Making LED bulbs safer: Health and LEDs

[Vanadium 50]

are you saying that if I put a jam jar over my bulb, the wavelengths of light emanating from the jam jar would change.?

I am saying the wavelength distribution would change.

But how do you know that one jam jar is sufficient? Why not two? Why not ten? Why is the bulbe not sufficient? When you decided you were to believe what you want to believe and to heck with science, that's your choice, but part of that choice is that it opens up more questions.

 

[renault]

https://www.edmundoptics.com/c/optical-filters/610/

thanks, this is useful in that now I know that it is possible to produce a notch filter which can eliminate the 'blue spike' outputted from LED bulbs shown to us earlier in this thread (300-400nm.)
So manufacturers could produce bulbs which create this blue light spike at the semiconductor but do not output it from the filter glass enveloping the bulb - and I understand from another contributor to this thread that doing this would mean that we would not have white light but that it would be yellowish. Have I kinda got this right?

 

[f95toli]

Indeed, if your want your source of light to have approximately the same spectrum as daylight you will need quite a bit of blue light included.
Do note that you can't use your eyes to determine colour temperature directly; our eyes adapt based on the light (and surfaces) around us to make things look more or less as they would in daylight. This is why you need to set the colour temperature of your camera* to make the photo look like what you are seeing.

Also, I guess this goes without saying, but there is far, far more UV light in sunlight (with higher energy than in light from LEDs) . If you are worried about the UV in LED light bulbs, you should definitely never spend any time in the sun and at levels we are talking about here probably not even go outside during the day.

*These days most cameras will do an OK job of doing this automatically and the result will usually look similar to what you are perceiving.; but if you want do do it properly you need to calibrate using a grey card (or in the case of a film camera, use the right type of film).

 

[renault]

Indeed, if your want your source of light to have approximately the same spectrum as daylight you will need quite a bit of blue light included.
Do note that you can't use your eyes to determine colour temperature directly; our eyes adapt based on the light (and surfaces) around us to make things look more or less as they would in daylight. This is why you need to set the colour temperature of your camera* to make the photo look like what you are seeing.

Also, I guess this goes without saying, but there is far, far more UV light in sunlight (with higher energy than in light from LEDs) . If you are worried about the UV in LED light bulbs, you should definitely never spend any time in the sun and at levels we are talking about here probably not even go outside during the day.

*These days most cameras will do an OK job of doing this automatically and the result will usually look similar to what you are perceiving.; but if you want do do it properly you need to calibrate using a grey card (or in the case of a film camera, use the right type of film).

thanks, a nice summary. It is not so much that 'I am worried' but generally I take the precautionary principal and if some researchers suggest that current LED's used in the home may cause problems, then I want to consider it. Pinball who posted earlier showed a spectrum from an LED bulb which showed a large spike at around 300-440nm. which he says he has seen in all LED bulbs but it seems that the sun does not produce this spike although it produces 'white' light. I wonder if LED bulbs are unable to produce white light without the 'aid' of this blue spike? - and what the result would be if it were to be filtered out.
I suggest that sunlight is 'pleasant' to us and that the white LED lighting we see in industrial hangars etc leaves one feeling cold and is not a pleasant environment.

 

[hutchphd]

I wonder if LED bulbs are unable to produce white light without the 'aid' of this blue spike?

Google is your friend, unless you prefer to "wonder"....
They sort of mimic fluorescent lights in their optical design. No mercury required, however.

 

[JT Smith]

Pinball who posted earlier showed a spectrum from an LED bulb which showed a large spike at around 300-440nm. which he says he has seen in all LED bulbs but it seems that the sun does not produce this spike although it produces 'white' light.

I'm also mostly uneducated on this subject but what you are saying doesn't seem to be true, at least not in general. Look at these images found with a cursory web search. The first is from LEDs, the second from the sun. The spectrum from sunlight doesn't have a spike but the blue contribution looks to be of similar, if not greater, relative magnitude compared to the orange (at around 600nm).

 

[hutchphd]

They sort of mimic fluorescent lights in their optical design. No mercury required, however.

Is everybody incapable of doing research online?????
The standard "white" LED uses a narrow blue or near-UV LED to excite broadband phosphors which fluoresce to produce the lower energy energy part of the visible spectrum. They produce almost no "far" UV (<200nm): These are energies (>6.2 eV) present in sunlight capable of ionization and causing direct biological harm.
Absent actual good science, I will put my blue blocker glasses on the shelf next to my extensive collection of fashionable aluminum foil hats for indoor apparel.

 

[Drakkith]

The spectrum from sunlight doesn't have a spike but the blue contribution looks to be of similar, if not greater, relative magnitude compared to the orange (at around 600nm).

Indeed. For a 5800 K blackbody, which the Sun closely matches, the spectral radiance is as follows (taken from this website):

350 nm (deep violet): 1.89617e+07 W/m²/sr/µm
400 nm (violet): 2.36154e+07 W/m²/sr/µm
475 nm (blue): 2.6715e+07 W/m²/sr/µm
500 nm (blue-green, Peak emittance): 2.68831e+07 W/m²/sr/µm
550 nm (green): 2.63113e+07 W/m²/sr/µm
600 nm (orange-red): 2.49252e+07 W/m²/sr/µm
650 nm (red): 2.30994e+07 W/m²/sr/µm
700 nm (deep red): 2.1093e+07 W/m²/sr/µm

As you can see, the amount of blue light emitted is quite substantial, very close to the peak radiance. The 450-500 nm band, which is the range we commonly label as blue, would emit more radiation than the red band except that the red band is larger, going from 625-740 nm. The 'spike' in the LED spectrums appears to be necessary for the eye to view them as 'true white'. LED bulbs that are labeled as 'warm white' appear to have a very small or nonexistent spike in the blue region.

I wonder if LED bulbs are unable to produce white light without the 'aid' of this blue spike? - and what the result would be if it were to be filtered out.

They can. Those that lack the blue spike or have a reduced spike are labeled as 'warm white' or something similar and have a yellowish look because of the lack of blue light.

I suggest that sunlight is 'pleasant' to us and that the white LED lighting we see in industrial hangars etc leaves one feeling cold and is not a pleasant environment.

Which is odd, seeing as how a good LED bulb with a 'spike' of blue closely matches the color of the Sun and sunlight (which is white, not yellow or orange as commonly believed). Other than missing the IR light that literally helps warm us, there shouldn't be much difference in the two. Strange, eh?

 

[JT Smith]

Which is odd, seeing as how a good LED bulb with a 'spike' of blue closely matches the color of the Sun and sunlight (which is white, not yellow or orange as commonly believed). Other than missing the IR light that literally helps warm us, there shouldn't be much difference in the two. Strange, eh?

I don't understand how exactly we perceive light but maybe it's due to the missing part of the spectrum compared to the sun? Perhaps the OP should be worried about what's left out with LED lights instead?

We are slowly transitioning to LED lights in our house now that the better ones are close approximations to incandescent and are far better than fluorescent. Our undercounter LED lights are tuneable in color but it's sure not like sunlight; there's no confusing how the two look or make me feel.

 

[Drakkith]

Also remember that this is all subjective. My fiance prefers a 'true white' bulb compared to a 'warm white', as she doesn't like the yellowish lights that many other people do.

 

[JT Smith]

Of course. That's why they sell ones where you can change the color. I'm just saying that I can't set a color that looks natural to me. And significantly, none of the lights "feels" natural. There's a quality to natural light that, to me, just feels better. Maybe my brain is conflating the light with fresh air or open space but I think the light is different in an important way as well.

 

[Motore]

I have warm white and normal white LED bulbs. The normal white feels quite natural. Of course we have LED bulbs now for 5 years and I got used to them. The halogen bulb is just too yellow.
And in now way do LEDs pose any health concern.

 

[f95toli]

Pinball who posted earlier showed a spectrum from an LED bulb which showed a large spike at around 300-440nm. which he says he has seen in all LED bulbs but it seems that the sun does not produce this spike although it produces 'white' light.

And how is that relevant for health effects? A spectra show the distribution of wavelengths, it tells you nothing about intensity. The light outside on a sunny day is way, way more intense than what you get from say a 11W LED, meaning even if the relative amount of blue light is lower than in a LED; the amount of UV you will get exposed to by just being outside is much, much higher.

No one is saying that high energy UV is good for you , it is the main risk factor for skin cancer(use sunscreen and don't use sunbeds). But regular LED bulbs do not produce light at those wavelength, and -as I pointed out above- the intensity of blue light is so low that even if you for reason believe it is a risk factor (which as far as we know it is not); it will be completely negligible compared to just being outside.

 

[renault]

Is everybody incapable of doing research online?????
The standard "white" LED uses a narrow blue or near-UV LED to excite broadband phosphors which fluoresce to produce the lower energy energy part of the visible spectrum. They produce almost no "far" UV (<200nm): These are energies (>6.2 eV) present in sunlight capable of ionization and causing direct biological harm.
Absent actual good science, I will put my blue blocker glasses on the shelf next to my extensive collection of fashionable aluminum foil hats for indoor apparel.

asking questions to learned friendly people on this forum IS part of my research. Nobody is forced to respond.

 

[hutchphd]

Why ask someone to take the trouble to explain something easily understood by a cursory visit to Wikipedia? Seems presumptuous to me.
There actually are interesting questions.

 

[renault]

Why ask someone to take the trouble to explain something easily understood by a cursory visit to Wikipedia? Seems presumptuous to me.
There actually are interesting questions.

I have a level of trust in the responses from the contributors on this forum which I don't have of Wikipedia. If you don't find the questions interesting then perhaps you should not 'take the trouble to explain'.

 

[hutchphd]

My response was prompted by a colloquy which contained a series of incomplete and complicated answers which should, in principle, be very simple.
As a professor I used to say repeatedly "there are no stupid questions"......I will modify this with "but there are lazy ones"

 

[renault]

As a lazy person I say "thank you professor"

 

[JT Smith]

Why ask someone to take the trouble to explain something easily understood by a cursory visit to Wikipedia?

Laziness is one possibility. Another is that it isn't always easy for a given person to parse the information available. Some things you can just look up, others are not as googleable. And even the things that have comprehensive wikipedia pages still require a certain amount understanding. If the person lacks that then they need someone to break it down for them. Think of a little child who needs their food cut into little pieces, maybe even fed to them with a spoon.

A third possibility is that someone simply wants the attention that starting and stoking a thread generates. Or it could be a combination.

I would wager that this particular question is googeable.

 

[hutchphd]

If the person lacks that then they need someone to break it down for them

And if, in fact, the question had been prompted by such an initial search, of course I would have gladly allayed any specific confusion to the best of my ability. But lazy inquiries are seldom followed by any real progress in understanding. One needs to be actively confused first, IMHO. I know I learn much faster when I am actively seeking the answer.

 

[Drakkith]

Let's knock it off with the thinly veiled insults to the OP. Further such posts will likely result in an infraction and deletion of said posts. Virtually any question asked on PF is capable of being answered elsewhere or by sustained study by the person asking the question. But if we held to that standard PF wouldn't exist at all.

 

[JT Smith]

Sorry if my words came across that way. I can't say what the OP's motivation is but I don't think ignorance is a reason for insult. We all are about most things. I can think of a number of topics that I don't understand well enough and many of them are probably beyond my ability to figure out on my own. I just don't have it. In those cases I'd ask and hopefully would be able to figure out who to trust.

 

[hutchphd]

Let's knock it off with the thinly veiled insults to the OP

My intent was not to insult the OP but to aid in educating his or her capability to do fruitful self-directed research. I also believe the explanations available elsewhwere would likely be more edifying than some of the responses being engendered. Graphs and color pictures and layout are important, particularly for optics and ad hoc advice about physics is not always a good idea. There were no thinly veiled insults intended. I said what I meant and meant what I said.

 

[Drakkith]

The OP has already explained that they trust us more than they trust wikipedia and possibly other sources (and/or perhaps more than they trust their ability to interpret and understand the information presented in those sources), so discussion of why the OP did or didn't refer to some other reference is unwarranted in my opinion. Anyone wanting to discuss this further can send me a PM, but I ask that you keep it out of the thread from now on.

 

[renault]

Can anyone suggest how the LED bulbs with variable colour temperature work?
I can only assume that the only practical variable which could change this would be modification of the supply voltage.

 

[Motore]

They have multiple LEDs with different colors and adjust the intensity between them with a micro controller.

 

[Mendrys]

LED bulbs create the different colors/temperatures of light by using varying intensities if 3 separate LED elements inside them, green, red and blue. That is how they can be adjusted to almost any color we can perceive. Some are hard tuned to a specific color, or temperature, for those that are meant to replace conventional bulbs. Others can be adjusted to a wide range colors via Bluetooth for example. Efficient blue LEDs were long sought for a variety of reasons, energy efficient indoor lighting being one of them, and the inventors of efficient blue LEDS received the Nobel prize as it was such a huge benefit.

https://www.nobelprize.org/uploads/2018/06/popular-physicsprize2014-1.pdf

I agree that it may be a good idea to limit your exposure to "bluer" light at times, especially at night in the hours before bedtime as it suppresses the release of melatonin that can decrease the quality of your sleep. However, It's probably more beneficial at other times since it also increased your awareness and lowers your reaction times.

 

[renault]

thank you all for your contributions on this post. I have learnt a lot. I started with the thought that all LED lighting was bad except for its low energy usage. I am now not so anti LED although imo the illumination it produces is not pleasing to the eye to say the least - even the so called 'warm' bulbs. I fear that the current state of our worldly thinking cajoles us to accept 'developments' which are inferior in many ways - but have an advantage in one area - like LED bulbs; they use less energy but are poorer than incandescents in other qualities however they are promoted without question - rather like wifi in the home instead of ethernet, mobile phones instead of landlines and electric cars instead of IC cars.
Thanks again

 

[hutchphd]

One other way that LED lights differ from incandescent bulbs is that LED emissions have a very short "time constant" They can be modulated at nearly 100 MHz (I have actually designed circuits to do this for time resolved/phase resolved fluorescence experiments). I believe that rapidly pulsating light could be far more deleterious to our nervous systrem than simply blue light. In fact, for a white LED, and depending upon the power source, the blue light could be modulated while the phosphor response could be slow and hence barely modulated. This might produce untoward effects in some people. This is clearly a personal theory (since I just dreamed it up) and therefore verboten here but I believe I will look into this interesting question.......with thanks to @renault

 

[Drakkith]

I am now not so anti LED although imo the illumination it produces is not pleasing to the eye to say the least - even the so called 'warm' bulbs. I fear that the current state of our worldly thinking cajoles us to accept 'developments' which are inferior in many ways -

That's entirely your opinion. I greatly prefer LED bulbs compared to incandescent. In my opinion almost everything about them is superior for indoor, house lighting. Less power usage, less heat produced, longer lifespan, and superior light quality. The only drawback compared to incandescent bulbs that I can think of are their increased price. But since they last much, much longer and use far less energy that's not really an issue for me.

but have an advantage in one area - like LED bulbs; they use less energy but are poorer than incandescents in other qualities however they are promoted without question - rather like wifi in the home instead of ethernet, mobile phones instead of landlines and electric cars instead of IC cars.

I'm not sure what 'promote without question' is supposed to mean here. With the exception of electric cars, everything you mentioned gained its popularity because the consumer greatly preferred it over the existing products. Wifi untethers you from a physical cable and makes portable devices capable of using the internet possible, while mobile/cell phones had the same effect (and more) compared to landline phones.

 

[sophiecentaur]

The only way people can function is:

1. Trust that mainstream science and medicine is generally correct.
or
2. Distrust mainstream science and medicine, but simply pick and choose what health issue they're going to get scared about and change in their lives since you literally cannot keep up with all the issues that crop up.

I choose to do number one and trust that modern medicine is generally correct and even when they are wrong they will tend to correct themselves over time.

If you add the caveat about using your intelligence and existing knowledge then I'd definitely agree If you distrust mainstream science then you are totally out on your own.. You have to make individual judgements about every new idea that surfaces and the sort of person who distrusts mainstream science has to mistrust everything that's written.

I tend to take your number 2 option, being guided by the 'follow the money' principal and generally what I see around me

Option 2 requires you to question the science that produced the computer you are using at this minute and allowed the James webb telescope project and others. Where would you stop? Anti vaxers and climate denyers can't be trusted either and it is their ilk that are responsible for many of the 'bad things' that are with us today. Science may not be perfect but it can be dodified along the way and it's obviously the least worst path to follow. Following the money is not to judge the Science but justifiably to judge the morals of your fellow humans; you should not throw the baby out with the bathwater. (look it up if you are not familiar with the idiom)

 

[renault]

One other way that LED lights differ from incandescent bulbs is that LED emissions have a very short "time constant" They can be modulated at nearly 100 MHz (I have actually designed circuits to do this for time resolved/phase resolved fluorescence experiments). I believe that rapidly pulsating light could be far more deleterious to our nervous systrem than simply blue light. In fact, for a white LED, and depending upon the power source, the blue light could be modulated while the phosphor response could be slow and hence barely modulated. This might produce untoward effects in some people. This is clearly a personal theory (since I just dreamed it up) and therefore verboten here but I believe I will look into this interesting question.......with thanks to @renault

yes perhaps a little like some commentators have suggested with so called SMART meters. Their reporting data is modulated along the 240V. a.c. mains cables within the property and it is suggested that this can be harmful. Here at home I do not use wifi but I use a so called powerline ethernet where the data is superimposed over the mains supply. I have heard that this can be problematic too. Problems with pulsing or something like that.

 

[renault]

I bought a couple of LED bulbs yesterday, both rated at 4W. One stated to be 470 Lumen / 2,700°K and the other 180 Lumen / 1,800°K. I put one in each of my identical bedside lamps and the difference is enormous.
My first reaction was that the 1,800°K. bulb was so yellow and dim (of course) however within just a few minutes I detested the 'quality' of the 2,700°K. lamp. I cannot say why but I did not want to look in its direction. I read without difficulty my book as usual even though the light was yellow and dim. Not very scientific I know, but an observation all the same.

 

[renault]

If you add the caveat about using your intelligence and existing knowledge then I'd definitely agree If you distrust mainstream science then you are totally out on your own.. You have to make individual judgements about every new idea that surfaces and the sort of person who distrusts mainstream science has to mistrust everything that's written.

Option 2 requires you to question the science that produced the computer you are using at this minute and allowed the James webb telescope project and others. Where would you stop? Anti vaxers and climate denyers can't be trusted either and it is their ilk that are responsible for many of the 'bad things' that are with us today. Science may not be perfect but it can be dodified along the way and it's obviously the least worst path to follow. Following the money is not to judge the Science but justifiably to judge the morals of your fellow humans; you should not throw the baby out with the bathwater. (look it up if you are not familiar with the idiom)

I don't think this thread is the right one to enter a discussion about your comment. I could count myself as both of those although the terms would need very much refining. If you would like to discuss them, please open a thread.

Anti vaxers and climate denyers can't be trusted

 

[Drakkith]

yes perhaps a little like some commentators have suggested with so called SMART meters. Their reporting data is modulated along the 240V. a.c. mains cables within the property and it is suggested that this can be harmful.

That is extremely unlikely, and, I suspect, entirely unsupported by evidence.

I bought a couple of LED bulbs yesterday, both rated at 4W. One stated to be 470 Lumen / 2,700°K and the other 180 Lumen / 1,800°K. I put one in each of my identical bedside lamps and the difference is enormous.
My first reaction was that the 1,800°K. bulb was so yellow and dim (of course) however within just a few minutes I detested the 'quality' of the 2,700°K. lamp. I cannot say why but I did not want to look in its direction. I read without difficulty my book as usual even though the light was yellow and dim. Not very scientific I know, but an observation all the same.

You are free to use whichever lights you prefer.