LED Light Bulb

At present, because light extraction efficiency of high power LED with neutral white light (3500-4500) or cool white light (4500-8000K) is generally higher than warm white light (2600-3500K), and most LED road lights adopt an LED with neutral white light or cool white light as their light sources. However, citizens in some cities report that after replacing the traditional high pressure sodium lamps (HPSL) with LED lamps, the road illuminance improves but it is dusky as a whole and makes people feel oppressive and lonely. That is because the human eye is sensitive to light with a 555 nm wavelength. Due to the fact that there is relatively more long wavelength light existing in HPSLs and LED lamps with warm white light, things tend to look brighter than those in neutral white light and cool white light when the light power is the same. What's more, warm white light looks more comfortable and softer and it gives people a feeling of being warm and safe. Moreover, if considere from the point of view of security, yellow light of warm white light are also more suitable than neutral white light or cool white light for road illumination because of their claimed good performance in penetrating fog. Therefore, LED lamps with warm white light are more suitable for road illumination.