The yellow street lamp reflects soft light on the stone building. Most of Chicago's streetlights, alleys and parks are hazy orange because of their iconic yellow streetlights. In the past two years, more modern LED lamps are slowly replacing warm tone high-pressure sodium lamps.
The high-pressure sodium lamp, which uses metal sodium vapor as working material, has high luminous efficiency and strong fog permeability, and is widely used in roads, highways, gymnasiums and other places. But there are not many cities like Chicago where all the streets are covered with yellow streetlights. In the 1970s, when the place was just installed with high-pressure sodium lamps, critics said that they turned the streets into nightmares, but now it has become a unique warm color of the crime city of Chicago. Especially when people look at the night scene of the city of Chicago on the plane, they will find that there is no cold light in it.
Intelligent lighting plans are changing the status quo. In the past few years, more than 270000 high-pressure sodium lamps in Chicago have been converted into more energy-efficient LED lamps. It's equivalent to saving 70 million kilowatt hours of energy, which is about 3.4 million dollars.
But in addition to the visual effects that may be emotionally unacceptable to some citizens, is this kind of replacement only beneficial? Not necessarily. Studies have suggested that Chicago's new streetlight brightness, because it contains more blue light, will have an impact on Residents' health, local wildlife, and even crime rate.
Professor Martin orbey, a Canadian physicist and light pollution researcher, said that compared with the old non LED lights they are replacing, the LED lights being installed in Chicago can actually slightly reduce light pollution, but the problem is that the light temperature of the new bulb is 3000 Kelvin, a unit used to measure light temperature. The higher the value, the more blue light. Using 2200 Kelvin LEDs would reduce light pollution in Chicago to "at least 50 percent" of its current level, he said.
The city is seeking guidance from experts from the U.S. Department of energy, the American Medical Association and the illuminating engineering society to determine a safe color temperature, as there are studies linking outdoor blue light with cancer risk and reducing melatonin.
Chicago police believe that brighter streets can reduce crime. But some conflicting studies show that brightness seems to have no direct relationship with crime rates. Later, they revised their argument that the new light bulb could provide a better view of police cameras, thus indirectly reducing crime.
The city's ultimate goal is to save $100 million on roads and replace 270000 lights in the city by 2021. Not only is the LED low power consumption, the number of times it needs to be replaced will be reduced. An automated system provides support behind the scenes, telling staff when and where to replace street lights