What does air humidity mean? What difference does the size make to people's feelings?

A physical quantity indicating the degree of dryness of the atmosphere. At a certain temperature, the less water vapor is contained in a certain volume of air, the drier the air is; the more water vapor is, the more humid the air is. The degree of dryness and humidity of the air is called "humidity". In this sense, it is often expressed by physical quantities such as absolute humidity, relative humidity, comparative humidity, mixing ratio, saturation difference and dew point; if it represents the weight of liquid water in wet steam as a percentage of the total weight of the steam, it is called steam humidity.

Research shows that when the humidity is too high, the pineal gland in the human body secretes a larger amount of pineal hormone, which causes the concentration of thyroxine and epinephrine in the body to decrease relatively, and the cells become If people are "lazy", they will be listless and depressed. People who work and live in places with high humidity for a long time are also prone to rheumatism; when the humidity is too low, evaporation is accelerated, and the dry air can easily take away moisture from the human body, drying the skin and irritating the nasal mucosa, so the dry and cold air in autumn and winter When invaded, respiratory symptoms can easily be induced. In addition, too high or too low air humidity is conducive to the reproduction and spread of some bacteria and viruses. Scientific measurements show that when the air humidity is higher than 65% or lower than 38%, germs reproduce the fastest. When the relative humidity is between 45% and 55%, germs die faster.

Relative humidity usually acts on the human body together with temperature and air pressure. Modern medical meteorological research shows that the appropriate relative humidity for the human body is: when the room temperature is 25°C in summer, the relative humidity is controlled at 40%-50%, which is more comfortable; when the room temperature is 18°C ??in winter, the relative humidity is controlled at 60%-70%. During the dog days of summer, due to the effects of high temperature, low pressure, and high humidity, human body sweat is not easily discharged and evaporated after sweating, which makes people irritable, tired, and loses appetite; in winter, the humidity is sometimes too low and the air is too dry, which can easily cause Upper respiratory tract mucosal infection and cold. According to scientific experiments, when the daily change in temperature is greater than 3°C, the daily change in air pressure is greater than 10 hPa, and the daily change in relative humidity is greater than 10%, the incidence of arthritis will increase significantly.

The high temperature index that causes human death is also closely related to air humidity. When the temperature and humidity reach a certain limit, the human body's heat cannot be dissipated, and the body temperature will rise until it exceeds the human body's heat tolerance limit, and the person will die. Therefore, my country's disastrous weather standards are as follows: the highest temperature in the south of the Yangtze River is higher than 38°C, or the highest temperature reaches 35°C, and the relative humidity is higher than 61%; the highest temperature in the north of the Yangtze River reaches 35°C, or the highest temperature reaches 30 ℃, while the relative humidity is higher than 64%.

In summer, when the humidity increases and the water vapor becomes saturated, it will inhibit the body's heat dissipation function, making people feel very stuffy and irritable. In winter, when the humidity increases, heat conduction will be accelerated by about 20 times, making people feel colder and more depressed. Due to damage to the joint synovium and surrounding tissue in the affected area, patients with arthritis have a weakened ability to resist external stimulation and cannot adapt to intense cooling, which may worsen the condition or worsen the pain. If the humidity is too low, a large amount of water will be lost in the upper respiratory tract mucosa, making people feel dry and dry, and may even cause sore throat, hoarseness, and nosebleeds, which may lead to colds. Survey research also shows that when the relative humidity reaches above 90%, 26°C will make people feel like 31°C. Dry air can absorb sweat at the same rate as human sweat glands produce sweat, making us feel cool. However, the air with high humidity is already full of moisture and is unable to absorb any more moisture. Therefore, sweat has to accumulate on our skin, causing our body temperature to continue to rise, and at the same time, our mind is overwhelmed.

1. Humidity and comfort

The "standard effective temperature index" is obtained based on skin sensation, physiological response and thermal effect, which indicates that the relative humidity is within the range of 20% to 50%

and the dry bulb temperature Within the range of 23 to 25°C, it is the best temperature and humidity environment for the human body to feel comfortable.

2. Humidity and Health

Improper humidity can easily make people sick and affect human health. Many pathogenic bacteria live longer in environments that are too dry or too humid, and they live longer in environments with high humidity. Studies have shown that when the relative humidity is 35% to 50%, the survival time of bacteria is reduced, and skin diseases caused by dryness are also relatively reduced.

In the hot summer, the usage rate of air conditioners in offices and homes has greatly increased. While you enjoy the coolness and comfort brought by air conditioning, do you also experience the discomfort caused by the dryness of air-conditioned rooms? Many residents who use air conditioners said that sleeping with the air conditioner on all night feels like dehydration. "Dry throat, dry eyes, chapped lips, all in all very uncomfortable."

The key to the uncomfortable symptoms caused by turning on the air conditioner all night in summer is that the current air conditioner has a powerful dehumidification function, which causes the air in the air-conditioned room to be abnormally dry. He said that the indoor air quality standards promulgated by the country require the humidity of air-conditioned rooms in summer to be 40% to 80%, but according to testing by relevant departments, the actual humidity in air-conditioned rooms in summer is as low as 20% to 30%. If the humidity in the room is too low, it will have an extremely negative impact on the mucosal tissue of the human body, making it easy for bacteria and viruses to invade and spread. The respiratory tract, eyeballs and skin will be most seriously affected.

Some people will experience symptoms such as dry lips, nose and throat discomfort, respiratory tract irritation, and inflammation, which especially affects susceptible groups such as the elderly and children. At the same time, dryness will cause the body's moisture content to become imbalanced, and the skin will lack elasticity and luster. Accelerates the aging, tightness and roughness of the cortex; the lens of the eye will feel dry and astringent due to dryness.

Folk prescription: increase air humidity

There are now two folk prescriptions for solving the problem of dryness in air-conditioned rooms for your reference. The main purpose is to increase the humidity of the room. Tests show that the actual effect is not great, and it cannot solve the indoor drying problem well.

1. Put a basin of water or wet the floor in the air-conditioned room. Before going to bed, put a basin of cold water in the room; or use a wet mop to wipe the entire room floor to increase the air humidity.

2. Keep some green aquatic plants such as Lucky Bamboo and Begonia in the room, or raise goldfish. The water slowly evaporates to relieve the dryness of the air