Cities around the world are using LED street lights to replace the original high-pressure sodium lamps, and there are more choices for the color of street lights. High-pressure sodium lamps can only emit warm yellow light, while the color of LED street lights can be customized for specific needs. Most LED street lights emit white light, and only a few are designed to emit blue light. An increasing number of cities have implemented blue street lights in recent years. In this article, we will introduce blue street lights and explain why many cities use them.
What is a blue street light (LED)?
If a street lamp emits blue light, we can call it a blue-light street lamp. Street lights come in a variety of forms, and we may group them based on the kind of light each one emits. For instance, because they emit yellow light, HPS lamps are considered yellow street lights. Most LED street lamps are white light street lamps.
Why do some cities use blue street lights?
Although there are blue street lights in some cities, they are not very common. Some cities install blue street lights to improve driving safety, reduce crime, or improve the city’s view, while more cities install blue street lights because they bought low-quality LED street lights. After using these street lights for a period of time, the light of the street lights turns blue or purple. We will analyze the reasons for installing blue street lights in the following paragraphs:
1. Improving driving safety
When driving for a long time or at night, the driver’s eyes are prone to fatigue and dryness. Blue light can relieve eye fatigue, making the driver more comfortable and focused. In addition, blue lights can also improve drivers’ alertness and reaction speed, which is helpful for avoiding traffic accidents. Blue light can also keep people calm because it is soothing psychologically. When driving at night, drivers may face various pressures and tensions. The blue light helps them maintain a peaceful state of mind and improve driving safety. Blue lighting is not only used in residential areas and railway stations, but also in some accident-prone areas, such as highways, to reduce traffic accidents.
2. Representing a special meaning
The manager may give priority to blue street lamps to make the whole city look more beautiful and enhance the image of the city.
Some areas will also use blue lighting for commemorative purposes. For example, in order to commemorate a great doctor, a place will use blue lighting in the area where he works; in this way, people will permanently remember the deeds of this doctor.
3. Reducing crime rates
Blue street lights can divert the attention of criminals or those who intend to commit suicide, calm them down, and reduce this kind of behavior.
Under the blue light, it will be more difficult for people to see their veins, which makes it more difficult for them to inject drugs, thus reducing the abuse of drugs.
Blue-light street lights will also make pedestrians more alert because the roads will become more visible. People can see things far away and have enough time to react before danger comes.
According to news reports, after using blue light street lights in Nara, Japan, the crime rate decreased by 9%, and after the Osaka Metro Company used blue street lighting, the number of suicides decreased by 84%. Now many Japanese train stations and bridges are using blue street lighting.
4. Protecting animals
Blue light has little impact on animals. The blue street lights protect insects, such as mosquitoes and moths, because they will not fly to the lamps in groups at night. This will also keep the street lamp clean and bright.
5. Environmental protection
Blue light is easy to scatter, and it has a short wavelength. Additionally, plants are better at absorbing blue light, which lessens the negative effects of light pollution on the environment and creatures that live nearby.
6. Using low-quality street lights
There are two ways for LED street lights to emit white or yellow light. One is to use multiple lamp beads in the light source, which can emit red, green, and blue light, and achieve white or yellow light by adjusting the proportion of these three types of light. The other is using blue light as the light source and then applying phosphor to the lamp. When blue light from the LED light passes through the phosphor coating, some of the blue light is absorbed by the phosphor. Then, the blue light combines with the red and yellow light emitted by the phosphor to create white light.
The cost of using phosphors is lower than that of using three colors of light. If the purchasing department does not distinguish carefully, they may buy low-cost street lights using phosphors. With the use of street lights, the vibration from the road will cause the phosphor to slowly fall off, and the color of the street lamp will gradually turn purple and blue. When purchasing street lights, it is necessary to know more about the relevant parameters of the street lights and the reputation of the manufacturer. Finding relevant institutions to verify the products is also helpful to find high-quality street lights.
Negative effects of blue street lights on the human body
Science shows that blue light may be harmful to the human body, and many cities have thus banned these lights. There are very few cities that install blue street lights because of the following influence:
- 1. Increasing visual fatigue
Blue light will make people more focused, and the focus of blue light will fall a little forward of the retina. If the streets use blue street lights, people’s eyes won’t be relaxed for a long time, which will accelerate visual fatigue. Adding a section of blue street lights to the highway can attract the driver’s attention, but using them on the entire highway will make the driver feel stressed.
- 2. Harmful tothe eyes
Blue light has a short wavelength and high frequency and can shine directly on the retina, which will accelerate the oxidation process of the macular area of our eyes. As a result, our vision will decrease, and we may suffer from maculopathy and cataracts. Luckily, the light of blue street lights rarely shines directly on people’s eyes but will reflect. The energy of light is greatly reduced, so the damage to the eyes from blue-light street lights is very limited.
- Affecting sleep
Blue light will inhibit the secretion of melatonin in the human body, which will make people have poor sleep quality or even be unable to sleep. Therefore, the light distribution of blue street lamps must be scientific. The light should emit on the ground instead of spreading around, and such street lamps should not be installed in residential areas in case they disturb the lives of the nearby residents.
Summary
In general, there are very few areas that use blue street lamps for night lighting. Researchers are inventing LED lights that emit mild blue light that does not harm the human body. These lights minimize the influence on people’s health and allow citizens to enjoy the beautiful night view.
