Internationally, light pollution is divided into three categories: artificial sunlight pollution, colored light pollution and white light pollution.
I. Types of light pollution
1. Artificial sunlight
After nightfall, advertising lights, neon lights and waterfall lights in shopping malls and hotels are dazzling, making people feel that night is like day, which is called artificial sunlight. Due to the strong light reflection, the nearby room will be as bright as day. In such a "city that never sleeps", it is difficult to fall asleep at night, which disrupts the normal "biological clock" of the human body. Artificial sunlight will also harm birds and insects, because strong light will destroy the normal reproduction of insects at night and destroy the ecological balance.
Animal protectors, astronomers and many city residents oppose this kind of artificial sunlight because it wastes electricity and causes a kind of light pollution. Animal protectors say that dazzling light is the chief culprit in killing birds and insects. Because strong light will, for example, find the remains of more than 500 birds under the Washington Monument decorated with China lanterns in an hour and a half.
Another example is the giant billboard on Musical Instrument Street in the British Palace. At night, the lights are brightly lit, and a beam of laser-like light is emitted in the dark, and planes are often seen nearby. Whether strong light will affect the pilot's line of sight is quite worrying. Neighboring residents, such as residents of Jianwei Garden and Gem House, also complained that the bright lights of billboards reflected their gratitude, making their homes look like daytime, and it was difficult for them to fall asleep after tossing and turning, which led to depression and affected their normal daily life.
An important sign of a modern and complex city is that after nightfall, billboards and neon lights in hotels and shopping malls in the noisy city that never sleeps are dazzling, and incandescent lamps shine as bright as day. This dazzling light pollutes people's vision and affects people's physical and mental health.
When people step into the busy city streets, they often reflect dazzling white light. Many large shopping malls are decorated with white mirrors or aluminum alloys. What's more, some shopping malls use large mirror glass from beginning to end, which is almost in a mirror world, making people confused.
According to the measurement, the reflection coefficient of white paint surface is 69 ~ 80%; The reflection coefficient of mirror glass is 82 ~ 88%, which is about 10 times larger than that of green grass, forest, dark or rough masonry, which greatly exceeds the physiological adaptation range of human beings and becomes a pollution source, endangering human health. White light pollution in some developed countries has begun to formulate corresponding laws to limit and stop it, and has attracted people's attention. In the design and construction departments, it is forbidden to decorate the facades of high-rise buildings and shopping malls with reflective materials, and it is also forbidden to decorate the interior with large mirrors.
According to the investigation of Bavarian Environmental Problems and State Development Planning Bureau, among 238 respondents, 2/3 think that artificial sunlight affects health, and 84% report that it affects night sleep. To this end, people have to seal the bedroom windows or install dark curtains. This day and night living environment will do harm to people's psychology.
Although people have found that strong light has become another pollution source besides noise, waste gas and waste water, and there are many complaints, it has not attracted the attention of relevant departments and people so far.
2. Color light pollution
Black lights, rotating lights, fluorescent lights and flashing light sources installed in modern dance halls and nightclubs constitute color light pollution. According to the measurement, black light can produce ultraviolet with the wavelength of 250~300 nm, which is much higher than that in sunlight. If people are exposed for a long time, it will 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, causing nausea and vomiting, decreased eyesight, inattention, low sexual desire and other symptoms.
Experiments by researchers at Cambridge University in England have proved that colorful neon lights and dazzling strong light waves can lead to genetic degeneration of a large number of cells in organisms, increase abnormal cells, disturb the natural balance of the body, and cause "light damage syndrome" such as dizziness, irritability and insomnia.
According to the investigation and measurement of laser equipment in dozens of dance halls by relevant health departments, the laser radiation pressure in most dance halls has exceeded the limit. This high-density thermal beam is concentrated on the retina after passing through the lens of the eye, and the focal temperature can be as high as 70 degrees Celsius, which is very harmful to the eyes and brain nerves.
3. White light pollution
In the season of strong sunshine, many buildings in the city, such as glazed tile walls, polished marble, aluminum alloy curtain walls, glass curtain walls and various paints, reflect light and are dazzling, which is white pollution. According to the doctor of Futian Hospital, people who work and live in the environment polluted by white light 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%, which can also make people dizzy and upset, and even cause insomnia, loss of appetite, depression, physical weakness and other similar symptoms of nervous decline. In summer, the strong reflected light from the glass curtain wall enters the nearby residential buildings, which raises the indoor temperature and affects 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 suddenly be attacked by the reflected light from the glass curtain wall, and their eyes will be strongly stimulated, which is prone to car accidents.
The human body bears the brunt of light pollution. Instantaneous strong light irradiation can make people temporarily blind, and ordinary light pollution can also cause damage to the cornea and iris of human eyes, inhibit the function of retinal photoreceptor cells, and thus cause visual fatigue and vision decline.
Second, our investigation-investigation on the source and harm of light pollution
Light pollution is caused by light pollution sources. Through investigation, we found that pollution sources and their hazards mainly include:
1. Light pollution caused by computer screen and its harm
Before human civilization, it was "light" that lit up the world. In the early stage of the industrial revolution, light was called "the light of existence", in the late stage of the second industrial revolution, it was called "the light of development", and in 2 1 century, it became "the light of information". "Light" is the source of life. People have been exploring light unremittingly. As time goes on, people let light serve themselves more effectively. In the 1970s, computers began to spread all over the world. In 1990s, computers entered the China market. Since then, a lot of office copywriting work has shifted from the workbench to the luminous screen. The way of working has changed from a single reading and writing on horizontal paper to a vertical computer screen.
Computer workers scan files, keyboards and screens back and forth with their eyes more than 10 thousand times a day. The way of working has completely changed, and the incidence of "computer eye" is increasing day by day. We visited several printing houses in Futian District. Under normal working conditions, there are as many as four reflective points on the screen. 70% employees complained about eye pain, fatigue and brain swelling. These conditions are directly related to traditional lighting methods and lamps. Traditional lighting methods and lamps are the interference and influence of the visual environment, which causes damage to the visual organs, while the visual nerve directly acts on the brain, leading to dizziness, fatigue, boredom and even irritability.
2. Light pollution caused by "noise light" and its harm
The so-called "noise light", as its name implies, is the light that interferes with people's normal life, work and study activities, makes people feel bored and angry, and then has a bad influence or even harm on people's physical and mental health. The difference between noise pollution and noise pollution is that noise harms people's health through hearing, while noise harms people's health through vision. Noise pollution mainly refers to white light pollution and artificial sunlight.
From the end of 1970s to the beginning of 1980s, a large number of manufacturing processes such as heating, spraying, ion exchange, vacuum evaporation or chemical coating were adopted abroad, and copper, chromium, nickel, iron, gold and other metals were coated on one side of building glass to form a colored film reflecting light, which is called mirror building. Mirror buildings, such as large mirrors or aluminum alloy facades in shopping malls and restaurants, reflect more strongly than sunlight, which brings a lot of inconvenience to adjacent buildings and residents, as if there is a "sun", which makes people feel unbearable heat. Drivers are dazzled by this reflection and are prone to traffic accidents.
To reduce the harm of noise light, a new urban pollution, it is imperative to strengthen urban planning management, rationally arrange light sources, strengthen the management of advertising lights and neon lights, prohibit the use of high-power and strong light sources, control the use of high-power civil laser devices, and restrict the use of materials with high reflection coefficient. As ordinary people, on the one hand, don't stay in noise and light pollution areas for a long time. If the light is too strong, you can install blinds or double curtains in the room and adjust them according to the light intensity; On the other hand, the whole people began to plant trees and flowers around buildings, and extensively planted turf to improve and adjust the lighting environment.
3. Light pollution caused by glass curtain wall and its harm
The development of modern architectural technology has broken the traditional boundary between wall and window. The appearance of glass curtain wall is an example, which has become a symbol of modern architecture. According to incomplete statistics, the existing glass curtain wall area in China has exceeded 9 million square meters, and it is still developing. Many hotels also like to use glass curtain walls. In fact, this one-sided pursuit of beautiful architectural appearance and neglect of ecological negative effects such as light pollution are not conducive to environmental protection.
All kinds of visible light, invisible light and reflective substances that enter the ecological environment will cause the deterioration of the ecological environment if they exceed the indicators that normal survival can bear. Experts call this phenomenon light pollution. They regard the glass curtain wall, the main carrier of urban light pollution, as a "hidden danger of the city" and a "bright killer". The harm of glass curtain wall is mainly manifested in the following aspects:
(1) affecting health
The glass curtain wall used for decoration in street-facing buildings is like a large mirror of dozens or even hundreds of square meters. When the sun is strong, its reflection coefficient exceeds 75%, even as high as 90%. The sunlight it reflects is easy to make people in it nearsighted, tired, migraine and tachycardia. For drivers, it is easier to get dizzy and confused, which leads to traffic accidents. In summer, the glass curtain wall reflects sunlight into the residents' rooms, which can increase the room temperature by 4-6℃ compared with ordinary houses, and easily lead to the aging of household appliances.
② Fire hazard
Some glass curtain walls themselves have fire hazards, especially those concave buildings, whose glass curtain walls objectively form a giant condenser. In Shenzhen, a car parked near the commercial building was burnt by the focusing effect of the glass curtain wall of the commercial building. A fire caused by the focus of glass curtain wall also happened in Berlin, Germany.
③ Radioactive pollution
Excessive light radiation has a negative impact on human life and production environment. Infrared ray is a kind of thermal radiation. Strong infrared rays can cause skin damage. Different wavelengths of infrared rays will have different harmful effects on eyes. Ultraviolet rays mainly harm cornea and skin. The ultraviolet rays that cause corneal damage are mainly at the wavelength of 2500-3050 Angstroms, of which 2880 Angstroms is the strongest. The harmful effects of ultraviolet rays on the skin mainly cause erythema and blisters, and in severe cases, the epidermis will be necrotic and desquamate.
Some glass curtain walls (such as brown ones) contain some kind of metallic cobalt, which is itself a radioactive element. Under the irradiation of sunlight, people are more vulnerable to radioactive pollution, which will destroy the hematopoietic function of human body and cause diseases such as cancer. Relevant persons pointed out that since light pollution cannot be eliminated by decomposition, transformation and dilution, prevention can only be strengthened. It is understood that western developed countries have a clear definition of the luminosity of glass curtain walls, and if it exceeds the definition, it is regarded as light pollution. Germany, Japan and other seven industrial countries have defined the new technology of glass curtain wall. In China, Beijing rejected more than 60 glass curtain wall designs; Not long ago, Shanghai also issued a local law to cancel the glass curtain wall.
4. Light pollution caused by too strong, too miscellaneous and too messy light and its harm.
The second form of light pollution is excessive light and light that changes too fast, which causes interference and harm to people. At present, many hotels pay attention to the luxurious decoration of buildings, and generally use large pieces of mirror glass, polished granite, marble veneer, tempered glass and stainless steel to package the whole building, plus bright aluminum alloy plates and advanced coatings. It is especially reflective after sunlight. There are also some cars with mirror-like glass or blue tempered glass. Facing the sun, pedestrians will be blinded by strong light. According to the measurement, the reflection coefficient of these decorative buildings is above 65%, and some can even reach 90%, which is about 10 times higher than that of external decorative buildings such as rubble masonry, and far exceeds the limit that human body can bear.
Glare can come from many aspects, such as the reflection of solar light by glass or mirror, the spotlight or flashlight of camera, the lighting of cars driving at night, the outline lights of large buildings, the lighting of railway stations and airports, etc. , all belong to glare pollution, which will cause harm to human body.
Some lights, such as car lights, airport lights, lightning, etc. It won't look very bright during the day and it won't make people feel uncomfortable. But if they appear at night, they are particularly bright against the black background, which is easy to cause harm to human eyes. Because the human eye has two kinds of photosensitive cells-cone cells and rod cells, which adapt to different light and dark environments and work alternately. When you enter a brightly lit room from the outside at night, or go outside from a bright room, your eyes often can't see for a few seconds, just because two kinds of visual cells are changing their duties. Sometimes, when the light and shade suddenly alternate, people will feel uncomfortable and there will be some disorder in the neural regulation system. Especially in the dark environment, people's pupils are wide open and can't be closed when they encounter strong light. A large amount of strong light entering the eyes will make the retinal nerves feel tired quickly, which will easily lead to decreased vision.
Too strong light is also a kind of pollution, and too messy light is also a kind of pollution, such as all kinds of colored lights rotating in hotel ballroom and stage. Although their light is not strong, it is easy to cause visual fatigue, which in turn leads to brain fatigue and dizziness and headache due to flashing lights. People often say that they feel "dazzled" and "dizzy" in this situation, which refers to this effect. Working in an environment with flashing lights for a long time or frequenting dance halls will affect people's vision, and even lead to a certain degree of vision decline.
5. Light pollution caused by laser and its harm
There is also a special kind of light pollution that has only appeared in recent years, that is, laser pollution, which will directly harm the fundus. In recent years, lasers have been widely used, and even holiday decorations, stage and ballroom arrangements have adopted laser devices, and lasers can be seen everywhere, which is in great danger of flooding.
Laser is a kind of high-energy radiation with good directivity, pure color, high energy and high density. Its density is usually hundreds or even hundreds of millions of times higher than the sun's rays. It can drill holes in metals, drill holes in diamonds and directly weld the most difficult metals together. Even the weakest laser beam generates hundreds of times as much heat as the strong sunlight. Once the laser beam enters the human eye, the lens will converge, but the light intensity will increase hundreds or even tens of thousands of times, and the fundus cells will be burned. There is also a part of the laser spectrum in the frequency range of ultraviolet and infrared rays. Because it is invisible to the human eye, it is more likely to fall into the human eye and cause harm. High-power laser can even directly enter the human body, endangering deep tissues and nervous system.
Third, thinking and discussion on the construction of urban "night landscape"
The hidden pollution caused by colorful neon lights is rarely detected, but the harm exists. It is necessary to formulate technical standards for landscape lighting as soon as possible. More and more cities in China have colorful night scenes. However, night lighting not only beautifies the city, but also brings some adverse effects to the life of urbanites. There are no stars over the city, harsh lights make people nervous, and artificial sunlight makes it difficult to sleep. Urban construction and environmental protection experts remind that while the city lights up, with light pollution, the practice of "only pursuing brightness, the brighter the better" will bring unpredictable harm.
Dr. Lv Bin from Peking University Urban Planning and Design Center said that in recent years, the construction of "night landscape" in China has developed very rapidly. Generally speaking, it is worthy of recognition to make the city bright and beautiful, but in terms of energy and environment, night landscape construction must also be moderate, otherwise the effect will be counterproductive. The main function of night lighting is lighting, followed by beautification. Lighting has a certain light intensity, too bright will interfere with vehicles and pedestrians; Beautifying the night scene requires soft and warm lights. If it is too exciting and makes people feel uncomfortable, it will not achieve the beautification effect.
Recently, the construction of "bright streets" has sprung up in some cities. Bright streets are being built everywhere, whether in business or living areas, so Dr. Lu thinks there is something worth discussing. Night lighting should be designed as required, not to make everything bright, the brighter the better. The bustling business district can properly light up the whole street, but the living area is unnecessary. Just illuminate where it should be. Everyone is very bright, too bright, but people have lost their quiet space. Dr Lu has visited world-famous cities that never sleep, such as Tokyo, Paris and new york. It is rare to see the whole street lit up.
The hidden pollution caused by lighting is rarely noticed, but the harm exists. Staying in a colorful lighting environment for a long time, people will feel psychological and emotional impact more or less. Of course, once people feel uncomfortable, they can choose to leave, but if the lights surround their lives and residential areas, they can't escape. A survey abroad shows that night lighting affects people's normal biological rhythm, making it difficult for people to fall asleep at night and even insomnia. At the same time, improper lighting settings are more harmful to traffic, and the accident rate will increase accordingly.
Professor Li Jingjing of China Institute of Building Research has been engaged in outdoor lighting research for many years, and has long noticed the possible light pollution caused by urban night scene construction. He wrote the paper "Problems and Countermeasures Brought by Urban Night Lighting", and also reminded people on many occasions to be alert to the adverse effects of night lighting. Professor Li said that the role of night lighting in beautifying the city and enriching nightlife is well known, but the light pollution and light interference that followed did not attract people's attention. In fact, night lighting itself has advantages and disadvantages, just like two sides of a coin. It is impossible to completely eliminate the disadvantages, but it can be minimized. Night lighting has two negative effects: light pollution and light interference. The main performance is that it affects normal astronomical observation, interferes with people's normal work, life and rest, and damages people's ability to observe objects.
Professor Li said that developed countries have already learned lessons in this regard. In the 1970s, some people in California, USA, estimated the harm of urban night lighting, and thought that the night brightness over the city would increase by 30% every year, which would make the Observatory lose its normal observation ability. A social survey conducted in Germany once showed that two-thirds of people thought that "artificial sunlight" affected their health, and 84% reported that it interfered with their sleep. These countries have carried out a lot of investigation and research work, published many technical documents to prevent light pollution, and taken measures to reduce the public hazards of light pollution.
Few people in our country realize the harm of light pollution, so there is no unified standard in this respect. Professor Li believes that with the rapid development of urban night landscape construction in China, it is necessary to formulate technical standards for landscape lighting as soon as possible. Let's not take the detour that others have already taken. In addition, he believes that it is also important to strengthen the standardized management of night landscape design and construction. At present, there are few professional technicians engaged in lighting design and construction in China, and many night landscapes that produce light pollution and light interference are caused by unscientific design and construction. It is understood that Tianjin promulgated the "Technical Specification for Urban Night Lighting" last year, which is the first technical specification for night lighting in China. There used to be an "Evaluation Standard for Urban Nightscape Lighting Engineering" for the nightscape construction in Beijing, but only simple items were used to measure light pollution. Experts call for the lack of scientific and normative urban night scene construction, which needs to be changed urgently.
Xinhuanet Los Angeles, August 7 th, citing the investigation report of the American Urban Pollution and Governance Foundation, it released a data that made the world stunned: the light pollution caused by colored lights at night has made one fifth of the people in the world turn a blind eye to the Milky Way! Elvidge, one of the researchers, said: "Many people lost the night sky, and it was our lights that made the night pale. In the night sky far away from the city, you can see more than 2,000 stars, while in big cities you can only see dozens. " He believes that about one-third of the people in the world now live in light pollution. Luo Qingfeng, a Shenzhen native who lives in Zhuzilin, recalled, "Twenty years ago, when I stood on the ground of the city, I could clearly see the Milky Way and the twinkling stars overhead, but now they all disappeared in front of my eyes. I tried my best to see it, but I only saw a few poor stars flickering faintly. " One tenth of the world's population is affected by light pollution, and the night vision ability of eyes is greatly reduced.
According to the students of our school's astronomical team, only a few or a dozen stars can be observed with the naked eye in Shenzhen Pass, and there can be 200-300 stars in second-tier areas with few buildings. In Heyuan and other places, it is easy to see 3000 stars with the naked eye.
Before the war, a study by the Ministry of Culture and the Ministry of Health of the Kuomintang government also showed that light pollution polluted the cornea and iris of human eyes, causing visual fatigue and decreased vision. At present, the myopia rate of senior high school students in China exceeds 60%. Experts believe that the main cause of myopia is the visual environment, not the habit of using eyes.
Yin, director of Shenzhen Lighting Electrical Appliances Association, told this reporter: China's lighting is nearly 50 years behind developed countries, and the light sources that have long been eliminated in other countries are still in use today. Due to the lack of professional designers, most domestic night lighting is not only energy-saving, but also very dazzling, which is easy to make people tired and has a certain gap with international standards.
In fact, the source of light pollution is far wider than we thought for a long time. In addition to the glass curtain wall that people are familiar with in recent years, neon lights, advertising lights, colored light sources in entertainment places, even household lamps, televisions, computers, traditional books, and decorative materials such as glazed tiles and polished marble on buildings will have adverse effects on the human body and the surrounding environment. What's more, even if there is no surplus of the same light sources in life, when their light frequencies are not harmonious, it may also cause light pollution.
At the same time, a single visual environment with strong reflection coefficient will also constitute light pollution. In this environment, it is difficult to reduce the visual stimulation to human eyes, and the visual function will be greatly inhibited. Experts believe that due to the potential harm of light pollution and the lack of definition standards, it has not yet attracted the full attention of society. At the same time, light pollution is difficult to be eliminated or alleviated by decomposition, transformation and dilution like other environmental pollution. Therefore, prevention is the priority.
Lighting system can not only provide people with lighting and beautify the environment, but also become a bright and "gentle" killer of creatures. There will be fewer flies in the center of Moscow this summer. There will also be fewer flies on the main streets of big cities in Russia and other countries. Ecologists are uneasy about this. They know that if the urban environment is harmful to insects, it will also be harmful to birds and other animals-especially people. The results of the survey are surprising: it is not noise or waste gas that kills flies, but excessive or unscientific street lighting and poor quality of lighting lamps. In a word, it is because of "light pollution" to the environment.
In some cases, modern lighting is as harmful as toxic gases and noise. The most serious light damage is the newborn who just came out of the uterus. Once these fetuses are born and stimulated by strong light, their tender eyes will be seriously injured. A survey of 230 newborns in the United States showed that the injury rate of eyes exposed to strong light after birth was 3.6%. If it is premature, most of them will have retinopathy, which will lead to blindness in severe cases. Modern life is inseparable from modern lighting, but people can take various measures to prevent or reduce light pollution. If the lighting is properly adjusted, natural light should be used as much as possible, and sunny rooms should be opened frequently, especially for infants and young children, which should not be exposed to strong light or high-power fluorescent lamps. Also, don't immerse yourself in places with serious light pollution such as dance halls and bars for a long time during entertainment.
"The brighter the better" is the biggest misunderstanding in our country! Xiao, a famous lighting expert from China Institute of Building Science, told the reporter. The urban night lighting project in China has developed rapidly in recent years, and "Let the city light up" has become a very loud slogan. Indeed, the night in the city is much more beautiful than in the past, and even the lighting project can reduce the crime rate and traffic accidents. However, light pollution is ignored by people under the cover of these "auras". In developing cities, misunderstandings such as "brighter and brighter" and "you are brighter than me and I am brighter than you" are common in the construction process.
This increasingly serious light pollution has set a great obstacle for astronomers' observation work. The top of Mount Wilson in California was once a paradise for observers. Hubble, who once changed the history of human astronomical observation, began his great observation here, and Einstein once thought about his great theory of relativity at the observatory here. Wilson Observatory stands in the shade of pine trees at the top of Wilson Mountain. Here astronomers use Hubble telescope to find that the Milky Way galaxy where the earth is located is not the only one in the sky. They found that space is infinitely expanding, and there are countless celestial structures like the Milky Way. This discovery laid the foundation for the later big bang theory. The natural geographical conditions here are the main reason why it occupies an important position in the history of world astronomy-it rises from the ground in a plain, and the airflow from the ocean collides smoothly, so that the glare caused by the atmosphere to the stars is minimized. The smaller the glare, the better the observation results.
Today, Mount Wilson is still a good place for human geography to observe astronomical phenomena, but scientists have encountered new troubles. Although the peak has exceeded the severe smog in Los Angeles, the intensive lighting in the city has greatly affected the observation effect. The noisy and bright Los Angeles prevents them from having a quiet black night sky and quiet twinkling stars.
In southern California, astronomers say they are losing the night sky of observable stars because of light pollution. As early as 1934, Parama Mountain under the dark and clear sky was once the site of an observatory covering an area of 5,600 feet and a telescope with a diameter of 200 inches. Nowadays, the continuous urbanization process has turned the sky in Southern California and San Diego into a "sea of lights". Astronomer Brouca Tu said, "Now the sky is twice as bright as it should be. If the light pollution is tripled, it will take us twice as long to achieve the same observation effect. "