Recently, research teams in Italy and the United States published a research report in the American Science Journal. The report shows that the problem of "light pollution" caused by excess artificial light such as nighttime illumination makes it impossible for one in every three people in the world to see the starry sky. Fabio Falki of the Italian Institute of Light Pollution Science and Technology said: "Now most countries use LED lighting. We should carefully consider the color and lighting level of LEDs. On a clear night, this pollution will appear 2- Three times the increase." When this news came out, it caused many people to discuss. Is it really the light pollution caused by LED? The reporter immediately called the founder of Minghua Pu Yongming, the strongest design workshop in the domestic LED street lamp industry. Mr. Chen Kai, President. He said: the city's main lighting fixtures or street lights can cause direct pollution of urban nighttime light and urban street lights, but it means light pollution caused by LED lighting. Because the current main lighting of the city is still mainly applied to traditional high-pressure sodium lighting, almost no replacement into LED, the replacement rate in China is relatively high, may be 5-10%, but the global replacement LED lighting level is less than 1% . Therefore, the "culprit" that causes nighttime light pollution in cities should be high-pressure sodium lamps that have long been used on a large scale. Urban lighting lamps have a large amount of sodium yellow light. This kind of light penetration is strong, coupled with the city's flashing commercial neon lights and crane tower glare, the impact on astronomical observations is basically devastating. Why does the sodium lamp cause nighttime light pollution in the city? Chen Kai said: "Because the sodium lamp is yellow light and the LED lamp is white light, from a spectral point of view, LED white light is not easily diffused in the air, and yellow and red light are easy to be in the air. Diffuse reflection in the middle. Because the light distribution of the sodium lamp is chaotic, it has upward luminous flux, and the LED lamp is accurate light distribution, wherever there is light, there is no need for light. Only the required area of the LED street lamp is There is light. Therefore, the light of the general LED street light is irradiated on the road surface, while the traditional light source sodium light is scattered everywhere, the waste is very serious, and all the wasted light will eventually become light pollution. Therefore, LED lighting is the future elimination. An effective way to pollute the city at night."