Air volume for good health. About real air exchange in a cottage
Only with very strong physical exertion are we able to increase inhaled (exhaled) volume of air four times (that is, up to 2/3 of three liters), thus, two-thirds of the usual lung volume is obtained (2 l - lung capacity- ZHEL). In the same way, with a strong exhalation, a person can exhale an additional 1.5 liters by half a liter - reserve volume. The maximum volume or total lung capacity may exceed 3 liters. For some, it reaches 5 liters or more (for example, trained athletes, athletes, etc.).
Minute and daily volume, taking into account different physical conditions of the body
On average, lying in complete rest, people inhale and exhale every minute 5 liters of air (0.3 m3 / h); when standing - 7 liters, while walking - 10 liters, during simple work - 25, with heavy loads - 40 liters, and at the highest voltage, for example, during sports competitions - 60 liters or more (3.6 m3 / h ). For reference, in one m3 - 1000 liters.So how much air does a person inhale and exhale per day? On average, we pass through our lungs 15 - 20 cubic meters of air per day, and about 6,000 cubic meters per year. meters. In the longest life, a person is not able to use the inhaled air with a volume of even half a cubic kilometer.
Respiratory rate of children and adults
Usually, the respiratory rate in a formed organism is 12 times per minute, in a child it is twice as high.Table 1. Dependence of respiratory rate, tidal volume (absolute and per 1 kg of body weight) on age according to N. A. Shalkov.
6 – 60 liters per minute
To determine how much air a person consumes, the concept of pulmonary ventilation is used. It determines how much air passes through the lungs in one minute. This value is influenced by a number of factors:
- Physical exercise
- Body condition
- The presence of diseases
Since a person is in a state of calm and in motion during the day, the amount of air he needs will be different every day. There are average indicators according to which pulmonary ventilation:
- With calmness, the absence of any stress and physical exertion, it will be 6 liters per minute.
- If you change the state, the result will also change. With light physical effort, a small load (walking, squats) - 20.
- In the case when you do more difficult work (exercises with weight, digging up the earth, chopping wood), the result will increase and will be about 60 liters per minute.
Air exchange in rooms
When designing ventilation systems, a number of recommendations are used. So, the average lung volume in an adult is 4.5 liters (0.0045 m3). One breath is taken per second. Based on these data, the researchers deduced the rate of fresh air consumption. For an adult, this is 30 m3 per hour, and twenty is enough for a child.
The regulatory documents state that 3 m3 of air is needed per square meter of living space. This is an average figure, because no one can say in advance how many people will be in a particular room at the same time.
It should also be noted that in addition to supplying fresh air, there should also be a system for removing carbon dioxide. It is not the same for different rooms. So, in the kitchen, it should be carried out more often. Such a process is measured by the multiplicity. So in the kitchen it is equal to three, and in living quarters - 0.5-1. Also, there are tables of norms, which indicate that the norm of air consumption in cinemas where smoking is prohibited should be 40 m3 per person, and in cafes and restaurants where smoking is allowed - 60 cubic meters.
The main component that we extract from the air is oxygen.
- during sleep, a person needs 15-20;
- if you just lie down - 20 - 25;
- for walking - 30-40 l;
- when running 120-150 liters.
Compared to other organisms, it is the growing and the body of a person who works a lot physically that require a much larger amount of oxygen. Interesting statistics: in one hour a person consumes 15-20 liters of oxygen; during wakefulness, but when a person just lies, the amount of oxygen absorbed increases by 30-35%; a calmly walking person consumes 100% more oxygen; calm and easy work leads to an increase in oxygen absorption by a person by 200%; heavy physical work requires a significant increase in absorbed oxygen - from 600% or more (depending on the intensity of work).
Human lung capacity
The capacity is significantly influenced by the activity of its respiratory processes. The lung capacity of athletes exceeds the norm by 1-1.5 liters, and the lung capacity of professional swimmers can reach 6 liters. Accordingly, an increase in lung capacity decreases the respiratory rate and increases the depth of inhalation.In an ordinary person (non-athlete), the respiratory rate is 14-18 breaths, while in an athlete it is 6-10 breaths per minute. During one complete cycle of breathing, a person inhales 400-600 cubic centimeters of air, while, accordingly, he absorbs 16-24 centimeters of cubic oxygen and releases 14-21 centimeters of cubic carbon dioxide.
A worker who is engaged in heavy physical labor, provided that the high intensity of labor, absorbs about 500 cubic centimeters of oxygen in one minute. However, this same worker in a calm state, in a standing position, absorbs no more than 300 cubic centimeters of oxygen in one minute.
From all of the above, we can conclude that a person's need for oxygen is directly affected by such factors as age, his lifestyle and labor intensity. And even the presence of a short lack of oxygen adversely affects the vital activity of the human body.
..how many liters of air does a person need per day?
The amount of air pumped by the human lungs in one minute in technology (and not only in it) is called pulmonary ventilation. This value varies over a fairly wide range. It depends both on the physical and physiological properties of a particular individual, and on the type of his activity. Usually, when calculating life support systems, it is assumed that at rest, pulmonary ventilation is 6 l / min, with light physical exertion - approx. 20 l / min, and with hard work - 60 or more l / min.
So, if I understand your question correctly, then 8.6-16.0 cubic meters of air will be pumped through the lungs of a person per day (if it was not plowed).
If a person sits in an unventilated room, then this is a completely different problem, also easily solved. In its standard form, the formula for people staying in a closed cell without ventilation usually determines the time that they can sit there, and has the following form:
T=[(V-0.08*n)*(Kd-K)]:M*n Here T is the allowable time spent in the chamber, hours, V is the volume of the chamber, l, n is the number of people in the chamber, Kd is the allowable concentration of carbon dioxide, l/l, K is the initial concentration of carbon dioxide before closing the chamber, l/l , M - average release of carbon dioxide by one person in the chamber, l/hour. Since we are faced with another task - to determine the required volume of the chamber with a known time spent in it, we will transform this formula and get:
V=(T*M+0.08Kd-0.08K):(Kd-K)
Next, we substitute the parameters.
You wrote that the required time is one day, so T=24; The release of carbon dioxide, if a person sits there for a day and does not prepare for a boxing match for the world title, I think it can be taken as an average daily, that is, 30 l / hour (if more, substitute the right one; less is unlikely). Kd, that is, the permissible concentration of carbon dioxide. There is a lot of room for imagination here. Who is sitting - young healthy foreheads or sickly and frail people? Children? Old men? In general, if the regime is gentle, then this value cannot be made more than 0.5%, and if young healthy people who can endure a possible slight headache jokingly, then nothing terrible will happen at 1% per day. Yes, by the way, you write about hypoxia, so this is precisely the lack of oxygen, oxygen starvation. We are calculating on carbon dioxide, so a possible unpleasant state will be called hypercopnia, that is, an excess of CO2.
So, we accept Kd in the range of 0.005-0.01, that is, from half a percent to a percent. Well, K is known, if the air is not gassed, then it is 0.03%, that is, 0.0003.
If we substitute and round up, then in the end we get the required volume of the chamber for one person from 72,000 to 144,000 liters, or from 72 to 144 cubic meters. The difference, of course, is due to the fact that we considered the permissible concentration in the range of 0.5-1%. In a volume of 72 cubic meters per day, one organism will breathe up to about a percent, in 144 - up to half a percent.
In general, I want to say that it is better to carry out such experiments, having gas analyzers for oxygen and carbon dioxide in the chamber. If it is difficult to get devices, you can at least buy glass tubes for express analysis and do it every hour. The fact is that sometimes individual individuals come across, guzzling oxygen (and, accordingly, releasing carbon dioxide) in very large quantities. For example, we have one such (I work on Mir submersibles), his gas exchange is approximately twice as high as that of normal people. Further, it is strictly forbidden to smoke in this volume, and if you plant a smoker, it is better for him to refrain from smoking for a day, otherwise carbon monoxide will inhale, and this is worse than CO2. Well, it is best, of course, to organize some simple life support system in a closed volume. Then at least in three cubic meters sit for a week - it would be something to drink and eat.
The amount of oxygen consumed by a person on an empty stomach in a state of muscle rest, lying down, is an indicator of the exchange necessary to maintain the vital functions of the body at rest, i.e., the basal metabolism. The basic human metabolism is characterized by oxygen consumption in the range of 200-250 ml / min with an energy consumption of approximately 1-1.2 kcal / min. Gender, age, weight and surface of the body, food composition, climatic conditions, ambient temperature, etc. influence the basal metabolism. 1 kcal per 1 kg of body weight per hour is taken as the norm for the energy basal metabolism of an adult.
Increased oxygen consumption during work is necessary for the oxidation of decomposition products of carbohydrates in the aerobic phase (lactic acid), fats, as well as for the resynthesis of nitrogen-containing substances in the anaerobic phase. The body's need for oxygen is greater, the harder the work. Within certain limits, there is a linear relationship between the severity of the work performed and oxygen consumption. This correspondence is ensured by strengthening the work of the cardiovascular system and increasing the diffusion coefficient of oxygen through the lung tissue. The diffusion coefficient increases from 50 at 450 kg/min to 61 at 1590 kg/min.
The amount of oxygen per minute required for the complete oxidation of decay products is called the oxygen demand, or oxygen demand, while the maximum amount of oxygen that the body can receive per minute is called the oxygen ceiling. The oxygen ceiling for people who are not trained for physical work is approximately 3 l / min, and for trained people it can reach 4-5 l / min.
Energy costs for dynamic negative work are approximately 50% of energy costs for dynamic positive work. Thus, moving a load along a horizontal plane is 9-16 times easier than lifting a load.
Rice. 1. Dynamics of oxygen consumption during physical work. Hatching in a cage - oxygen consumption during operation; horizontal shading - oxygen demand; vertical shading - oxygen debt. The drawing on the left is a medium-weight job; the picture on the right is working with progressive oxygen debt.
Oxygen consumption during dynamic positive work is shown in fig. 1. As can be seen from this figure, the curve of oxygen consumption at the beginning of work increases and only after 2-3 minutes is set at a certain level, which is then held for a long time (steady state). The essence of such a course of the curve is that at first the work is performed with incomplete satisfaction of the oxygen demand and, as a result, with an increasing oxygen debt, since energy processes in the muscle during its contraction occur instantly, and oxygen delivery due to the inertness of the cardiovascular and respiratory systems is slow . And only when the supply of oxygen corresponds to the full oxygen demand, a steady state of oxygen consumption occurs.
The oxygen debt, formed at the beginning of work, is repaid after the cessation of work, during the recovery period, during which oxygen consumption reaches its initial level. This is the dynamics of oxygen consumption during light and moderate work. In heavy work, a steady state of oxygen consumption essentially never occurs, the oxygen deficiency at the beginning of work is added to the oxygen deficiency formed during it. In this case, the oxygen consumption increases all the time up to the oxygen ceiling. The recovery period with such work is significantly lengthened. In the case when the oxygen demand during operation exceeds the oxygen ceiling, the so-called false steady state occurs. It reflects the oxygen ceiling, not the true oxygen demand. The recovery period is even longer.
Thus, the level of oxygen consumption in connection with the work can be judged on the severity of the work performed. A stable state of oxygen consumption during work may indicate that the oxygen demand is fully satisfied, that the accumulation of lactic acid in the muscles and blood does not occur, that it has time to be resynthesized into glycogen. The absence of a steady state and an increase in oxygen consumption during work indicate the severity of the work, the accumulation of lactic acid, which requires oxygen for its resynthesis. Even harder work is characterized by a false steady state.
The length of the recovery period for oxygen consumption also indicates greater or lesser workload. With light work, the oxygen debt is small. The resulting lactic acid, for the most part, has time to be resynthesized in the muscles into glycogen during work, the duration of the recovery period does not exceed several minutes. After hard work, oxygen consumption falls first quickly and then very slowly, the total duration of the recovery period can be up to -30 minutes or more.
The restoration of oxygen consumption does not mean the restoration of impaired functions of the body as a whole. Many body functions, such as the state of the respiratory and cardiovascular systems, the respiratory coefficient, biochemical processes, etc., have not yet reached the initial level by this time.
For the analysis of gas exchange processes, changes in the respiratory coefficient CO 2 /O 2 (RC) may be of particular interest.
With a steady state of oxygen consumption during the operation of the DC, it can indicate the nature of the oxidized substances. With hard work, DC rises to 1, which indicates the oxidation of carbohydrates. After work, DC can be more than 1, which is explained by a violation of the acid-base balance of the blood and an increase in the concentration of hydrogen ions (pH): an increased pH continues to excite the respiratory center and, as a result, carbon dioxide is intensively washed out of the blood with a simultaneous drop in oxygen consumption, i.e. in in the CO 2 /O 2 ratio, the numerator increases and the denominator decreases.
In a later stage of recovery, DC may be lower than the original final performance indicator. This is explained by the fact that in the recovery period, alkaline reserves of the blood are released, and carbon dioxide is retained to maintain normal pH.
During static operation, oxygen consumption is different. In the labor process, the most concrete expression of static work is the maintenance of a person's working posture. Working posture as a state of balance of the body can be carried out in the order of active opposition to external forces; at the same time, prolonged tetanic muscle tension occurs. This type of static work is very uneconomical in terms of innervation and energy. The working posture, in which balance is maintained by adapting to the direction of gravity, is much more economical, since in this case tonic rather than tetanic muscle tension is noted. In practice, both types of static work are observed, often replacing each other, but static work, accompanied by tetanic tension, is of primary importance from the point of view of labor physiology. The dynamics of oxygen consumption in this type of static work is shown in Fig. 2.
It can be seen from the diagram that during static stress, oxygen consumption is much less than the oxygen demand, i.e., the muscle works under almost anaerobic conditions. In the period immediately following work, oxygen consumption rises sharply, and then gradually falls (Lingard's phenomenon), and the recovery period can be long, so almost all oxygen demand is satisfied after work. Lingard gave the following explanation for the phenomenon he discovered. With tetanic “muscle contraction due to vascular compression, a mechanical obstacle to blood flow is created and thereby the delivery of oxygen and the outflow of decay products - lactic acid. Static work is anaerobic, therefore, a characteristic jump in the direction of increasing oxygen consumption after work is due to the need to oxidize the decay products formed during work.
This explanation is not exhaustive. Based on the teachings of N. E. Vvedensky, low oxygen consumption during static work can be due not so much to a mechanical factor as to a decrease in metabolism due to pressor-reflex influences, the mechanism of which is as follows. As a result of static stress (continuous impulses from the muscle), certain cells of the cerebral cortex enter a state of strong prolonged excitation, ultimately leading to inhibitory phenomena such as a parabiotic block. After the cessation of static work (pessimal state), a period of exaltation begins - increased excitability and, as a result, an increase in metabolism. The state of increased excitability extends to the respiratory and cardiovascular centers. The described type of static work is low-energy, oxygen consumption, even with very significant static stress, rarely exceeds 1 l / min, but fatigue can occur quite quickly, which is explained by changes that have occurred in the central nervous system.
Another type of static work - maintaining a posture due to tonic muscle contraction - requires little energy expenditure and is less tiring. This is explained by the rare and more or less uniform impulses from the central nervous system, characteristic of tonic innervation, and the peculiarities of the contractile reaction itself, rare and weak impulses, ductility and fusion of impulses, and the stability of the effect. An example is the habitual standing position of a person.
Rice. 2. Scheme of the Lingard phenomenon.
