I. The environment characteristics of the plateau
1. Hypoxia
From sea level to an altitude of 100,000 meters, the content of oxygen in the air is 21%. However, the air pressure decreases as the altitude increases, resulting in thin air, so the oxygen pressure also decreases. It is estimated that at an altitude of 4,270 meters above sea level, the oxygen pressure is only 58% of sea level. Therefore, although the relative proportion of oxygen in the atmosphere has not changed, the absolute amount of oxygen has become smaller due to the thin air, which has led to the lack of oxygen.
2. cold
According to meteorological measurements, the temperature will drop by 1 degree for every 150 meters above sea level. For every 1,000 meters above sea level, the temperature drops by 6.5 degrees. Therefore, the temperature in the plateau is colder than in other areas at the same latitude.
3. Low humidity
The low humidity in the plateau increases the amount of water discharged from the body. According to calculations, 1.5 litres of water is discharged through the breath every day on the plateau, and 2.3 liters of water is discharged through the skin. Without sweating, it reaches 1 times the total body fluid discharge of the same latitude and plain area.
4. Strong sunshine radiation
At an altitude of 3,600 meters above sea level, the ionizing radiation in the universe, ultraviolet light intensity and penetration into the skin are three times sea level. In addition, the reflection of these rays through snow is also very strong. It has been determined that 90% of ultraviolet rays can be reflected back to the surface by snow, and the reflectance of grassland is only 9%-17%. In other words, due to the effect of snow, the human body will suffer from double ultraviolet radiation.
The environment characteristics of the plateau are truly extraordinary. In this regard, the human body does not passively cope, but must make corresponding adjustments according to the environment. For short-term tourists, adjustments are temporary, and people who have lived on the plateau for thousands of years have already developed adaptive changes. Let us look at the changes people will undergo in the highlands.
1. Blood system
Two hours after entering the plateau, due to lack of oxygen, the body began to produce too many red blood cells to adapt to the hypoxic environment. Hemoglobin increased by 1.1 grams per week. After about six weeks, the body’s hemoglobin will increase to 1.4 times the original level. 20 grams or so. This phenomenon of high hemoglobin disease is common in the plateau region, but after returning to low altitudes, high hemoglobin disease will gradually return to its original level, and mild anemia will appear after 3 weeks of continued decline. Then hemoglobin levels will rise to normal. Therefore, one month or so after returning from the plateau to the low altitude region, it is not appropriate to return to the plateau. Otherwise, the human body in anemic conditions is more prone to high altitude disease.
2. Respiratory system
Due to the low oxygen pressure, the human body will hyperventilate and ventilate due to lack of oxygen. At sea level, the body needs 250 ml of oxygen per minute, which means that 5 liters of air must be inhaled to exchange gas in the lungs. At a height of 3,000 meters above sea level, the human body must inhale 7.5 litres of air to meet the body's need for oxygen. At this time, people will feel shortness of breath, and if they add exercise, they will feel more irritated.
However, living on the plateau is conducive to the control of chronic bronchial asthma, which is similar to the principle of hypobaric oxygen used in the treatment of bronchial asthma, which is equivalent to the pressure in the 2000-2500 meters high area. The plateau has four distinct seasons, low humidity, high levels of ozone in the air, and high solar radiation, all of which are beneficial to the recovery of asthma patients. In fact, local residents rarely suffer from respiratory diseases.
3. Circulatory system
As a result of lack of oxygen, the general emotional excitement and slight movement of tourists will accelerate the heart rate. At the beginning of the plateau, the morning pulse of the human body (the pulse of early morning wake) is about 20% higher than the sea level. After 10 days, the morning pulse should be reduced to its original level. Therefore, the ability of the human body to adapt to the plateau can be judged by measuring the degree of change in the morning pulse and returning to the original level. The incidence of coronary heart disease, arteriosclerosis, hypertension, diabetes, obesity and other diseases is very low in the plateau. Local people have low blood cholesterol and triglyceride levels.
4. immune system
In the highland environment, T lymphocytes, which are responsible for human immunity, will be damaged, making the body very vulnerable to bacterial infections.
5. Reproductive system
At a height of 4300 meters above sea level, the number and activity of sperm were significantly reduced in men, and abnormal sperm morphology increased. But don't worry, this is only temporary. Back to low altitude, this phenomenon can gradually return to normal.
At an altitude of 4300 meters above sea level, the incidence of dysmenorrhea and menstrual disorders increased in women. Spontaneous abortion, premature birth and congenital malformations are very common, which is one of the reasons why the birth rate of the snow-covered plateau population has been relatively low. Of course, these conditions are not a problem for tourists.
Third, experience high altitude sickness
After entering the plateau area, the human body will make corresponding adjustments according to environmental changes. However, because tourists have a short stay and the rate of human adjustment is limited, high altitude disease may still occur. Here are the highlights of identifying high altitude diseases. Remember that once you discover that you may be suffering from high altitude sickness, the first thing you must do is to get to the hospital quickly. Many altitude sicknesses are very dangerous and must be treated promptly.
1. Acute mountain sickness
The most common occurs in the first and second days of the plateau above 3,300 meters above sea level, especially the first 6-9 hours of the first day.
Identifying points: Headache, plus any of the following symptoms: general fatigue, dizziness, insomnia, nausea, and vomiting.
2. High altitude pulmonary edema
The mortality rate of untreated high altitude pulmonary edema was 40%.
Identifying points: There are two or more of the following: breathing difficulties during rest, coughing, weakness and decreased activity, a sense of blockage in the chest, pale skin and cyanosis, and increased heart rate.
3. Alpine brain edema
The mortality rate of untreated alpine brain edema was 14%.
Identification points: There are symptoms of acute mountain sickness, unable to go straight, there are mental disorders.
4. Chronic mountain sickness
After adapting to the plateau environment for a certain period of time, it has reappeared to adapt to the plateau environment.
Identification points: fatigue, headache, dizziness, cyanosis, lack of endurance during exercise, etc.
5. other
At different altitudes, tourists may experience the following symptoms:
1500 meters: Visual acuity in the dark.
1500-1800 meters: Reduced or lack of advanced thinking function.
3300 meters: Simple arithmetic becomes very difficult.
4,600 meters: Writing and considering issues are affected.
More than 5500 meters: 100% of visitors suffer from pharyngitis and bronchitis.
IV. Preparation before entering the plateau
1. From the day you decide to go to the plateau, you should increase the time for anaerobic exercise in your daily life. An anaerobic exercise refers to a vigorous exercise with a large amount of exercise, which can cause the body to have a certain tolerance to hypoxia.
2. Prepare some commonly used drugs. In the plateau region, the respiratory system is very susceptible to infection, and antibiotics such as amoxicillin and roxithromycin should be taken. Plateaus have limited sanitation and are prone to gastroenteritis, which can be accompanied by ciprofloxacin or sulfa drugs. The diuretic acetazolamide must also be prepared, which is the main drug for preventing and treating altitude sickness. It can eliminate paroxysmal nocturnal apneas, increase night-time sleep quality, and reduce morning headaches. Take the method 125 mg twice a day, or 250 mg once a day. Take it 24 hours before entering the plateau.
3. The temperature difference between the morning and evening in the plateau area can reach 15-20 degrees, and it is necessary to bring enough cold-proof clothing.
4. Get ready for UV protection.
5. If you fly directly into the plateau area and start one night before sailing in a low altitude area, make sure you have enough sleep, do not eat greasy food or drink alcohol. If you enter the plateau area by car or train, you must plan your daily trip. It is best to increase the altitude every day by 400-600 meters. At each new height, it is necessary to rest for a few days so that physical strength will gradually recover and adapt to the hypoxic environment at high altitude. If you are on foot or on a bicycle, you must ask experts to develop a scientific climbing plan based on your physical condition.
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