Are Blue LEDs bad for peoples eyes? - Page 1
Forum section: electronics / general

author: ocset
author_rank: Super Contributor
timestamp: June 10, 2017, 11:11:45 pm
content: Blue LEDs are bad for youHello,We have just nearly won a contract to supply color changing LED lamps to the local park.However, the local council have said that since blue is one of the colors…..we must first prove to them that the brightness of the blue phase is not enough to damage peoples eyes. They want us to provide a math calculation showing the nearest possible distance to someone’s eyes, and then prove that our lamp will always keep the blue phase dim enough not to damage peoples eyes. It seems ridiculous. Surely Blue Light isn’t any more of a danger to eyes than any other color?All you can find on the web is trash stories like this…http://metro.co.uk/2013/12/09/led-lights-should-we-worry-about-damage-to-our-eyes-4220937/

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: June 10, 2017, 11:49:35 pm
content: bad google fu - or did you really just not want to find anything?if you try you should find serious articles on bad LED street lighting - direct eye damage not likely but several health, safety and environmental factors should go into the lighting designtoo much blue, wrong wavelength will make for excessive iris response - leaving the drivers, walkers potentially "night blind" when leaving the overlit, too blue, too high color temperature blockmelatonin levels, circadian rhythms can be disruptedand there should be timed, seasonally appropriate turn downideally even the color should be adjustable - but tri LED color is more expensive than blue and phosphor "white" LEDsmy city is putting in just such too blue, too bright street lighting and I hate itmany have complained to the city manager now that they are installed and no one is going to replace them for a decade or morea company really should care about its ultimate customer's long term satisfaction with its products

author: Someone
author_rank: Super Contributor
timestamp: June 11, 2017, 12:00:11 am
content: Quote from: treez on June 10, 2017, 11:11:45 pmWow, how can you operate a company bidding for public tenders when you don't understand the fundamental safety requirements of the industry?https://en.wikipedia.org/wiki/High-energy_visible_lighthttp://www.cree.com/led-components/media/documents/XLamp_EyeSafety.pdfEven when presented with the questioning you still couldn't find the relevant information.Cowboys like you should be revealed for the frauds you are.

author: CopperCone
author_rank: Super Contributor
timestamp: June 11, 2017, 12:12:27 am
content: i wonder what effect it has on crack heads, it might make people angrier and increase crime.

author: floobydust
author_rank: Super Contributor
timestamp: June 11, 2017, 12:58:32 am
content: "Retinal Photochemical hazard (380 nm – 550 nm)Photochemical damage region, or blue-light hazard region, is themost hazardous part of the spectrum since damage can occur at exposure levels similar to natural light.[1,2]. Over-exposure to this spectral range is attributed as solar blindness or welder’s flash, and can lead to scotoma. Photochemical damage follows the reciprocity rule for exposure time and intensity and is thus separated into two types: Type I results from long-term, low-intensity exposure where damage is due to constant photobleaching; Type II results from intense, short-term exposure"http://orm.uottawa.ca/programs/em-radiation-safety/photobiological-effects"... To date, the testing shows that Cree’s blue and royal blue LED components (450-485 nm dominant wavelengths) pose a higher potential eye safety hazard than its white LED components. Other colors of LED components, such as green and red LED components, do not pose as significant of an eye safety risk. ..."

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2017, 01:39:17 am
content: Quote from: Someone on June 11, 2017, 12:00:11 amHow is he a fraud? He's asking a question.Using those Cree Blue leds what do you think would be an unsafe level of lux?If you don't want to tell him that is fine but let me know if you think it is possible he could even generate that as a street light.

author: Someone
author_rank: Super Contributor
timestamp: June 11, 2017, 02:50:03 am
content: Quote from: HackedFridgeMagnet on June 11, 2017, 01:39:17 amBidding on a contract they can't deliver on safely is entirely dishonest, luckily the council is on the ball and able to critically appraise the bids which has lead to this post. Its not street lighting but some colour addition to a park where the council are probably rightly worried about the publics ability to get close to the luminaires.

author: cdev
author_rank: Super Contributor
timestamp: June 11, 2017, 02:57:48 am
content: Blue light tends to be problematic because it causes oxidative stress to the retina and lens of the eye more than other visible light colors.There is tons of research on it.Example:https://www.ncbi.nlm.nih.gov/pubmed/28251076https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5313540/"RESULTSERG results showed the blue LED group induced more functional damage than that of green or red LED groups. H&E staining, TUNEL, IHC, and TEM revealed apoptosis and necrosis of photoreceptors and RPE, which indicated blue LED also induced more photochemical injury. Free radical production and iron-related molecular marker expressions demonstrated that oxidative stress and iron-overload were associated with retinal injury. WB assays correspondingly showed that defense gene expression was up-regulated after the LED light exposure with a wavelength dependency.CONCLUSIONThe study results indicate that LED blue-light exposure poses a great risk of retinal injury in awake, task-oriented rod-dominant animals. The wavelength-dependent effect should be considered carefully when switching to LED lighting applications.Keywords:retinal light injury, LED light injury, blue light injury, iron, light injury mechanisms, oxidative stress"Source:Int J Ophthalmol. 2017; 10(2): 191–202. Published online 2017 Feb 18. doi:10.18240/ijo.2017.02.03PMCID: PMC5313540Light-emitting-diode induced retinal damage and its wavelength dependencyin vivoYu-Man Shang,1Gen-Shuh Wang,1David H. Sliney,2Chang-Hao Yang,3,4andLi-Ling Lee5----------Antioxidants help.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2017, 03:18:38 am
content: Ok mistake on street light. Sorry.Quote from: HackedFridgeMagnet on June 11, 2017, 01:39:17 amWell have you got an answer to this? All I can see that it is similar to any other visible light.p.s. Not talking about UV.AFAIK Cree LEDs have less UV than halogen bulbs which kids shine into each others eyes all the time.

author: Brumby
author_rank: Unknown
timestamp: June 11, 2017, 03:32:38 am
content: Quote from: CopperCone on June 11, 2017, 12:12:27 amI have encountered some public toilets that are illuminated with blue light. It is very uncomfortable and I'm happy to exit as soon as possible - and that is the intent. It deters those undesirables that might otherwise lurk there for various reasons.As for colour changing lighting for a park - I have a couple of questions....What is the purpose of this lighting? Is it for entertainment or artistic embellishment ... or is it for illumination of the area for safety?If for safety illumination, I have a problem with any lighting that is not completely static - or at least extremely slowly changing (as in - not noticeable over a 5 second period or longer). While human visual perception can identify an object in a static scene, it can more quickly identify changes in a scene. With static lighting, those changes are more commonly moving objects - like people - whereas a bright flash of a changing light can grab the observer's attention and they might miss seeing a mugger take position.In addition to this, straight blue light is not the best for illumination anyway - and the shorter the wavelength, the worse it is. I would hope we could eliminate UV as a problem.If the lighting is for entertainment, then the impact questions change somewhat.Another question is how and where the lighting will be presented, specifically - how close to people will it be and will the emitters be beaming directly at people's eyes - or will they be diffused or indirect? The most obvious question is: How bright will they be?There are lots of questions that could be asked and there are lots of opinions that could be offered - but it might help narrow down discussion to something more helpful if we were to be offered a typical example of what the council is being offered.

author: Someone
author_rank: Super Contributor
timestamp: June 11, 2017, 03:44:19 am
content: Quote from: HackedFridgeMagnet on June 11, 2017, 03:18:38 amIts not a straight lux limit, nothing so simplistic is possible and the design needs a lot of the installation parameters to determine if its safe or not. The blue and red extremes of visible (or invisible) light are not directly comparable to a broadband source like a halogen luminaire, as the natural blink response protects against inadvertent over exposure there. They need to hire an engineer (probably optical) with the requisite experience to provide the documentation the council is wanting.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2017, 04:06:46 am
content: Quote from: Someone on June 11, 2017, 12:00:11 amQuote from: Someone on June 11, 2017, 03:44:19 amOk so it is not simple. So why do you call him a cowboy? It seems unfair.Then for anybody putting in RGB LEDs are they that dangerous?Are they more dangerous than what they are replacing?You talk about fundamental safety requirements, but what are the standards that the OP needs to adhere to?Are they more dangerous than for example putting a blue filter over a halogen?My feeling is that at any reasonable lux they are not dangerous. But I have no proof.Specialist engineers are expensive, so maybe we can just help him with some calculations. But short of 20000 lux I can't see an example of where they are dangerous.Happy to be enlightened.

author: Bud
author_rank: Super Contributor
timestamp: June 11, 2017, 04:16:58 am
content: Car blue-ish LED headlights are eye irritating.

author: X
author_rank: Regular Contributor
timestamp: June 11, 2017, 04:26:20 am
content: Quote from: Brumby on June 11, 2017, 03:32:38 amIt also makes it harder to spot blood vessels in that light, so it discourages drug addicts from shooting up.Quote from: HackedFridgeMagnet on June 11, 2017, 04:06:46 amOnly do so if you are comfortable with the probability that you will get sued when someone suffers retinal damage. First they'll sue the council, who will then sue the contractor, who will then sue the EEVBlog forum. The subject of lighting and health issues is an interesting topic to discuss in general though, as it isn't covered very much. I have seen a lot of office buildings which have more lighting than is required to light up a large footy oval, and hospitals and clinics with fluorescent lights (yes, the ones with mercury inside).Quote from: Bud on June 11, 2017, 04:16:58 amI believe they are illegal in Australia, as per the Australian design rules. An argument can be made that these are blue lights, which are forbidden. But that doesn't stop people.

author: MK14
author_rank: Super Contributor
timestamp: June 11, 2017, 04:27:20 am
content: Examples of why UK councils ARE bothered about (blue, colour temperature and LED lighting in general) led lighting.http://luxreview.com/article/2015/01/i-m-not-anti-led-buthttp://www.bbc.co.uk/news/magazine-38526254

author: Halcyon
author_rank: Unknown
timestamp: June 11, 2017, 04:34:22 am
content: I've seen this "blue light causes damage" thing popping up more and more often and it's bullshit. So much so there are "natural medicine" companies exploiting people who don't know any better with sciencey sounding claims and "technical" diagrams, such asthis company. Of course they don't make any direct claims as to their effectiveness, they are labeled here as"Aust L" products(as opposed to "Aust R" like real medications are that are actually tested as to their effectiveness) and they only make vague inferences between fact and what their pills actually do (next to nothing).Of course any light at bright enough intensity can cause damage to eyes, no doubt about that, but lets talk about the colour only.There is strong evidence that indicate that light (regardless of colour) can effect a person's circadian rhythms (i.e.: the "body clock) by suppressing the body's secretion of melatonin (a natural hormone in the body which regulates sleep/wake cycles).Studies have shown that blue light increases this suppression effect (which is why doctors recommend at least 1 hour of "screen-free" time before bed).Somehow people have twisted this as meaning blue light = bad and I'm sure you can find a "study" or two which would make these claims. Blue light is everywhere in abundance (including sunlight) and hasn't been a problem so far.Put this whole debate in the same category as the Batteriser in my opinion.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2017, 04:44:00 am
content: Quote from: X on June 11, 2017, 04:26:20 amNot worried about being sued,but I would like to know how the OP can calculate if his lights are safe, ie. Quote a standard or a study, hopefully one I can access and understand.ps. The mouse one didn't seem very reasonable. 100W of blue light for 12 hours at 20cm IIRC. poor mouse.So yes I can understand it is dangerous at some level but I doubt the OP is going to be producing this level of output.

author: MK14
author_rank: Super Contributor
timestamp: June 11, 2017, 04:51:21 am
content: As regards SAFETY advice, it is best to get it from reputable sources. Rather than random people on the internet.As far as I can tell (from at least one trustworthy source), LED (especially blue) lighting CAN be harmful. But it depends on your exact setup, light output, LEDs exact colour spectrum etc etc. So it is probably difficult to give a precise answer here without knowing EXACTLY what you are planning and without being an expert in that precise field.

author: jh15
author_rank: Frequent Contributor
timestamp: June 11, 2017, 05:11:52 am
content: Blue is the color of the sky. The blue laden lights pollute in this band the most. You get a major sky dome glow over lamps of bluish color.I gave a talk at the request of a light pollution education advocate and lighting engineer. Way before LED could have replaced mercury halogen and sodium lamps.My demo was sky pollution, something like 6 billion dollars a year of light wasted to the sky. Look at the space shuttle pictures.Light trespass to neighboring property, your bedroom window like daylight all night inhibiting melatonin.At the time I showed how the typical 150 watt mercury vapor barn burner "security" lights were nicknamed burglars friends.A year later, still new to Maine, wife and I were checking out a new restaurant.Some old guy came over to our table.Are you the guy that spoke at the (3 towns association) light pollution meeting at the fire department building?It was standing room only and I had never done a public talk.. But I did have watt meters, demos and DATA.He said one town took out 50% of the streetlights, and upgraded the rest. million dollar savings? never checked it out.Lighting for time needed, not dusk to dawn, the right amount, the right place, and now the right color.I used to promote mainly don't pay for light in your neighbors bedroom or the sky. Lighting only your own property. Otherwise neighbors, and yourself pull down shade, the bad guys know this.But with all the new LED signs, "security" lights. I GIVE UP.At the "used to be dark" salt marsh, an Audubon preservation a mile from me there is now a crosswalk lit dusk to dawn with huge bluish street lamps.Central Maine Power grid tied little solar panels making a bluish 20 degree dome in the sky where it was once dark. ALL winter where the crosswalk is not even usable.Check out the international Dark Sky Association. dark sky dot org. I'm too old to get upset, so I just binge on eevblog.

author: Someone
author_rank: Super Contributor
timestamp: June 11, 2017, 06:37:34 am
content: Quote from: HackedFridgeMagnet on June 11, 2017, 04:06:46 amI'll happily call them cowboys, trying to cash in on a council tender when they don't have the competencies to do it safely. If you add some LEDs around your doorway and a child comes door knocking at night, stares into one of the LEDs, and loses their vision, it would be on you as the owner/installer. LEDs have been able to produce eye hazards for a long time (thinking 20 years here) so its not something new and challenging but a well known problem which has to be designed into any lighting system.You have neither proof, nor the willingness to learn anything here even with the glaringly obvious links presented.Quote from: HackedFridgeMagnet on June 11, 2017, 04:44:00 amWelcome to the real world.. some things are hard, expensive, and in this case required for the safety of the public.

author: X
author_rank: Regular Contributor
timestamp: June 11, 2017, 08:08:43 am
content: Quote from: Someone on June 11, 2017, 06:37:34 amThere are different types of cowboys. There are evil cowboys who know how to cash in on things, stupid cowboys who don't know what they are doing and are hired because they are cheap, and good cowboys who can get frustrated with the tight budgets and tight scheduling set by the clientele, and end up doing the bare minimum because of these factors. Cowboys nevertheless.Quote from: Someone on June 11, 2017, 06:37:34 amOther things are not necessary at all, and are just a way for governments to look "cool" and "hip" and "in with the flow" and whatever. I am increasingly dismayed that the Australian government (as well as some state governments) are pushing unnecessary tech/upgrades and trying to make their software, logos, websites, and adverts look like they were intended for coffee-hogging smartphone-addicted yuppies.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2017, 10:00:34 am
content: Quote from: Someone on June 11, 2017, 06:37:34 amYet again falsely accusing people. Grow up.If your so smart then take me from those glaringly obvious links to the proof that Blue LEDs are bad for peoples eyes.You wont because you can't, all you are doing is blustering.Look at the cree link, they say all their LEDs are intrinsically safe except for one, the Royal Blue XR-E which was meant for aquariums.The wikipedia doesn't say much but then links to other sites that aren't conclusive either.eg.https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3948029/andhttps://web.archive.org/web/20160304032134/http://www.ozgled.com/en/displaynews.html?newsID=69834

author: TheUnnamedNewbie
author_rank: Super Contributor
timestamp: June 11, 2017, 10:34:41 am
content: I ain't no expert, but I know a guy who is. I was skeptical too (still am!) as to just how bad this was. However, he has pointed me to a few university articles on the topic, and they have made me give it a "mhh, might be something to this".What all of them point to is not real "blue" that is the issue - it's near UV that causes problems. According to him, this is present in much white LEDs because it's nice to push into a phospor mixture to give you white light. The near UV (350-400nm IIRC) taxes your eyes because they aren't very sensitive to it - you don't "See" it as bright because the other colors in the LEDs are softer, so your iris opens up wider. It then tires out your rods and cones, causing symptoms such as prickling/stinging sensation inside or on top of the eyes, fucks up melatonin cycles, headaches, ...I have glasses with a UV filter built in and I have to say it seems to have helped with the symptoms. I notice when I forget putting them on that I feel the stining sensation after a few hours, but not when I have them on. (This suggests to me that it might be more than a placebo - when I forget I'm not wearing them it comes back. even though if it was just placebo it should still be gone).The annoying thing is that whenever you try to find studies, you are overwhelmed with the "feelgood technology evil must protect everyone think of the children" type pages, that make bold claims ("90% of all eye-strain cause by blue light") with no research links - it makes it hard to take the thing serious. There do seem to be some papers suggesting there might be something to it but I don't have the time to filter through them right now.

author: VK3DRB
author_rank: Super Contributor
timestamp: June 11, 2017, 10:34:57 am
content: Quote from: f5r5e5d on June 10, 2017, 11:49:35 pmBad google fu?Maybe you should get all that foo out from under your shift key.

author: m98
author_rank: Frequent Contributor
timestamp: June 11, 2017, 11:03:38 am
content: This whole discussion is so pointless. Just get the lights certified by the applying standards by an accredited testing and certification institute. Which standards, which institute? There are consulting firms happily taking a lot of your money for exactly that advice.

author: Someone
author_rank: Super Contributor
timestamp: June 11, 2017, 11:04:27 am
content: Quote from: HackedFridgeMagnet on June 11, 2017, 10:00:34 amIgnore the colour for a moment.Quote from: Halcyon on June 11, 2017, 04:34:22 amAny lighting could cause eye damage, LEDs are particularly bad as they can can have extremely high radiant intensity at the surface of the luminaire. You can find red, yellow, or green LEDs that will cause immediate and irreversible eye damage if looked at directly. But blue light is even more dangerous from a energy hazard as it has more energy per perceived brightness by one to two orders of magnitude. A pure blue light can be much more dangerous than a green or board white spectrum, just as 808nm (borderline IR) light sources are dangerous. This is well established and cree go on to say:Quote from: creeYour lack of understanding of the problem is on par with the OP, in no way should you be providing any advice or suggestions about lighting safety, such a strong statement is supported by your dangerous summing up of the cree data:Quote from: HackedFridgeMagnet on June 11, 2017, 10:00:34 amYou're not even in the ball park when it comes to this field, either start learning or back down.THIS:Quote from: MK14 on June 11, 2017, 04:51:21 amHire a professional with proper insurance and licensing (where appropriate), don't compromise on the safety of the public. I'm impressed the council are astute enough to push back on this.

author: R005T3r
author_rank: Frequent Contributor
timestamp: June 11, 2017, 12:42:49 pm
content: I think that this parameter have to play a very important role on your demonstration:https://en.wikipedia.org/wiki/LuminanceHowever, the whole thing just don't fit together. We should at least define "safe"...

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: June 11, 2017, 01:05:32 pm
content: Sorry I badly misquoted the CREE datasheet.from the table in the datasheet.Not sure where I got the "LEDs are intrinsically safe except for one" from. Was reading some other stuff at the time.What they did say was all their LEDs in the rG-2 category.QuoteQuoteSo what? they added a qualifer, it's applicable to all colours.Quote from: Someone on June 11, 2017, 11:04:27 amI'll ask again.If your so smart then take me from those glaringly obvious links to the proof that Blue LEDs are bad for peoples eyes.You wont because you can't, all you are doing is blustering.

author: CopperCone
author_rank: Super Contributor
timestamp: June 11, 2017, 03:49:47 pm
content: Quote from: Brumby on June 11, 2017, 03:32:38 amthe toilet trolls you.But having them outside is a different story. Some people like spending time outside near their apartment for stress reasons etc.. having disgusting lighting ruins this

author: xrunner
author_rank: Super Contributor
timestamp: June 11, 2017, 03:58:42 pm
content: Isn't this like asking if water is bad for you? Well, not if you are dying of thirst, but if you are drowning ... yea it's bad for you. It all depends on the situation.

author: f5r5e5d
author_rank: Frequent Contributor
timestamp: June 11, 2017, 04:02:58 pm
content: treez - you should hope you, your company can't be linked to this threadif there are actual adults at your company that see this thread they should rein you in sharply before this thread is linked to the company - if not can you outrightand you have burnt a username for any future jobs asking for examples of your online engineering activityso far you have shown emotional immaturity with tit-for-tat trollish 'counterpuch' attacks on people trying to help when you saw something not in line with your narrow idée fixeand intellectual immaturity by not welcoming the broadening of the discussion, trying to learn real issues to make you company's presentation, offer more acceptable

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 11, 2017, 04:14:04 pm
content: Quote from: Someone on June 11, 2017, 11:04:27 amIt is perfectly appropriate to use the internet to search for such professionals. And presumably said professionals used the internet, libraries, company literature and other "informal" sources in gaining their expertise, since most will have professional education that predates the availability of luminaires with these intensity and color distributions.Whether you get professional help or continue on your own, make sure that you and your customer agree on the ground rules. Must the lights be safe for persons using binoculars, telescopes or other vision enhancing devices. What about someone on the roof of a tall vehicle driving under the lamp? Two kids taking a dare to see how long they can stare directly into the light? Workers doing lamp replacement? Is temporary dazzling acceptable? If so define temporary. Long list of things to consider and the discussion is as important as the answers and the physics.I will also comment that expertise in human factors (beyond just damage physiology) is appropriate in this question. As pointed out in the comments above the physical danger might result more from the lynch mob upset with the lighting than from direct damage to the eyes. Again, agreement with your customer about ground rules is imperative.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 11, 2017, 04:57:56 pm
content: Ask the council exactly what standards they require compliance to. IME, chances are they won't have a clue.

author: PlainName
author_rank: Super Contributor
timestamp: June 11, 2017, 05:02:10 pm
content: Quote from: f5r5e5d on June 11, 2017, 04:02:58 pmYou know, it's quite easy to make a strong point without resorting to juvenile ad hom attacks such as this. Even more so not to use then from the very first post.Whatever point you may actually have, it is lost in the attention-seeking, ego-tripping bluster you present it with. Perhaps if you were polite and calm the relevant people might a) listen to you and b) engage with whatever issue you are presenting.

author: cdev
author_rank: Super Contributor
timestamp: June 11, 2017, 06:48:35 pm
content: Blue LEDs don't last as long as other colors. So buying blue LEDs with public funds seems foolish.

author: cdev
author_rank: Super Contributor
timestamp: June 11, 2017, 07:08:08 pm
content: There actually is an issue with retinal damage, caused by free radicals. Depending on your body's cells redox status exposure to bright blue light may cause retinal damage and it may not.https://www.ncbi.nlm.nih.gov/pubmed/26743754Pro-oxidant exposures also are additive and they use up your body's repair capacity faster. No toxicant stands alone, they are additive. Even common ones like diesel exhaust exposure, many solvents, ozone, and UV and very bright blue lights add up in terms of their impacts.People should also be aware that numerous antioxidants help protect against damage caused by these things. In my reading about blue light I saw that alpha lipoic acid which is a thiol and very cheap, is a good one for protection from blue light.Quote from: Halcyon onYesterdayat 22:34:22this company. Of course they don't make any direct claims as to their effectiveness, they are labeled here as"Aust L" products(as opposed to "Aust R" like real medications are that are actually tested as to their effectiveness) and they only make vague inferences between fact and what their pills actually do (next to nothing).Of course any light at bright enough intensity can cause damage to eyes, no doubt about that, but lets talk about the colour only.There is strong evidence that indicate that light (regardless of colour) can effect a person's circadian rhythms (i.e.: the "body clock) by suppressing the body's secretion of melatonin (a natural hormone in the body which regulates sleep/wake cycles).Studies have shown that blue light increases this suppression effect (which is why doctors recommend at least 1 hour of "screen-free" time before bed).Somehow people have twisted this as meaning blue light = bad and I'm sure you can find a "study" or two which would make these claims. Blue light is everywhere in abundance (including sunlight) and hasn't been a problem so far.Put this whole debate in the same category as the Batteriser in my opinion.

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: June 11, 2017, 07:22:19 pm
content: Quote from: cdev on June 11, 2017, 06:48:35 pmSource?

author: BravoV
author_rank: Super Contributor
timestamp: June 11, 2017, 07:34:26 pm
content: Quote from: mikeselectricstuff on June 11, 2017, 07:22:19 pm+1 , curious as well, as white led is actually a blue led underneath isn't it ?

author: Someone
author_rank: Super Contributor
timestamp: June 11, 2017, 11:42:41 pm
content: Quote from: HackedFridgeMagnet on June 11, 2017, 01:05:32 pmYou can keep ignoring the obviousQuote from: Someone on June 11, 2017, 11:04:27 amDesign of safe lighting for a public space is non trivial, it can't be distilled down to a one line equation or a couple of simple points. LEDs have been able to create hazardous light intensities for a long time, there is no question that LEDs (blue or otherwise) can cause damage to peoples eyes. The complex part is a) determining exposure limits and b) measuring or designing a luminaire to meet the limits.

author: cdev
author_rank: Super Contributor
timestamp: June 12, 2017, 12:55:47 am
content: "white" LEDs are made of broadband yellows and blue together, I think.I say that about blue LEDs because when I have several LEDs of different colors in a device the blue ones always get dimmer within a few years and the others don't seem to as much. I have some green LEDs in one setting that have been on continuously for what must be 15 years or more and they are still going strong.

author: Halcyon
author_rank: Unknown
timestamp: June 12, 2017, 01:04:45 am
content: Quote from: cdev on June 11, 2017, 07:08:08 pmThe abstract you linked to tells us nothing, it just mentions a blue LED. Can you link us to the full paper so we can actually examine the method and results in better detail? It also talks about mice. The discussion here relates to human exposure to blue light.Let's not start blurring the lines here, this is how facts become skewed. Humans have been exposed to an abundance of blue light from the sun with no ill effects.

author: helius
author_rank: Super Contributor
timestamp: June 12, 2017, 01:38:13 am
content: Quote from: Halcyon on June 12, 2017, 01:04:45 amSuch a generality is unfair to those who suffered retinal burns from directly viewing a partial eclipse of the sun. There are many situations where the natural response to bright lights is insufficient to protect the eyes, either because it is too slow or not equally sensitive to all spectra. Would you say that a visible Class III or IV laser is safe because the sun provides "an abundance" of light?

author: Halcyon
author_rank: Unknown
timestamp: June 12, 2017, 01:44:01 am
content: Quote from: helius on June 12, 2017, 01:38:13 amAs I mentioned in a previous post (and as others have already pointed out the obvious), ANY light, regardless of wavelength can be hazardous if it's bright/powerful enough, whether it be damage to the eyes, thermal burns to other parts of the body, seizures due to photosensitive epilepsy... etc...The discussion was specifically about light in the "blue" spectrum at "normal" intensities you would encounter in "normal" situations (such as walking through a lit park at night as the OP mentioned).As much as I feel for those with less-than-adequate vision, I wasn't talking about "abnormal" situations (such as looking at the sun during an eclipse, with no protection).Let's try to stay on-topic within the parameters of the OP. Everything and anything can be hazardous in small or great enough quantities; light, oxygen, coffee, staying up for days at a time arguing with people on the internet...

author: Someone
author_rank: Super Contributor
timestamp: June 12, 2017, 01:45:32 am
content: Quote from: Halcyon on June 12, 2017, 01:04:45 amHave fun working on the ethics review for performing an experiment on humans where you intentionally damage their sight. Animal models are used for very good reasons.

author: helius
author_rank: Super Contributor
timestamp: June 12, 2017, 02:05:23 am
content: Quote from: Halcyon on June 12, 2017, 01:44:01 amA. i. Two lamps of similar luminous intensity may have different spectra and therefore different radiometric potential for damage. The eye is less sensitive to blue, so a similar intensity of blue light has both higher radiant intensity, and higher photonic energy, than a yellow LPS lamp. There is no particular reason to believe that simply being "normal intensity" makes it safe.A. ii. A related issue is the means of diffusion and the geometry of the emitting surface. Different systems may project a similar irradiance into the environment, yet have different structures that are brighter from various angles. What if the outer envelope is broken, what does that do to the peak irradiance? In a gas discharge lamp, the radiation pattern is omnidirectional and a reflector is needed to project it downwards. In a LED, the pattern is unidirectional and some means of diffusion is needed. By breaking each type, the intensity of the LPS can only decrease, whereas the LED can become more intense in some specific direction.B. There are also human psychological factors at play. The sun is featureless to the naked eye, so (excluding rare astronomical conjunctions) people only stare at it when under heavy medication or otherwisenon compos mentis. Streetlights of traditional design are also nothing new and so there is no reason to stare at them. Any new installation that appears "interesting", particularly if it changes color or has some other novel feature, is going to be stared at.

author: cdev
author_rank: Super Contributor
timestamp: June 12, 2017, 02:15:53 am
content: Thank you for bringing this up. Human experimentation is against international laws.Quote from: Someone onTodayat 19:45:32

author: hamdi.tn
author_rank: Frequent Contributor
timestamp: June 12, 2017, 02:24:17 am
content: Hi,https://smartvisionlights.com/downloads/misc/iec62471-led-product-safety.pdfhttp://www.ledsmagazine.com/articles/2012/11/led-based-products-must-meet-photobiological-safety-standards-part-2-magazine.htmlApparently applicable standard for this case is EN IEC62471https://webstore.iec.ch/publication/7076Hope this help

author: jh15
author_rank: Frequent Contributor
timestamp: June 12, 2017, 03:01:07 am
content: skimming through here, yes low pressure sodium is efficient, doesn't bother annoying professional and amateur astronomers.Your car color may not look perfect. Just remember where you parked it.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 12, 2017, 04:02:10 am
content: Quote from: helius on June 12, 2017, 01:38:13 amhttp://www.repairfaq.org/sam/lasersaf.htm#safcilsEven a 1mW laser can be on the order of 100 times as intense as direct sunlight.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 12, 2017, 04:03:32 am
content: Quote from: cdev on June 12, 2017, 02:15:53 amIf this stuff is above your head you should definitely get competent assistance before selling design services in lighting, or selling public lighting installations. Either that or get good lawyers and large insurance policies.

author: cdev
author_rank: Super Contributor
timestamp: June 12, 2017, 04:12:19 am
content: CatalinaWOW, You're confusing me with the OP.

author: X
author_rank: Regular Contributor
timestamp: June 12, 2017, 04:48:58 am
content: Quote from: Someone on June 12, 2017, 01:45:32 amHowever, this still means these experimental results may not accurately reflect human responses. It is known that animal vision is different to human vision due to differences in the way the eyes are structured, so tests on other animals are not an ideal way of determining the effects on humans.

author: Someone
author_rank: Super Contributor
timestamp: June 12, 2017, 04:59:49 am
content: Quote from: X on June 12, 2017, 04:48:58 amA lot of OH&S limits get set by precedence from accidents, unintentional human experimentation. Then its known for sure what levels of hazard caused the damage and then animal models are used to find rates and thresholds. But feel free to question the entire basis of health research using animal models from your uninformed view point, the rest of us will get on with using the valuable information it provides.I'll skirt Godwins Law here and suggest some people are just never satisfied without having the exact data from real experiments on humans. The civilised world has decided thats not a sociable way to do things.We know that bright light sources can damage peoples vision, whats so hard to grasp here? If you dont like the scientific basis for setting the limits you can try and show how the studies are invalid rather than just dismissing them because you lack the understanding to see how they're relevant.

author: X
author_rank: Regular Contributor
timestamp: June 12, 2017, 05:23:47 am
content: Quote from: Someone on June 12, 2017, 04:59:49 amAt no point did I suggest that animal experimentation isn't useful, far from it. If this is not validated with experimentation on humans, it renders the resulting data open to questioning. You are introducing more independent variables here, which is the significant differences in traits in species. I see nothing wrong with suggesting that a human experiment will be more accurate, because it should be blatantly obvious that this is the case. Many medical studies are done on humans (commonly known asclinical trials) for this exact reason.Quote from: Someone on June 12, 2017, 04:59:49 amReal experiments on humans are regularly performed in the form of clinical trials, waiting for accidents to happen (often with devastating effects), and people volunteering for experimentation. Some experiments do not scale well if you perform them on rats, mice, and pigs. You don't need to be a doctor to work out that experimental results can (and often do) be challenged if the test isn't scientifically fair.Not all human experimentation is done in a Unit 731 type environment.Quote from: Someone on June 12, 2017, 04:59:49 amAgain, you are assuming that I am blankly disputing the claim. I am only agreeing that the data can be questioned, and in this case, it has. Bright light sources can damage vision, and has been proven time and time again. The point is whetherblue lightcan damage vision, not bright lights. I am not disagreeing with that either, just the validity ofonlyrelying on animals.On that note I first heard about this "blue light hazard" around 10 years ago, and I think human subjects were also studied, but I can't find any links to such a study now. It was also a specific wavelength of blue, near the low-end of the visible light spectrum, at elevated intensity, in concentrations not found in natural light (eg. blue sky).

author: Someone
author_rank: Super Contributor
timestamp: June 12, 2017, 06:08:51 am
content: Quote from: X on June 12, 2017, 05:23:47 amYou question it without any basis. Bring something forward rather than just question the validity of it when much more learned people than you or I accept that it is valid. The mammalian eye although having radically different physical structures across species follows the same chemistry, animal models are excellent ways to determine how blue light affects people differently to other light:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734149/Thats a recent review of the area.There are well established standards for exposure of humans to light of all wavelengthsQuote from: X on June 12, 2017, 05:23:47 amThis makes no sense, there will be thresholds, doses/quantities, and rates which can cause irreversible damage to people at any wavelength. It so happens that the eye is more sensitive than other parts of the body and limited by the optics and transmission of the retina. On top of that its known that the eye is more easily damaged by shorter wavelengths in the blue and into the UV.Quote from: X on June 12, 2017, 05:23:47 amOf course it can, and at less intensity than broadband white sources, green, or yellow light. Or do you mean to say: are there still effects of blue light below levels which physically damage the eye? Or are you looking for a linear no-threshold proof for blue light exposure? You could dedicate your entire life to answering that question and get nowhere. Even if there is a linear no-threshold mechanism (up to you to show one) a "safe" exposure can still be found which is based on acceptable damage rates over a persons lifetime.There is ongoing research about effects beyond the eyes function/damage into melatonin levels but thats not captured in the standards required for public safety (anywhere?). Perhaps that will be included in the future once more is known, perhaps it wont. The safe limits for blue light intensities might be revised up or down in the future based on new information as it becomes available.

author: Someone
author_rank: Super Contributor
timestamp: June 12, 2017, 06:13:36 am
content: Quote from: X on June 12, 2017, 05:23:47 amIts simply unethical (as considered by the vast majority of people) to do intentional harm to a living person even with their express consent. Not that the world will reject your results if you do choose to do the experiment on humans but very few people would ask for it, because thats unethical.You're welcome to destroy your vision to prove us all wrong, but I'm happy with animal models and will specifically say you shouldn't damage any persons sight.

author: X
author_rank: Regular Contributor
timestamp: June 12, 2017, 06:33:38 am
content: Quote from: Someone on June 12, 2017, 06:13:36 amOnce again, I am not referring to ethics or "sociability" or how "civil" it is to do experiments on humans, I am simply referring to the validity of applying the results to humans. This has nothing at all to do with ethics.I was agreeing with another poster that the results of an experiment performed on a mouse cannot be considered a definitive standard for a human, even though it can lead up to it. Animal testing is great for ironing out an initial hypothesis, and may well be fine for situations where human experimentation is not possible, but that's not the point either. The point is that a study conducted on humans will be far more credible in this case than a study conducted on mice.You can shift goal posts and throw as many accusations at me as you want, it does not invalidate Halcyon's initial point about questioning the application of results of animal experimentation on humans in this case. It also does not invalidate my point that experiments on animals cannot be a definitive standard for the effects on humans, without first seeing results in humans as well.

author: X
author_rank: Regular Contributor
timestamp: June 12, 2017, 06:58:21 am
content: Quote from: Someone on June 12, 2017, 06:08:51 amPutting it that way, I can appreciate that logic. Chemical reactions are unlikely to differ, but I would certainly be interested if there is a difference between people vs smaller animals in the intensity required for blue light to have a permanent effect.Quote from: Someone on June 12, 2017, 06:08:51 amAgreed, and there are examples of where this is useful (eg. JPEG compression relies on this by prioritising preservation of certain colours). Upon reading that, I think I made a bit of a mess there, my apologies.QuoteNot so much that, but rather what intensity is required for such damage to begin. I am not disputing that blue light can cause damage, but there is definitely a minimum intensity at which this can occur. It would be nice to have some experimental data which can provide a reasonable range here, rather than simply relying on mice. Although for reasons you have mentioned earlier, I doubt this is likely to happen.Quote from: Someone on June 12, 2017, 06:08:51 amFine by me, as we can only go by what is currently available. Whilst my point remains about the applicability of such data, I can appreciate that they can only go by what is available, and as I mentioned earlier animal models are the closest we can get at this stage.All that said, I am sure there is a study that was conducted on humans also (based on a sample of those exposed to this light as part of their occupation, IIRC) but I can't seem to find it. I remember reading about this years ago.

author: Halcyon
author_rank: Unknown
timestamp: June 12, 2017, 07:21:10 am
content: All things considered, no one here is yet to supply a source to any kind of respected international standard, WH&S regulation or medical journal which shows any strong evidence to suggest that blue light is detrimental to human eyesight under "normal" circumstances. The only "evidence" seems to be anecdotal at best and barely relates to humans at all.Optometry has been around since the early 1900's with light in the blue end of the spectrum being around far longer than humanity. Aside from the well-know influence on melatonin in the brain (which is not detrimental to eye sight), you may as well be arguing that green, or red, or pink sparkly light has a detrimental effect.But don't take my word for it, speak to an actual health care professional and research reputable sources. You'll find that the biggest issue will be with those that don't actually like the colour blue as a personal preference.

author: Someone
author_rank: Super Contributor
timestamp: June 12, 2017, 07:22:28 am
content: Quote from: X on June 12, 2017, 06:58:21 amSo without knowing what the accepted safe limits are or how they were arrived at you still want to question them? I'll stick to accepted standards as I'm obliged to by law and trust that they have been appropriately determined, because even if they're not perfect I'm not liable for those mistakes.

author: Someone
author_rank: Super Contributor
timestamp: June 12, 2017, 07:24:52 am
content: Quote from: Halcyon on June 12, 2017, 07:21:10 amStill doing your word play? Blue light has various intensity thresholds beyond where its considered unsafe, some damage may be done to some people even below that threshold. Why all the drama?

author: Halcyon
author_rank: Unknown
timestamp: June 12, 2017, 07:30:21 am
content: Quote from: Someone on June 12, 2017, 07:24:52 amWord play? I thought I was being fairly direct. Others might call it "English". But for your benefit, allow me to simplify: "People are bitching over nothing. Talk to a professional."Why all the drama? Again, allow me to be direct: Fuck knows?! People should be more worried about whether they should wear a jacket tomorrow or not.

author: X
author_rank: Regular Contributor
timestamp: June 12, 2017, 07:36:13 am
content: Quote from: Someone on June 12, 2017, 07:22:28 amCan't argue with that one. I have questioned a lot of standards which I am required by law to adhere to, and I'm more than willing to adhere to them, it gives me the legal ability to point fingers at the people who made the laws when someone gets hurt.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 12, 2017, 07:17:54 pm
content: Quote from: cdev on June 12, 2017, 04:12:19 amSorry for the confusion, but my comment was meant for the OP. Who should have been able to find these links on his own. I didn't read all of them, but in about 10 minutes of browsing I was able to identify a solid basis for damage thresholds and links to the "Standards" organization which would be the best authority on what is generally accepted as safe levels. These animal and petri dish studies are not definitive but do provide a lot of guidance.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: June 12, 2017, 07:37:07 pm
content: Unless the damage mechanism is thermal it seems unlikely that there will be any level at which no damage will occur. Even if the mechanism involves multi-photon reactions the damage is determined by photon energies. The best you can hope for is a level at which damage rate is less than whatever the eye's recovery/repair rate is. Assuming that it is non-zero.

author: Cerebus
author_rank: Super Contributor
timestamp: June 12, 2017, 08:05:10 pm
content: Quote from: f5r5e5d on June 11, 2017, 04:02:58 pmIt's so sweeet. He hasn't learned grammar, punctuation, how to use the shift key or put a whole sentence together - but he somehow thinks he's in a position to hand out advice on how to conduct oneself publicly in writing.

author: cdev
author_rank: Super Contributor
timestamp: June 13, 2017, 04:36:54 am
content: Blue light has value for a lot of things, for example in controlling microbial growth. Also, it can help people reset their circadian rhythms.(if used in the daytime) Also, in certain contexts its very relaxing. (But its all important to have the LEDs if you use LEDs not shining right into people's eyes.. To be relaxing they have to be reflected off of walls)(Strangely, interspersed with the material about the deleterious effects of bright blue light in some contexts are a bunch of fairly interesting articles on positive effects on life forms of pure colors of different wavelengths of light.)Dichroic lighting filters and fixtures are very interesting in that context. Dichroic lights have a very pure color, not unlike LEDs but the color can be varied by changing the angle the light impinges on the filter. And of course its subtractive, i.e. a filter for existing light. So it can be used structurally in architecture with really interesting and varied effects. One example is the award winning Harpa concert hall in Iceland.Quote from: CatalinaWOW onTodayat 13:17:54>Quote from: cdev onYesterdayat 22:12:19Sorry for the confusion, but my comment was meant for the OP. Who should have been able to find these links on his own. I didn't read all of them, but in about 10 minutes of browsing I was able to identify a solid basis for damage thresholds and links to the "Standards" organization which would be the best authority on what is generally accepted as safe levels. These animal and petri dish studies are not definitive but do provide a lot of guidance.