Blue light: Consequences for visual health and photobiological risk
What we define as visible light refers to electromagnetic emissions within a specific wavelength range, namely emissions between 380 and 760 nanometres. The shortest wavelengths are the blue tones, while, at the opposite end, we have the warmest tones, even red ones.
Blue light ranges fulfil very important functions, such as helping us to differentiate colours through correct chromatic reproduction and saturation. They also help us to regulate circadian rhythms - which depend on the night-day cycle - in a very specific emission that stimulates the intrinsically photosensitive ganglion cells (ipRGC), 480 nm. (You can find out more about how lighting influences people's well-being in this article).
Sunlight, due to its continuous spectrum, contains a certain amount of blue light, which varies depending on its intensity and brightness throughout the day. We can also find these emissions in artificial light sources, such as LED technology, or the light emitted by TV screens, computers, and mobile devices.
However, overexposure to this type of light can have negative consequences for our health - known as photobiological risk. This is especially the case in children and the elderly, who have more difficulty filtering out shortwave light. For this reason, standards and regulations are in place to assess and regulate blue light emissions from luminaires, and there are also lighting solutions that can reduce high blue light intensities.
What is blue light?
We can categorize the so-called blue light hazard as being the wavelengths between 380 nm and 500 nm. On this part of the spectrum, high emission occurs, which is called high-energy visible light (HEV Light), and it corresponds to the blue/violet and blue light spectrum. Before we reach this area of the spectrum, which is when the blue light starts to become visible (with shorter wavelengths) we find the famous ultraviolet (UV) rays.
In a natural environment, blue light is associated with a high-radiance (intensity) light source, such as when we look directly at the sun or a welding light.
LED lighting has no ultraviolet radiation, but it does contain a high concentration of blue light. In fact, a typical white LED works on the basis of a chip that produces high emissions of blue light, and several layers of multiple phosphors that allow longer wavelengths to be produced.
Consequences of blue light for eye health
The consequences of blue light on human health are still under investigation. For the time being, the main conclusion is that, in general, blue light is harmful if we are exposed to it intensely and for long periods of time.
In these cases, according to ophthalmology specialists, blue light can cause photochemical damage to the retina that may eventually be linked to diseases such as age-related macular degeneration (AMD), which is common in people over 60 and causes vision loss or blurred vision.
Similarly, blue light can cause photothermal damage, similar to the damage caused by UV, but at a much lower level. One such example of this damage is skin ageing. It should be stressed, however, that we are talking here about the consequences of prolonged exposure to intense blue light.
The International Commission on Illumination (CIE from its French title) published a statement in 2019 to state its position on the risks of blue light. They argue that the term blue light hazard should only be used when talking about the photochemical risk to retinal tissues associated with looking directly at bright light sources. According to the CIE, although blue light can be uncomfortable to the eye and cause stress, "there is no evidence of any adverse health effects in humans from occasional exposure to optical radiation at the exposure limits quoted"; these limits are set out in IEC/CIE 62471:2006.
The ICN and other experts also draw attention to children's exposure to blue light. The retina of a child under 14 is not yet fully developed and, as with older people, who tend to lose visual acuity with age, they have difficulty filtering out blue light waves. Because of this, it is recommended that blue light exposure values be reduced by 10 nm for children.
For this reason, it is especially important to have appropriate lighting solutions in order to reduce harmful emissions and avoid prolonged exposure to blue light, especially in settings and workspaces intended for sensitive users. This becomes a key issue when considering lighting for educational areas, hospitals, nursing homes, as well as any other area or workspace where users stay for prolonged periods of time, such as in offices.
Photobiological risk: What is it?
Photobiological risk refers to the possible adverse consequences of light radiation on the skin and eyes. This photochemical damage to the retina will depend on the technology used and the exposure in terms of time and intensity to which we are exposed to this light. For this reason, we must consider the lighting requirements focused on people's visual health, as set out in the EN 62471 standard.
Blue light risk assessment regulation
The IEC 62471 standard issued by the International Electrotechnical Commission (IEC) specifies the method for assessing the risk of blue light in light sources and luminaires. On the basis of this standard, the product can then be classified according to its risk. In each of the categories, it specifies the exposure limit which would pose no photobiological risk. This classification divides luminaires into four groups: Group 0 (No risk), Group 1 (Low risk), Group 2 (Moderate risk), and Group 3 (High risk).
Lighting solutions to improve visual health
In order to ensure optimum comfort and improve areas with regard to visual health, it is essential to choose lighting solutions to illuminate specific spaces by addressing three key aspects:
- Technological choice
- Visual comfort
- Lighting quality
For this reason, Lamp has included its LED Well-Being Technology in its technological range of lighting solutions. This has been integrated into many of our luminaires, and its main characteristic is the reduction of blue light emissions found in the 450 nm wavelength - the most harmful. At the same time, it optimizes emissions around 480 nm, those that improve circadian stimulation and the synchronization of our biorhythms. In turn, this technology has an excellent colour rendering - higher than 97 - and an R9 higher than 80. It is an ideal technological choice for applications that seek the highest requirements in terms of people's well-being.
It is also necessary to manage glare levels through proper shielding, as in the case of the Ocult linear downlight, and different optical solutions such as the Opal Confort diffuser or Tech ultra-comfort reflectors developed by Lamp for different families such as Fil 45, Fil 35 or Lamptub 60, as well as the integration of optics in our ranges of downlights such as Kombic 100 and Kombic 150, which minimise glare through proper lighting control. Finally, luminaires classified as RG0 - free of photobiological risk - become great assets for lighting spaces that focus on people's health and well-being, thus helping to prevent fatigue and visual stress, in addition to the potential risks mentioned above.