Mmhg unit of measure. The impact of atmospheric pressure on human health

About what atmospheric pressure is, we are told at school in the lessons of natural history and geography. We get acquainted with this information and safely throw it out of our heads, rightly believing that we will never be able to use it.

But years later, stress and environmental conditions environment will have an impact on us. And the concept of "geodependence" will no longer seem like nonsense, because pressure surges and headache begin to poison life. At this point, you will have to remember what it is like in Moscow, for example, in order to adapt to new conditions. And live on.

School basics

The atmosphere that surrounds our planet, unfortunately, literally puts pressure on all living and non-living things. To define this phenomenon, there is a term - atmospheric pressure. This is the force of the impact of the air column on the area. In the SI system, we talk about kilograms per 1 square centimeter. Normal atmospheric pressure (for Moscow, optimal indicators have long been known) affects the human body with the same force as a weight weighing 1.033 kg. But most of us don't notice it. Enough gases are dissolved in body fluids to neutralize all unpleasant sensations.

Atmospheric pressure standards in different regions different. But 760 mm Hg is considered ideal. Art. Experiments with mercury were most revealing at a time when scientists were proving that air has weight. Mercury barometers are the most common instruments for measuring pressure. It should also be remembered that the ideal conditions for which the named 760 mm Hg are relevant. Art., is a temperature of 0 ° C and the 45th parallel.

In the international system of units, it is customary to define pressure in Pascals. But for us it is more familiar and understandable to use the fluctuations of the mercury column.

Relief features

Of course, many factors influence the value of atmospheric pressure. The most significant are the relief and proximity to the magnetic poles of the planet. The norm of atmospheric pressure in Moscow is fundamentally different from the indicators of the same St. Petersburg; and for the inhabitants of some remote village in the mountains, this figure may seem completely anomalous. Already at the level of 1 km above sea level It corresponds to 734 mm Hg. Art.

As already noted, in the region of the earth's poles, the amplitude of pressure changes is much higher than in the equatorial zone. Even during the day, atmospheric pressure changes somewhat. Slightly, however, only 1-2 mm. This is due to the difference between day and night temperatures. The nights are usually cooler, which means the pressure is higher.

pressure and man

For a person, in essence, it does not matter what atmospheric pressure is: normal, low and high. These are very arbitrary definitions. People tend to get used to everything and adapt. Much more important is the dynamics and magnitude of changes in atmospheric pressure. There are quite a lot of zones on the territory of the CIS countries, in particular in Russia. Often, local residents do not even know about it.

The norm of atmospheric pressure in Moscow, for example, may well be considered as a non-constant value. After all, every skyscraper is a kind of mountain, and the higher and faster you go up (go down), the more noticeable the drop will be. Some people may well pass out while riding a high-speed elevator.

Adaptation

Doctors almost unanimously agree that the question "what atmospheric pressure is considered normal" (Moscow or any settlement on the planet - it doesn't matter) is incorrect in itself. Our body adapts perfectly to life above or below sea level. And if the pressure does not have a detrimental effect on a person, it can be considered normal for a given area. Doctors say that the norm of atmospheric pressure in Moscow and other large cities is in the range from 750 to 765 mm Hg. pillar.

A completely different matter is the pressure drop. If within a few hours it rises (falls) by 5-6 mm, people begin to experience discomfort and pain. This is especially dangerous for the heart. Its beat becomes more frequent, and a change in the frequency of breaths leads to a change in the rhythm of oxygen supply to the body. The most common ailments in such a situation are weakness, etc.

Meteorological dependence

Normal atmospheric pressure for Moscow may seem like a nightmare to a visitor from the North or from the Urals. After all, each region has its own norm and, accordingly, its own understanding of the stable state of the body. And since in life we do not concentrate on exact pressure indicators, weather forecasters always focus on what kind of pressure it is for a given region - increased or decreased.

After all, not every person can boast that he does not notice the corresponding changes. Anyone who cannot call himself lucky in this matter must systematize his feelings during pressure drops and find acceptable countermeasures. A cup is often enough strong coffee or tea, but sometimes more serious help in the form of medicines is needed.

pressure in the metropolis

The most meteorologically dependent are residents of megacities. It is here that a person experiences more stress, lives life at a high pace and experiences environmental degradation. Therefore, to know what is the norm of atmospheric pressure for Moscow is vital.

The capital of the Russian Federation is located on the Central Russian Upland, which means that there is a priori a zone of low pressure. Why? It's very simple: the higher above sea level, the lower the atmospheric pressure. For example, on the banks of the Moscow River, this figure will be 168 m. And maximum value in the city it was recorded in Teply Stan - 255 m above sea level.

It can be assumed that Muscovites expect abnormally low atmospheric pressure much less frequently than residents of other regions, which, of course, cannot but rejoice them. And yet, what atmospheric pressure is considered the norm in Moscow? Meteorologists say that usually its indicator does not exceed 748 mm Hg. pillar. This means little, because we already know that even a quick rise in an elevator can have a significant effect on a person's heart.

On the other hand, Muscovites do not feel uncomfortable if the pressure fluctuates between 745-755 mm Hg. Art.

Danger

But from the point of view of doctors, not everything is so optimistic for the residents of the metropolis. Many experts rightly believe that working on the upper floors of business centers, people endanger themselves. Indeed, in addition to the fact that they live in a zone of low pressure, they also spend almost a third of the day in places with

If we add to this fact violations of the ventilation system of the building and the constant operation of air conditioners, it becomes obvious that the employees of such offices are the most inefficient, sleepy and sick.

Results

Actually, it is worth remembering a few points. First, there is no single ideal value for normal atmospheric pressure. There are regional regulations that may differ significantly in terms of absolute indicators. Secondly, the characteristics of the human body make it easy to experience pressure drops if this happens rather slowly. Thirdly, the healthier we lead and the more often we manage to observe the daily regimen (getting up at the same time, a long night's sleep, following an elementary diet, etc.), the less we are subject to meteorological dependence. So, more energetic and cheerful.

; sometimes called "torr"(Russian designation - torr, international - Torr) in honor of Evangelista Torricelli.

The origin of this unit is connected with the method of measuring atmospheric pressure using a barometer, in which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturation vapor pressure at room temperature.

Atmospheric pressure at sea level is approximately 760 mm Hg. Art. Standard atmospheric pressure is assumed to be (exactly) 760 mm Hg. Art. , or 101 325 Pa, hence the definition of a millimeter of mercury (101 325/760 Pa). Previously, a slightly different definition was used: the pressure of a column of mercury with a height of 1 mm and a density of 13.5951 10 3 kg / m³ with a free fall acceleration of 9.806 65 m / s². The difference between these two definitions is 0.000014%.

Millimeters of mercury are used, for example, in vacuum technology, meteorological reports and blood pressure measurements. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the natural transition for vacuum workers to microns (microns) is usually also carried out without indicating “pressure of mercury”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the ultimate vacuum created by this pump, measured in microns of mercury. Of course, no one uses the Torricelli pressure gauge to measure such low pressures. To measure low pressures, other instruments are used, for example, a McLeod pressure gauge (vacuum gauge).

Sometimes millimeters of water column are used ( 1 mmHg Art. = 13,5951 mm w.c. Art. ). In the United States and Canada, the unit of measure is "inch of mercury" (symbol - inHg). one inHg = 3,386389 kPa at 0 °C.

Pressure units

	Pascal (Pa, Pa)	Bar (bar, bar)	technical atmosphere (at, at)	physical atmosphere (atm, atm)	millimeter of mercury (mm Hg, mm Hg, Torr, Torr)	Water column meter (m water column, m H 2 O)	Pound-force per sq. inch (psi)
1 Pa	1 / 2	10 −5	10.197 10 −6	9.8692 10 −6	7.5006 10 −3	1.0197 10 −4	145.04 10 −6
1 bar	10 5	1 10 6 dynes / cm 2	1,0197	0,98692	750,06	10,197	14,504
1 at	98066,5	0,980665	1 kgf / cm 2	0,96784	735,56	10	14,223
1 atm	101325	1,01325	1,033	1 atm	760	10,33	14,696
1 mmHg Art.	133,322	1.3332 10 −3	1.3595 10 −3	1.3158 10 −3	1 mmHg Art.	13.595 10 −3	19.337 10 −3
1 m water Art.	9806,65	9.80665 10 −2	0,1	0,096784	73,556	1 m water Art.	1,4223
1psi	6894,76	68.948 10 −3	70.307 10 −3	68.046 10 −3	51,715	0,70307	1lbf/in2

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Notes

An excerpt characterizing a millimeter of mercury

In October 1805, Russian troops occupied the villages and cities of the Archduchy of Austria, and more new regiments came from Russia and, weighing down the inhabitants with billeting, were located near the Braunau fortress. In Braunau was the main apartment of the commander-in-chief Kutuzov.
On October 11, 1805, one of the infantry regiments that had just arrived at Braunau, waiting for the review of the commander-in-chief, stood half a mile from the city. Despite the non-Russian terrain and situation (orchards, stone fences, tiled roofs, mountains visible in the distance), the non-Russian people, who looked at the soldiers with curiosity, the regiment had exactly the same appearance as any Russian regiment preparing for a show somewhere in the middle of Russia.
In the evening, on the last march, an order was received that the commander-in-chief would watch the regiment on the march. Although the words of the order seemed unclear to the regimental commander, and the question arose of how to understand the words of the order: in marching uniform or not? in the council of battalion commanders, it was decided to present the regiment in full dress on the grounds that it is always better to exchange bows than not to bow. And the soldiers, after a thirty-verst march, did not close their eyes, they repaired and cleaned themselves all night; adjutants and company officers counted, expelled; and by morning the regiment, instead of the sprawling disorderly crowd that it had been the day before on the last march, represented a slender mass of 2,000 people, each of whom knew his place, his business, and of whom each button and strap was in its place and shone with cleanliness. . Not only the outside was in good order, but if the commander-in-chief had been pleased to look under the uniforms, then on each he would have seen an equally clean shirt and in each knapsack he would have found a legal number of things, “an awl and a soap,” as the soldiers say. There was only one circumstance about which no one could be calm. It was shoes. More than half of the people had their boots broken. But this shortcoming did not come from the fault of the regimental commander, since, despite repeated demands, the goods from the Austrian department were not released to him, and the regiment traveled a thousand miles.
The regimental commander was an elderly, sanguine general with graying eyebrows and sideburns, thick and broad more from chest to back than from one shoulder to the other. He was wearing a new, brand-new, creased uniform and thick golden epaulettes, which seemed to raise his stout shoulders rather than downwards. The regimental commander looked like a man happily doing one of the most solemn deeds of life. He paced in front of the front and, as he walked, trembled at every step, slightly arching his back. It was evident that the regimental commander was admiring his regiment, happy with them, that all his mental strength was occupied only by the regiment; but, in spite of this, his trembling gait seemed to say that, in addition to military interests, the interests of social life and the female gender also occupy a considerable place in his soul.
“Well, father Mikhailo Mitrich,” he turned to one battalion commander (the battalion commander leaned forward smiling; it was clear that they were happy), “I got nuts this night. However, it seems, nothing, the regiment is not bad ... Eh?

For normal atmospheric pressure, it is customary to take the air pressure at sea level at a latitude of 45 degrees at a temperature of 0 ° C. In these ideal conditions a column of air presses on each area with the same force as a column of mercury 760 mm high. This figure is an indicator of normal atmospheric pressure.

Atmospheric pressure depends on the height of the area above sea level. On a hill, the indicators may differ from ideal, but at the same time they will also be considered the norm.

Atmospheric pressure standards in different regions

As altitude increases, atmospheric pressure decreases. So, at an altitude of five kilometers, the pressure indicators will be approximately two times less than at the bottom.

Due to the location of Moscow on a hill, the pressure here is considered to be 747-748 mm of column. In St. Petersburg, normal pressure is 753-755 mmHg. This difference is explained by the fact that the city on the Neva is located lower than Moscow. In some areas of St. Petersburg, you can meet the ideal pressure rate of 760 mm Hg. For Vladivostok, the normal pressure is 761 mmHg. And in the mountains of Tibet - 413 mm of mercury.

The effect of atmospheric pressure on people

A person gets used to everything. Even if the normal pressure is low compared to the ideal 760 mmHg, but is the norm for the area, people will.

A person's well-being is affected by a sharp fluctuation in atmospheric pressure, i.e. decrease or increase in pressure by at least 1 mmHg for three hours

With a decrease in pressure, there is a lack of oxygen in the human blood, hypoxia of the cells of the body develops, and the heartbeat quickens. Headaches appear. There are difficulties in the respiratory system. Due to poor blood supply, a person may be disturbed by pain in the joints, numbness of the fingers.

An increase in pressure leads to an excess of oxygen in the blood and tissues of the body. The tone of blood vessels increases, which leads to their spasms. As a result, the blood circulation of the body is disturbed. There may be visual disturbances in the form of the appearance of "flies" before the eyes, dizziness, nausea. A sharp increase in pressure to large values \u200b\u200bcan lead to rupture of the ear tympanic membrane.

In which the pressure is balanced by a column of liquid. It is often used as a liquid because it has a very high density (≈13,600 kg/m³) and low saturation vapor pressure at room temperature.

Millimeters of mercury are used, for example, in vacuum technology, meteorological reports and blood pressure measurements. Since in vacuum technology very often pressure is measured simply in millimeters, omitting the words “mercury column”, the natural transition for vacuum workers to microns (microns) is usually also carried out without indicating “pressure of mercury”. Accordingly, when a pressure of 25 microns is indicated on a vacuum pump, we are talking about the ultimate vacuum created by this pump, measured in microns of mercury. Of course, no one uses a Torricelli pressure gauge to measure such low pressures. To measure low pressures, other instruments are used, for example, a McLeod pressure gauge (vacuum gauge).