A composition on light pollution

Without light, there would be no color, and everything in the world would be dark. For human beings, light is as indispensable as air, water and food. The eye is the most important sensory organ of the human body, and the human eye has strong adaptability to light, and the pupil can be adjusted with the light and shade of the environment. But if you look at things in poor light for a long time, your eyesight will be damaged. On the contrary, strong light can make people's eyes instantly blind, or even cause permanent damage. People must work, study and live in a suitable light environment. On the other hand, human activities may cause damage to the surrounding light environment, making the original straight light environment uncomfortable, which is light pollution. Light pollution is a special kind of pollution, which includes pollution caused by visible light, laser, infrared ray and ultraviolet ray. Glare is more common in visible light pollution. For example, whenever you walk along the road at night, the oncoming headlights of motor vehicles dazzle pedestrians, which is a kind of light pollution called glare. This dazzling light source is not only common on the road, but also often seen in some industrial and mining enterprises. For example, in the process of melting, smelting and welding, extremely strong light is also harmful light pollution. The danger of visible light pollution is the strong light when nuclear weapons explode. It can harm people's eyes in a considerable range. Without proper protective measures, people who have been engaged in welding, smelting and melting glass for a long time will suffer from eye injuries, blind spots will appear in their eyes, and cataracts will easily occur in their old age, which is the result of strong light hurting the lens of their eyes. Light Pollution in Modern Cities With the development and prosperity of modern cities, a new kind of urban light pollution is threatening people's health. This new urban light pollution is: shopping malls, companies, office buildings, restaurants, hotels and restaurants in cities and downtown areas; Hair salons and dance halls are decorated with large pieces of mirror glass, stainless steel plates and aluminum alloy doors and windows. Some even use mirror glass from the top to the bottom, which makes people feel as if they are in the world of mirrors, and the direction is difficult to argue, thus causing accidents. After sunset, when the night falls, all kinds of billboards, neon lights and waterfall lights on the busy streets of the city are lit up again, which makes people stay in artificial daylight. In the modern ballroom, people often use "color light source", "shining light source" and "rotating light source" to pursue the stimulating effect, which is dazzling and confusing. For these light pollution sources, scientists at home and abroad believe that urban light pollution can seriously interfere with people's nervous system and affect people's normal visual activities. In the season of strong sunshine, the mirror glass, glazed tiles, stainless steel, aluminum alloy plates, polished granite, marble and high-grade painted poles of buildings are dazzling, self-flowered and dazzling. According to scientific measurement, the light reflection coefficient of these decorative materials is more than 69%, even up to 9%, which is about 1 times larger than that of exterior decorative buildings with green space, forest, dark color or rough masonry, and completely exceeds the limit that the human body can bear, resulting in dizziness, headache, mental tension, distraction, palpitation, insomnia and dreaminess, loss of appetite, fatigue and other discomfort, and can also be induced. The influence of artificial self-hypnosis on people's physical and mental health can not be ignored. Strong light reflects into the room, destroying people's circadian rhythm, making it difficult for people to fall asleep, even leading to insomnia and neurasthenia, causing mental fatigue at work and prone to safety accidents. Laser pollution laser is a special kind of light emitted by the laser, which has a single color, a straight beam and great intensity. At present, there are thousands of laser colors, which have many advantages and are widely used. However, because of the concentrated energy and high brightness of laser, it is more harmful than other light. If the laser energy is continuously emitted, the maximum power can reach tens of thousands of kilowatts, and the instantaneous power can reach trillions of kilowatts, and a thick steel plate can be pierced in seconds, not to mention people. Therefore, the laser fork is called dead light. There are two aspects of environmental pollution caused by laser: many substances (such as dust) are gasified when the laser beam passes through the air, which causes air pollution; On the other hand, laser will not only harm the conjunctiva, iris and lens of the eyes, but also directly harm the deep tissues and nervous system of the human body. At present, laser is mainly used in laser industry (cutting, drilling, etc.), surveying and mapping, medical treatment and scientific research. Infrared pollution infrared is widely used in military, satellite, industry, agriculture, health research and so on. Infrared pollution can not be ignored. Infrared ray is a kind of invisible light, and its main function is heat. Strong infrared ray can cause skin injury and skin burn similar to scald. Infrared rays are also harmful to human eyes, which can damage the retina of the fundus, and may also cause corneal burns and iris damage. Ultraviolet light pollution ultraviolet light is also a kind of invisible light, which is widely used in production, national defense and medicine. For example, disinfection, sterilization, treatment of certain skin diseases and rickets, etc., and also used for satellite detection of the ground. However, the harm of ultraviolet rays to human body is mainly harmful to human eyes and skin. Long-term excessive exposure to ultraviolet rays will make the cornea of eyes show the damage from rabbits, which will cause "photodermatitis" on the skin. In severe cases, it will cause skin peeling and necrosis, and even cause skin cancer. The harmful effect of ultraviolet rays on the skin is also a kind of light pollution.

[ Edit this paragraph] What is light pollution

The problem of light pollution was first put forward by the international astronomical community in the 193s. They believed that light pollution was a negative impact on astronomical observation caused by the bright sky caused by outdoor lighting in cities. Later, Britain and the United States and other countries called it "interference light", while in Japan it was called "light damage".

At present, there is no clear definition of light pollution at home and abroad. It is generally believed that light pollution refers to all kinds of light that affects the natural environment, adversely affects human normal life, work, rest and entertainment, damages people's ability to observe objects, causes human discomfort and harms human health. Optical radiation with a wavelength from 1 nanometers to 1 millimeter, that is, ultraviolet radiation, visible light and infrared radiation, may become light pollution sources under different conditions.

light pollution in a broad sense includes some things that may have adverse effects on people's visual environment and health, including the reflection of books, papers and wall coatings that are common in life, and even the "light" of roadside color advertisements. This shows the wide range of light pollution. In daily life, people's common light pollution is mostly caused by the dizziness of pedestrians and drivers caused by the reflection of mirror buildings, and the discomfort caused by unreasonable lighting at night.

[ Edit this paragraph] Classification of light pollution

According to different classification principles, light pollution can be divided into different types.

internationally, light pollution is generally divided into three categories, namely white light pollution, artificial daylight pollution and colored light pollution.

1. White light pollution

When the sunlight is strong, the glass curtain wall, glazed tile wall, polished marble and various paints of buildings in the city reflect light, which is bright and dazzling. Experts have found that people who work and live in a white light polluted environment for a long time will suffer different degrees of damage to their retina and iris, and their vision will drop sharply. The incidence of cataract is as high as 45%. It also makes people dizzy and upset, and even causes insomnia, loss of appetite, depression, physical weakness and other similar neurasthenia symptoms.

In summer, the strong reflected light from the glass curtain wall enters the nearby residential buildings, which increases the indoor temperature and affects the normal life. Some glass curtain walls are semi-circular, and the convergence of reflected light is easy to cause fire. Drivers driving in the hot sun will be suddenly attacked by the reflected light from the glass curtain wall, and their eyes will be strongly stimulated, which will easily lead to car accidents.

according to the research of optical experts, the reflected light of mirror building glass is stronger than sunlight, and its reflectivity is as high as 82% ~ 9%, and the light is almost completely reflected, which greatly exceeds the range that human body can bear. People who work and live in a white light polluted environment for a long time are prone to vision loss, dizziness, insomnia, palpitation, loss of appetite and depression, which will change people's normal physiology and psychology, and will induce some diseases for a long time. Experts have found that people who work and live in a white light polluted environment for a long time will suffer different degrees of damage to their retina and iris, and their vision will drop sharply. The incidence of cataract is as high as 45%. In summer, the strong reflected light from the glass curtain wall enters the nearby residential buildings, which destroys the original good indoor atmosphere and increases the average room temperature by 4℃ ~ 6℃. Affect normal life.

* glare pollution

The headlights used for lighting when the car is driving at night and the unreasonable lighting arrangement in the factory will cause glare. In some workplaces, such as railway stations and airports, as well as the central control room of automation enterprises, too many and too complicated signal lamp systems will also reduce the visual acuity of workers, thus affecting work efficiency. The strong light generated by the welding torch will also hurt people's eyes without proper protective measures. Workers who work under strong light for a long time (such as smelting workers, melting workers, glass blowers, etc.) will also suffer from strong light.

2. Artificial daylight

After nightfall, advertising lights and neon lights in shopping malls and hotels are dazzling. Some strong beams even go straight into the sky, making night like day, which is called artificial day. In such a "city that never sleeps", it is difficult to fall asleep at night, which disturbs the normal biological clock of the human body and leads to low work efficiency during the day. Artificial daylight can also harm birds and insects, and strong light may destroy the normal reproduction process of insects at night.

At present, the widespread and excessive use of lights in big cities makes the sky too bright to see the stars, which affects astronomical observation and aviation, and many observatories are forced to stop working. According to astronomical statistics, when the sky is not polluted by light at night, about 7, stars can be seen, while in big cities where street lights, background lights and landscape lights are scattered randomly, only about 2 to 3 stars can be seen.

3. colored light pollution

black lights, rotating lights, fluorescent lights and flashing colored light sources installed in dance halls and nightclubs constitute colored light pollution. According to the measurement, the intensity of ultraviolet rays produced by black light is much higher than that in sunlight, and the harmful effects on human body last for a long time. If people receive this kind of radiation for a long time, they can induce nosebleeds, tooth loss, cataracts, and even leukemia and other cancers. Color light source is dazzling, which is not only bad for eyes, but also interferes with the central nervous system of the brain, making people feel dizzy and have symptoms such as nausea, vomiting and insomnia. The latest research by scientists shows that color light pollution not only damages people's physiological functions, but also affects people's psychology. The measurement of "spectral chromaticity effect" shows that if the psychological influence of white light is 1, blue light is 152, purple light is 155, red light is 158, and black light is the highest, which is 187. If people are exposed to colored lights for a long time, their psychological accumulation effect will also cause physical and mental diseases such as burnout, dizziness, loss of libido, impotence, irregular menstruation and neurasthenia to varying degrees.

In addition, some scholars also divide light pollution into outdoor visual environmental pollution, indoor visual environmental pollution and local visual environmental pollution according to the scope of light pollution. Among them, outdoor visual environmental pollution includes building exterior walls, outdoor lighting, etc. Indoor visual environmental pollution includes indoor decoration, indoor bad light and color environment, etc. Local visual environmental pollution includes books, papers and some industrial products.

* Laser pollution

Laser pollution is also a special form of light pollution. Because laser has the characteristics of good directivity, concentrated energy and pure color, and the light intensity when it reaches the fundus can be increased by millions to tens of thousands of times after the laser passes through the lens of the human eye, laser has a great harm to the human eye. Part of the laser spectrum belongs to the ultraviolet and infrared range, which will damage the conjunctiva, iris and lens. High-power laser can harm deep tissues and nervous system of human body. In recent years, laser has been widely used in medicine, biology, environmental monitoring, physics, chemistry, astronomy and industry, and people pay more and more attention to laser pollution.

* infrared pollution

in recent years, infrared has been widely used in military affairs, artificial satellites, industry, health, scientific research and other aspects, so the problem of infrared pollution has also arisen. Infrared ray is a kind of thermal radiation, which can cause high temperature damage to human body. Strong infrared rays can cause skin damage, which is similar to scalding, first burning pain, and then burning. There are several different situations in which infrared rays can harm the eyes. The infrared rays with the wavelength of 75 ~ 13 angstroms have a high transmittance to the cornea, which can cause damage to the fundus retina. Especially near 11, angstroms, infrared rays can make the anterior media of the eye (cornea, lens, etc.) not damaged and directly cause fundus retinal burns. Almost all infrared rays with a wavelength of more than 19, angstroms are absorbed by the cornea, which will cause corneal burns (opacity and white spots). Most of the energy of infrared rays with a wavelength of more than 14, angstroms is absorbed by cornea and intraocular fluid, and cannot penetrate the iris. Only infrared rays below 13, angstroms can penetrate the iris, causing iris damage. Long-term exposure of human eyes to infrared rays may cause cataracts.

* ultraviolet pollution

ultraviolet was first used in disinfection and some technological processes. In recent years, its application scope has been expanding, such as for satellite detection of the ground. The effect of ultraviolet light varies according to its wavelength. The vacuum ultraviolet part with the wavelength of 1 ~ 19 angstrom can be absorbed by air and water. Most of the far ultraviolet part with the wavelength of 19 ~ 3 angstroms can be strongly absorbed by biomolecules; The near ultraviolet part with the wavelength of 3 ~ 33 angstrom can be absorbed by some biomolecules.

ultraviolet rays mainly harm the cornea and skin. The ultraviolet rays that cause corneal damage are mainly 25 ~ 35 angstroms, and the wavelength of 288 angstroms is the strongest. Repeated exposure of cornea to ultraviolet rays does not increase its tolerance to ultraviolet rays. The harmful effect of ultraviolet rays on cornea is a very painful corneal leukoplakia injury called photophobia. In addition to severe pain, it also leads to tears, blepharospasm, conjunctival congestion and ciliary muscle twitching. The harmful effects of ultraviolet rays on the skin mainly cause erythema and small blisters, and in severe cases, the epidermis will be necrotic and desquamate. The skin of human chest, abdomen and back is most sensitive to ultraviolet rays, followed by forehead, shoulders and buttocks, and then the soles of feet and the back of hands. Ultraviolet rays with different wavelengths have different effects on the skin, and ultraviolet rays with wavelengths of 28 ~ 32 Angstroms and 25 ~ 26 Angstroms have the strongest effects on the skin.

light pollution in a broad sense also includes:

visual pollution

refers to the messy visual environment in the urban environment. For example, the messy wires, telephone lines, messy garbage, messy stalls and colorful advertising posters on both sides of the city streets.

There are many other ways to classify light pollution. For example, on Wikipedia, we can see that light pollution can be divided into the following categories:

light intrusion

This kind of "pollution" mainly refers to the fact that too strong light sources affect other people's lives.