to prevent than eliminate. Perhaps this is why the maximum permissible concentrations of harmful substances in the largest volumes are measured by ecologists directly in the production sphere, which is precisely the most intense donor of explosives in the environment.
For such measurements, individual indicators of the limiting concentrations of explosives have been set, which exceeds the numerical values considered by us above the PDKatm. and these concentrations are determined on areas directly constrained by production funds. Just for the standardization of this process, the concept of the so-called working zone has been introduced (GOST 12.1.005-88).
What is a work area?
The work area is called a workplace where the production worker constantly or temporarily performs scheduled tasks. By default, the specified space around it is limited to a height of two meters. The same work place (RM) assumes the availability of various production equipment (both main and auxiliary), organizational and technological equipment, necessary furniture. In most cases, the harmful substances in the air appear primarily in the workplace.
If a worker in the RM has about 50% of his working time or is working there for at least 2 hours continuously, then such a RM is called permanent. Depending on the nature of the production itself, the production process can take place in territorially changing working areas. In this case, the employee is not assigned a job, and only the place of permanent appearance is shown - a room where the account of his arrival and departure to work is carried out.
As a rule, environmentalists first measure the concentration of harmful substances on permanent RM, and then - in the areas of staffing.
Concentration of explosives in the working area. Regulations
For work areas, the regulatory value of the concentration of harmful substances is determined, which is defined as safe for the worker's life and health during his full work experience, provided that he is there for 8 hours a day and within 41 hours per week.
Note also that the limiting concentration of harmful substances in the working area significantly exceeds the MPC for the air of settlements. The reason is obvious: the person is in the workplace only during the change.
GOST 12.1.005-88 SSBT normalized allowable quantities of explosives in working areas based on the class of hazard of premises and aggregate state are located there VV. Let's imagine, in tabular form, some information from the above-mentioned GOST:
Table 1. The ratio of MPC for the atmosphere and for the working area
The class is its dangers
In defining hazardous substances in the working area, ecologists use the regulatory framework:
- GN (hygienic norms) 126.96.36.1996-96 "MAC of airborne pressures in the air".
- SanPiN (sanitary and epidemiological rules and regulations) 188.8.131.528-96 "Requirements for hygiene for the microclimate of industrial premises".
Mechanism of infectious air pollution
Harmful chemicals released into the atmosphere form a zone of chemical contamination. The latter is characterized by the depth of the spread of air contaminated with explosives. The windy weather promotes its rapid dissipation. Increasing the air temperature increases the concentration of airborne particles.
The distribution of harmful substances in the atmosphere is influenced by atmospheric phenomena: inversion, isotherm, convection.
The concept of inversion explains familiar to all the phrase: "The warmer the air, the higher it is." Because of this phenomenon, the scattering of air masses is reduced, and high concentrations of explosives persist longer.
The notion of isotherm is associated with the cloudy weather. Favorable conditions for her usually occur in the morning and evening. They do not amplify, but do not weaken the proliferation of BB.
Convection, t. E. Upward air streams, dissipate the zone of infection of BB.
The very zone of infection is divided into areas of lethal concentration and is characterized by concentrations less harmful to health.
Rules for assistance to people affected by infectious diseases
Influence of harmful substances can lead to disruption of people's health and even to the fatal outcome. At the same time, timely assistance can save them life and minimize health damage. In particular, the following scheme allows the well-being of the production personnel in the work areas to determine the fact of the defeat of BB:
Diagram 1. Symptoms of lesions of BB
What should and should not be done in case of acute poisoning?
- The victim is put on a gas mask and evacuated from the zone of injury in any available way.
- In case if the clothes are affected by wet, it is removed, the affected areas of skin are washed with water, the clothes are replaced dry.
- In case of uneven breathing, the victim should be given the opportunity to breathe oxygen.
- Exercise artificial respiration with pulmonary edema is prohibited!
- If affected skin, it should be washed, closed with a gauze bandage and go to the medical institution.
- When the VV hits the throat, the nose, their eyes are washed with 2% solution of baking soda.
Instead of concluding. Improvement of the working area
Recovery of the atmosphere finds its concrete expression in the indicators, if the actual indicators of concentrations of harmful substances in the atmosphere is significantly lower than PDKatm. (mg / m 3), and the parameters of the microclimate of the production premises do not exceed Gdkr. (mg / m 3).
Ending the presentation of the material, we will focus on the problem of healing the working areas themselves. The reason is clear. After all, it is the production that infects the environment. It is therefore advisable to minimize the pollution from its source.
For such healing, new, more environmentally friendly technologies, which exclude emissions of harmful substances into the working zone (and, accordingly, into the atmosphere), are of paramount importance.
What measures are being taken for this? The translation of both furnaces and other thermal installations for the use as a fuel of gas is much less polluting the air of explosives. An important role is played by the reliable sealing of production equipment and storage facilities (storage tanks) for storing BB.
Industrial premises are equipped with exhaust universal ventilation, for the improvement of the microclimate with the help of directional fans, the air movement is created. An effective ventilation system is considered when it provides the current level of harmful substances at the level not more than one third of their standard PDKr.z.
It is technically advisable, as a result of the relevant scientific developments, to radically replace the harmful toxic substances in the working zone with non-toxic ones.
Sometimes (in the presence of dry crushed explosives in air RH) a good result on the healing of air is achieved by its moisture.
We also remind you that working areas should also be protected from the closest sources of radiation, which uses special materials and screens.