The possible blue light hazards in LEDs on the eyes have become a hot global topic. The expanding application field for LED lighting has raised consumer awareness towards the possible risks of blue LEDs. In order to clarify the consumers misgivings towards LED lighting products, the China National Lighting Fitting Quality Supervision Testing Center (CLTC) has released a report addressing the dangers of blue lights in LEDs. The CLTC advises that single LED package components with 1W power must strengthen structural protection measures and that color temperature for indoor lighting must not surpass 4000K.
CLTC pointed out that the danger of blue light is not only present in LEDs, during the 20th Annual Cross-Strait Lighting Technology and Marketing Seminar. Metal halide lamps and certain florescent lamps also have concerns towards blue light risks in the past. Blue light is important in the formation of white light. White light cannot exist without blue light. Usage, product quality, and degree of safety are all highly related.
The difference between blue light hazards and overexposure
The blue light hazards created by LED lighting products have caused the market to go into shock when the word “blue” is mentioned. The definition of blue light hazard according to CLTC is that when radiance standards reach group 2 or 3, the eye can be injured in a short period of time. Group 2 and 3 are categorized as moderate risk (group 2) and high risk (group 3). For group 2, radiance reaches ≤4×106W•m-2•sr-1 and luminaries will not cause dangers from unsuitable glare or color temperature. Group 3 luminaires has a radiance of ≤4×106W•m-2•sr-1 and can cause instant damage.
The difference between blue light overexposure and blue light hazards as explained by the CLTC is that the “overexposure” of light towards human physiology goes unnoticed for months or even years before the effects on the circadian rhythm are apparent. However, there is currently no corresponding assessment standard.
How to avoid the effects of blue light hazards and overexposure
According to a survey by CLTC, through random sampling, one product placed under abnormal condition tests reached risk group 2. A single LED component in this product had a power level of 1W. This type of LED package has high lumens per area. If one is to stare directly at this type of light source, their eyes could be exposed to blue light hazard. Therefore, it is advised that use of 1W LED package components must use a diffusion cover or similar structural protection measures, as well as warning labels.
Additionally, the quality of phosphor coating on blue LED chips is also a huge factor to its effects on health. The poor quality of phosphor allocation and coating for LED products from unclear backgrounds can reach color temperatures as high as 6500K and even 100,000K. Long term use of this type of product can have effect on one’s circadian rhythm. Overexposure can affect sleep, circadian rhythm, as well as weaken the immune system.
CLTC therefore advises that in order to avoid the effects on one’s health from long term exposure to high color temperature LED lightings, indoor lighting should not surpass a color temperature of 4000K and color rendering index to be no less than 80.
