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In previous articles we talked about different types of lighting these days and delved into the properties of the LED light bulb.
After reading about the merits of the LED light bulb, has this thought ever occurred to you?
‘This LED lighting solution is too good to be true.’
Upon further research, you might have come across articles saying that the LED light bulb emits blue light which causes a myriad of harmful effects including damage to the retina, macular degeneration and disturbed sleep pattern.
Today let’s dispel the myths about blue light once and for all. In addition, we’ll look at what light flicker is, and what it has to do with LED light bulbs.
When there’s white light, there’s blue light too
White light is composed of three coloured lights: red light, blue light and green light. This means that all the white light sources we use in our daily life are also sources of blue light.
Incandescent light bulbs, compact fluorescent light bulbs and LED light bulbs, all produce blue light. But blue light only exists as a small fraction in the wide colour spectrum that natural light gives.
Under normal circumstances, the blue light that LED bulbs give off does not cause much harm to our eyes.
A light bulb’s colour temperature determines the amount of blue light it gives off. Cool white light bulbs emit more blue light than warm white light bulbs. Therefore, for people who are easily affected by blue light, warm white lights are a more comfortable option.
What really is blue light?
LED lighting was not popularised until 2009, since then it has always carried the label ‘harmful to the eyes’.
In 2014, an American open access journal, Environmental Health Perspectives reported that from the outcomes of an experiment on animals, white LED lights are certified to cause harm to the eyes.
The report explained that the LED light source’s high-energy blue light triggered macular degeneration, a kind of pathological change in the eye’s retina. Apart from the journal, health specialists also have written about this discovery.
In reality, blue light is not something invented, made along with the manufacture of LED lights. It is instead a crucial component of natural sunlight, situated in the visible light spectrum’s 400 – 500 nanometer wavelength portion.
Excessive radiation from this portion of the visible light spectrum is what causes harm to the retina.
From the results of experiments done by EU and American laboratories, we can know two things.
One, the blue light content of LED does not exceed that of incandescent light, compact fluorescent light and natural sunlight, given that they are all the same colour temperature.
Two, the amount of blue light optical radiation emitted from a white LED light is similar to the amount emitted from traditional lighting like the compact fluorescent light and the incandescent light. LED lighting is thus a safe lighting product.
LED blue light problem is a thing of the past
In attempt to solve the problem of blue light eye damage, LED manufacturers continually perfect their LED production technology.
After years of modification and evolution, in 2019, the amount of blue light emitted by contemporary LED light has lowered by 80%, compared to earlier LED products.
The European Union has been implementing the ENC62471 which stipulates the evaluation of whether manufactured LED products are photobiologically safe.
Under EU’s standards, safe LED lights which reach the blue light emission standard will be labelled to inform and reassure consumers.
The LED light bulbs you can find on the market are generally safe for your eyes, given that they have undergone laboratory examination.
But since the blue-light-blocking fluorescent coating ages with time, some LED light bulb’s blue light emission might increase over time. Consumers should pay attention to this fact.
How to choose LED light bulbs
Purchase LED lightbulbs from more established brands, and consider the following:
- Warm white lights emit less blue light the cool white ones.
- The higher the colour temperature, the whiter the light is, and the more blue light is emitted. For domestic use, opt for lighting with a lower colour temperature (below 4000K).
- Choose lighting with a colour rendering index (CRI) of above 80Ra. The higher the number, the colour of the objects under the like will be more authentic.
- Choose lighting which complies with the European Union’s standards (EN62471)
What is light flicker?
In general, the type of the lighting’s power source determines whether it will flicker.
Since our mains electricity is an alternating-current (AC) power supply, whose electric current changes direction 50 times a second (50 Hz), lighting connected to an AC power supply switches on and off 50 times a second, causing light flicker.
Human eyes can detect flicker at a frequency below 100 Hz. We can certainly detect LEDs flicker which is at a frequency of 50Hz.
The flickering problem is a real problem to the LED light because unlike the compact fluorescent light and the incandescent light, LEDs have no persistence, meaning that their light output stops and starts instantly as the electric current alternates.
Meanwhile, the flickering problem does not apply to incandescent lights as much because the filament’s residual heat helps it give off light even the power supply switches off and alternates.
The harmful effects of light flicker
Prolonged exposure to light flicker will lead to eye damage, tiredness and mood changes. Effects are especially noticeable in children and migraine sufferers.
According to the U.S. Department of Energy, light flicker at a low frequency might trigger epileptic seizures. Ordinary fluorescent tubes used in office is found to be related to the occurrence of migraines, tiredness, blurry and weakened vision.
In more hazardous scenarios like night driving, light flicker might cause the illusion in which moving objects appear to be still or slowing down.
How to detect light flicker
Turn on the camera function on your phone and aim the lens at the light source.
If you can see the light flashing on your phone screen, it means the light source does flicker.
Truly flicker-free lights are very stable and should not flicker on your phone screen.
The solution: LED transformers
Some LED lights have built-in transformers which convert the power supply for alternating current to direct current. High-quality transformers can even supply a constant direct current to the LEDs. The result is that the light will not flicker visibly.
When purchasing LEDs, opt for the ones with built-in transformers, and only purchase from reliable suppliers.