I remember when I was a child, in the summer evening in the countryside, cicadas chirped and frogs sounded. When I raised my head, I bumped into the bright stars. Every star radiates light, dark or bright, each has its own charm. The Milky Way with colorful streamers is beautiful and arouses imagination.

When I grew up, and looked up at the sky in the city, I was always obscured by layers of smoke and found that I could not see a few stars. Have all the stars disappeared?

Stars have been around for hundreds of millions of years, and their light has been obscured by the growth of cities because of light pollution.

The trouble of not seeing the stars

As early as 4,300 years ago, ancient Chinese people had already been able to observe the images and time. They could observe the starry sky with the naked eye, thus determining the 24 solar terms.

But as urbanization continues to accelerate, more and more people living in cities are finding that the stars seem to have “fallen” and the brightness of the night is disappearing.

The problem of light pollution was put forward by the international astronomy community in 1930, because outdoor urban lighting makes the sky bright, which has a great negative impact on astronomical observation, also known as “noise and light pollution”, “light damage” and “light interference”, etc., is one of the most widespread forms of pollution in the world, which is easy to be ignored.

In 2013, the increase of the brightness of Chinese city lights became the most serious problem of environmental protection.

Researchers from Italy, Germany, the United States and Israel have now produced the most accurate atlas to date of the effects of light pollution on a planet where more than 80 percent of the population is exposed to artificial light of any kind, and where nearly 80 percent of people in Europe and the United States cannot see the Milky Way.

A third of the world’s population can no longer see the bright stars in the night sky because of light pollution, according to a study published in Science Advances.

An American survey report shows that about 2/3 of the world’s people live in light pollution. Moreover, the pollution caused by artificial light is increasing year by year, with an annual increase of 6% in Germany, 10% in Italy and 12% in Japan.

Classification of light pollution

Colorful night scenes highlight the glamour of urban prosperity, and hidden in this bright world is the subtle light pollution.

Light pollution is a relative concept. It does not mean that reaching an absolute value is light pollution. In daily production and life, a certain amount of light is required to enter the eyes, but beyond a certain range, the excess light makes us feel visual discomfort, and even causes physiological adverse reactions, which is called “light pollution”.

The manifestations of light pollution are different in different time periods, namely glare, interference light and sky escape light.

Glare is mainly caused by sunlight reflected from the glass facade during the day, and at night, by lighting fixtures that interfere with visual tasks. Interference light is light from the sky that reaches the window surface of the living room. And the light from the artificial source, if it goes to the sky, we call it sky astigmatism.

Internationally, light pollution is divided into three categories, namely, white light pollution, artificial day, color light pollution.

White pollution mainly refers to the fact that when the sun shines strongly, the glass curtain wall, glazed brick wall, polished marble and various coatings and other decorations of the buildings in the city reflect the light, which makes the buildings white and dazzling.

Artificial day, refers to the shopping malls, hotels after the fall of night advertising lights, neon lights dazzling, dazzling, some strong light beam even straight into the sky, making the night as day, namely the so-called artificial day.

Color light pollution mainly refers to the black light, rotating light, fluorescent light and flashing color light source installed in entertainment places constitute color light pollution.

* Does light pollution refer to human health?

Light pollution mainly refers to the phenomenon that excessive optical radiation causes adverse effects on human living and production environment, which belongs to light pollution. Light pollution is very common. It exists in every aspect of human life and affects people’s life imperceptibly. Even though light pollution is around people, many people are still unaware of the severity of light pollution and the impact of light pollution on human physical and mental health.

* Damage to the eyes

With the development of urban construction and the progress of science and technology, people almost put themselves in a “strong light and weak color” “artificial visual environment”.

Compared with visible light, infrared pollution can not be seen by the naked eye, it appears in the form of thermal radiation, easy to cause high temperature injury. Infrared ray with wavelength of 7500-13000 angstroms has high transmittance to cornea, which can burn retina and induce cataract. As a kind of electromagnetic wave, ultraviolet rays mostly come from the sun. Long-term exposure to ultraviolet rays will easily cause wrinkles, sunburn, cataracts, skin cancer, visual damage and decreased immunity.

* Interferes with sleep

Although people sleep with their eyes closed, light can still pass through their eyelids and interfere with sleep. According to his clinical statistics, about 5%-6% of insomnia is caused by noise, light and other environmental factors, of which light accounts for about 10%. “When insomnia occurs, the body doesn’t get enough rest, which can lead to deeper health problems.”

* Induce cancer

Studies have linked night shift work to increased rates of breast and prostate cancer.

A 2008 report in the journal International Chronobiology confirms this. Scientists surveyed 147 communities in Israel and found that women with higher levels of light pollution were significantly more likely to develop breast cancer. The reason may be that the unnatural light inhibits the immune system of the human body, affects the production of hormones, the endocrine balance is destroyed and leads to cancer.

* Produce adverse emotions

Studies in animal models have demonstrated that when light is unavoidable, it can have adverse effects on mood and anxiety. If people for a long time under the irradiation of colored lights, its psychological accumulation effect, will also cause fatigue and weakness, dizziness, neurasthenia and other physical and mental diseases to varying degrees.

* How to prevent light pollution?

The prevention and control of light pollution is a social system project, which requires the full participation and joint efforts of the government, manufacturers and individuals.

From an urban planning perspective, lighting ordinances are an important tool for setting reasonable limits on light pollution. Since the effect of artificial light on organisms depends on the intensity of light, spectrum, direction of light (such as direct irradiation of point light source and diffuse of celestial glow), various elements of lighting need to be controlled in the preparation of lighting planning, including the selection of light source, lamps and lighting modes.

Few people in our country realize the harm of light pollution, so there is no unified standard in this respect. It is necessary to set up technical standards of landscape lighting as soon as possible.

In order to meet modern people’s pursuit of high quality lighting, we advocate “healthy light &intelligent lighting”, comprehensively upgrade the lighting environment, and provide humanistic lighting service experience.

What is “healthy Lighting”? That is, a light source close to natural lighting. The light is comfortable and natural, and fully consider the color temperature, brightness, harmony between light and shadow, prevent the harm of blue light (R12), increase the relative energy of red light (R9), create a healthy, safe and comfortable lighting environment, meet people’s psychological emotions, promote physical and mental health.

When humans enjoy the prosperity of the city, it is difficult to escape the ubiquitous light pollution. Human beings should correctly understand the harm of light pollution. They should not only pay attention to their living environment, but also avoid long-term exposure to light pollution environment. Prevention and control of light pollution also need everyone’s joint efforts, really from the source to prevent light pollution.