The impact of air pollution on humans, flora and fauna. OBZhD

BASICS OF SAFE LIFE
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The impact of air pollution on humans, flora and fauna. Basics of safe life

Fundamentals of Safe Life Activities (OBZhD)

All air pollutants to a greater or lesser extent have a negative impact on human health. These substances enter the body mainly through the respiratory system. The respiratory organs suffer directly from pollution, since up to 50% of particles with a radius of 0,01-0,1 microns that enter the lungs are deposited in them.

In the body, particles cause a toxic effect because they: a) are toxic (poisonous) in their chemical or physical nature; b) interfere with one or more of the mechanisms by which the respiratory (respiratory) tract is normally cleared; c) are carriers of a poisonous substance absorbed by the body.

In some cases, exposure to one of the pollutants in combination with others leads to more serious health problems than exposure to either of them alone. The duration of exposure plays an important role.

Statistical analysis made it possible to reliably establish the relationship between the level of air pollution and diseases such as upper respiratory tract damage, heart failure, bronchitis, asthma, pneumonia, emphysema, and eye diseases. A sharp increase in the concentration of impurities, which persists for several days, increases the mortality of the elderly from respiratory and cardiovascular diseases.

In December 1930, in the valley of the river Meuse (Belgium), severe air pollution was noted for 3 days; as a result, hundreds of people fell ill and 60 people died - more than 10 times the average death rate. In January 1931, in the area of Manchester (Great Britain), for 9 days, there was a strong smoke in the air, which caused the death of 592 people. In January 1956, about 1000 Londoners died as a result of prolonged smoke. Most of those who died unexpectedly suffered from bronchitis, emphysema, or cardiovascular disease.

Carbon monoxide (CO). The concentration of this gas, exceeding the maximum allowable, leads to physiological changes in the human body. This is explained by the fact that CO is an extremely aggressive gas that easily combines with hemoglobin. When combined, carboxyhemoglobin is formed, an increase in the content of which in the blood (in excess of the norm equal to 0,4%) is accompanied by:

deterioration in visual acuity and the ability to assess the duration of time intervals;
violation of some psychomotor functions of the brain (at a content of 2-5%);
changes in the activity of the heart and lungs (with a content of more than 5%);
headaches, drowsiness, spasms, respiratory disorders and in some cases death (when the content is more than 10%).

The degree of impact of carbon monoxide on the body depends not only on its concentration, but also on the time spent (exposure) of a person in CO-polluted air. Fortunately, the formation of carboxyhemoglobin in the blood is a reversible process: after the inhalation of CO is stopped, its gradual removal from the blood begins; in a healthy person, the CO content in the blood decreases by 3 times every 4-2 hours.

Carbon monoxide is a very stable substance, its lifetime in the atmosphere is 1-A months. With an annual intake of 350 million tons, the concentration of CO in the atmosphere would have to increase by about 0,03 million tons/year. However, this, fortunately, is not observed, which mankind owes mainly to soil fungi, which very actively decompose CO (the transition of CO into CO2 also plays a positive role).

Sulfur dioxide (SO2) and sulfuric anhydride (SO3). In combination with suspended particles and moisture, they have the most harmful effect on living organisms. SO2 is a colorless and non-flammable gas; in a mixture with solid particles (at a smoke concentration of 150-200 µg/m3) leads to an increase in symptoms of difficulty breathing and exacerbation of lung diseases, and at a smoke concentration of 500-750 µg/m3, the number of patients increases sharply and the number of deaths increases.

Nitrogen oxides and some other substances. Nitrogen oxides (the most toxic nitrogen dioxide - NO2), combining with ultraviolet solar radiation with hydrocarbons (among which olefins are the most reactive), form peroxylacetyl nitrate (PAN) and other photochemical oxidants, including peroxybenzoyl nitrate (PBN), ozone, peroxide hydrogen, nitrogen dioxide. These oxidizing agents are the main constituents of the photochemical smog that often occurs in heavily polluted cities located at low latitudes in the northern and southern hemispheres.

An estimate of the rates of photochemical reactions leading to the formation of PAN, PBN, and ozone shows that in a number of southern cities in the summer around noon (when the influx of ultraviolet radiation is high), these rates exceed the values at which smog begins to form. Thus, in Almaty, Yerevan, Tbilisi, Ashgabat, Baku, Odessa and other cities, with the observed levels of air pollution, the maximum rate of CO formation reached 0,70-0,86 mg/m3 per hour, while smog occurs already at a rate of 0,35 .3 mg/mXNUMX per hour.

The presence of nitrogen dioxide and potassium iodide in PAN gives smog a brown tint. At high concentrations, PAN falls to the ground in the form of a sticky liquid that has a detrimental effect on vegetation.

All oxidizing agents - primarily PAN and PBN - strongly irritate the mucous membrane of the eyes and cause inflammation. In combination with ozone, these substances irritate the nasopharynx, lead to vasospasm, and at high concentrations (over 3-4 mg/m3) they cause severe coughing.

Let's name some other air pollutants that have a harmful effect on humans. It has been established that people who professionally deal with asbestos have an increased likelihood of cancer. Beryllium has harmful effects on the respiratory tract, as well as on the skin and eyes. Mercury vapor disrupts the functioning of the central nervous system and kidneys. Because mercury can accumulate in the body, exposure to mercury eventually leads to mental impairment.

In cities, due to increasing air pollution, the number of patients suffering from chronic bronchitis, emphysema, lung cancer, and various allergic diseases is steadily growing.

Authors: Aizman R.I., Krivoshchekov S.G.

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