WHY CURRENT LED LIGHTING METRICS ARE INVALID
LED lighting technology is unlike any other form of conventional lighting we've used in the past as it has unique properties, characteristics and complexities. (The closest equivalent to LED lighting technology is laser.) Unfortunately, the complexity has been widely ignored, and in most cases misunderstood which is why there are so many failed LED retrofits around the world.
Rather than deliver safe, effective and appropriate illumination that significantly improves upon the older lighting it replaces, LED retrofits have instead caused all sorts of problems. Not only has the technology itself caused challenges, commonly used metrics for conventional lighting cannot be applied to LEDs. This is due to the fact that current metrics are based on spherical light emitters that emit uniform light, whereas LEDs are a flat surface emitter that produces high-intenisty light concentrated into a narrow beam that is non-uniform.
It's taken until 2021, for the lighting industry to finally admite they have made an error, with Cree Lighting being the first and only lighting company, as yet, to explain that the industry has been using the wrong metrics for LED lighting. Please check their white paper to learn more.
For more information about the different characteristics of LED lighting technology and why current LED lighting metrics are unsuited and invalid, please visit
https://www.softlights.org/why-is-led-light-different/
(The graph on the left above is the spectral power distribution (SPD) of a 4000 K LED streetlight (with the problematic spike in disruptive bluewavelengths of light circled in a red outline to highlight the issue). This kind of light source is complely inappropriate for lighting at night. SPD is a metric that provides information about the various wavelengths of light being emitted by a light source. This is especially important when deciding about the appropriateness of a light source for lighting at night, however, this metric is not being widely used.
THE DRAWBACKS OF LED LIGHTING TECHNOLOGY
Until all of the inherent drawbacks explained on this page are adequately understood and resolved, the LED lighting being installed in New Zealand, and elsewhere in the world, remains unfit-for-purpose. There are some options available which have an improved spectrum and delivery of light, although they still cannot emit the same quality of lighting that's produced by high-pressure sodium streetlights. Even with diffusing optics, improvements to the spectrum, quality drivers to reduce flicker, and adjustments to fixtures, LED lighting technology is biologically unsafe. The Lightwise Guild provides information about "safer" LED options as a compromise. While ALL artificial lighting at night has an impact on biology, we can minimise the effects by carefully selecting the least harmful light sources available.
While LED lighting technology has been hailed for its potential energy, operational and maintenance savings, other costs that far outweigh these savings have been overlooked and downplayed. (The argument for energy efficiency is also questionable because the light emitted by LED lighting technology is inferior in quality compared to older forms of lighting such as incandescent and halogen. If this is the first time you're reading this information, we encourage you keep an open mind and learn more here.
With the emphasis on energy efficiency, the disadvantages of this technology have not been given adequate scrutiny nor have the repercussions been duly considered. Complicating matters, those responsible for manufacturing, approving and installing LED lighting have continued to dismiss warnings of the risks from scientists, medical doctors, ophthalmologists, chronobiologists, neurobiologists, biologists, ecologists and educated lighting experts. There’s sadly, also a widespread lack of knowledge about the unique properties of LED technology.
As a result, New Zealand has numerous examples of costly failed LED retrofits which are negatively impacting residents, compromising their safety, harming their health and well-being, and reducing their life quality. The health of flora and fauna, and the biodiversity of ecosystems is also under threat. The same kind of problems have happened overseas and forced concerned members of the public to take legal action.
In December 2018, the Minister of Health, Hon. Dr. Dave Clark was presented with an appeal for safer LED street lighting. This appeal included the points below and they are still just as relevant today.
Lighting should first and foremost do no harm - and the large investment in LED retrofits should also mean that the new lighting is a significant improvement upon the lighting it replaces - however this isn't the case.
1 - EXCESS LUMINANCE
Most LED road lighting installed around the world produces excess luminance (too much light falls on the human eye). Their luminance is comparable to lasers and until 2006, LEDs were in the same IEC60825 classification. “LEDs emit light in a very unnatural fashion with incredibly high intensities when directly viewed, compared to any other light source, artificial or natural. Due to their high intensity along the centre optical axis of the luminaire, LEDs magnify light enormously at the 2 degree viewing angle at any wavelength in the entire spectral power distribution (SPD) of the LED, so even if peaks in the SPD are resolved, LEDs will still cause detrimental effects from blue light, as well as any other wavelength of light within the SPD.”[1] Excess luminance causes disability glare, visual discomfort and impairs vision which reduces safety when driving, crossing streets and navigating thoroughfares. It’s also detrimental to eye health.[2]
To learn more please listen to this podcast where Dr. Nisa Khan is interviewed and explains this issue.
2 - PARTICULARLY UNSUITED FOR THE NEW ZEALAND POPULATION
Stephen Mason, an Australian optometrist explains, “As many eye clinicians are aware, New Zealand has an unusually high level of keratoconus per head of population. Keratoconus is a degenerative eye disease of the cornea that causes astigmatism and associated problems of photosensitivity and significant susceptibility to glare. Patel 2012 [3] states, New Zealand appears to have the highest reported proportion of (corneal) transplantation surgery for keratoconus worldwide.” [4] The glary, high-intensity light emitted by LED road lighting will cause major problems for many New Zealand citizens.
3 - EXCESS GLARE
The vast majority of LED streetlights produce significant glare which is caused by two factors: excess luminance (explained above) and blue-rich white light. Blue wavelengths of light scatter readily in the eyeball causing disability glare. This impedes vision and can force a person to instinctively look away from the light source.[5] Glare reduces safety and is hazardous for drivers, cyclists, pedestrians and residents. Although glare can be partially mitigated by dimming, the problem itself needs to be resolved with specific technology.[6] (Cree is the first large lighting manufacturer to openly admit most residents don’t want to live next to harsh, bright and glary LED road lights – and in response, developed a glare-free, warm white 2700 K luminaire.)[7] Dimming requires a central management system (CMS) but some municipalities do not have the budget to take advantage of adaptive features.
4 - REDUCES VISUAL ACUITY AND SAFETY, POSING A HAZARD
The human visual system is incredibly complex and there’s still much we don’t understand. We do know that the blue-rich light and excess luminance produced by high-intensity LED road lighting worsens glare, increases visual disturbances, and can also reduce mesopic vision needed when driving at night. As a result, these LEDs decrease visual acuity and safety, and pose a road hazard.[8],[9]Drivers 40+ years, as well as those with the degenerative eye condition keratoconus (a common form of astigmatism) are especially at risk, and glare is particularly problematic for the elderly as it causes loss of contrast which obscures night vision.[10],[11] Furthermore, glare increases during poor driving conditions as blue wavelengths reflect off water molecules making white LEDs less effective in rain, mist, fog and snow. Signify Lighting (previously Philips) provides a comprehensive technical lecture on their website, by lighting expert Wout van Bommel. He explains why blue-rich white LEDs road lighting is unsuitable for road, traffic and pedestrian safety, especially for our aging population.[12] To watch please click here.
5 - DISRUPTIVE BLUE-RICH LIGHT
Artificial light at night (ALAN) is correlated to the development of cancer. (The World Health Organisation declared exposure to ALAN a Class 2a carcinogen.)[1]And short wave blue-rich white light emitted from white LEDs in particular, is associated with eye damage, and a wide range of diseases. Studies indicate it also renders drugs used to treat cancer ineffective, due to the inhibition of melatonin, a known anti-carcinogen.[13],[14],[15],[16],[17],[18],[19],[20],[21],[22],[23],[24]
Dr. Alexander Tups, from the University of Otago, who researches light-mediated melatonin suppression says, “Just one minute of exposure to blue-rich white light from 4000 K LED streetlighting is sufficient to suppress melatonin production for three hours”.[25] He believes more research is needed to determine the health risk of white LEDs. Professor Richard Stevens, a cancer epidemiologist at the University of Connecticut, who studies the links between artificial light and health explains, “There’s a global effort to roll out these very bright LED lights without adequate vetting of how it might affect human health and ecology”.[26] Associate Professor David McBride from the department of Social and Preventive Medicine at University of Otago, states, “The introduction of LED lighting may not therefore be health risk free: we need to know a lot more about the possible effects”. [27]
6 - PHOTOTOXICITY
LEDs with a CCT of (2700-4000 K) emit oxidising blue-rich light which is phototoxic to the human eye. This can damage the ocular surface and retina, as well as cause cell death.[28],[29],[30] Researchers advise the associated oxidatively damaged biomolecules, cell destruction, and chronic inflammation should be carefully considered when switching to LED lighting.[31]
Not only that, Dr. Abraham Haim from Haifa University, Israel explains, “The retina of the human eye produces melatonin, but blue wavelengths of light emitted from LEDs prevents that, so the eye is even more susceptible to the photodamage caused by these light sources.” [32]
Most importantly, recent research suggests retinal toxicity may occur at occupational domestic illuminance and not only in extreme experimental conditions. Repeated exposure has not been accounted for.[33]
7 - INAPPROPRIATE SPECTRAL POWER DISTRIBUTION (SPD)
LEDs 2700 K and greater, (and many 2200 K LEDs as well), emit a peak in disruptive, light-scattering, blue wavelengths of light which trick organisms into thinking it’s daytime and prevents the production of melatonin. At night, this can harm health, compromise wellbeing, disturb wildlife and increase light pollution. (The current mainstream metric Correlated Colour Temperature (CCT) is inadequate because all it does is provide a rough guide to how "cool" or "warm" a light source appears to the human eye. It does not provide information about the wavelengths of light it emits.)
8 - LACKS PROTECTIVE WAVELENGTHS OF LIGHT
Unlike natural sunlight, white LEDs lack sufficient protective red wavelengths to counteract the oxidising effects of blue wavelengths mentioned in Point 6. Also, wavelengths such as near-infrared radiation (750–950 nm) are absent in LEDs and studies reveal these light frequencies can repair damaged retinal cells .[34],[35].
Red and near infrared light also has other benefits to human health.
To learn more please watch this informative presentation by Dr Alexander Wuncsh - click here.
There is currently only one lighting company we know of at the moment (October 2023) that has acknowledged the ill effects of LED lighting and has integrated red and near infrared wavelengths of light into their products. To learn more click here.
9 - HIGH INTENSITY LIGHT
The intensity of light emitted by LEDs is not only temporarily blinding, it causes the pupil to contract which prevents dark adaption, so the ability to detect objects in the shadows and adjust to low light conditions is lost.[36] This reduces safety and security.
10 - HIGH DIRECTIONALITY AND NON-UNIFORM LIGHT DISTRIBUTION
LED light sources are highly directional making them unsuitable for lighting wide areas like roads. Unlike high-pressure sodium, low-pressure sodium and metal halide road lighting which disperse light evenly in all directions, LEDs are highly directional so light distribution is non-uniform. To learn more about this please access the pdf files titled "Curved Versus Flat" in the downloads below.
This is observed as a limited area of intense brightness contrasted by a drop off into shadow which can cause a disorientating “zebra effect” in road illumination. Furthermore, non-uniform light distribution can reduce visibility, compromise safety and lower security. Street lighting engineers often add more luminaires which results in over lighting, more glare, extra disruptive blue wavelengths of light in the environment, and increased light pollution.] Lighting, Crime and Safety. Dark Sky International’s website. Accessed 10 October, 2018. https://bit.ly/2RN9vBV
11 - EXPOSED MODULES
LED road lighting has modules in a flat array which are exposed to the human eye. To reduce glare these modules should be sufficiently recessed, hidden from direct view, shielded and/or have suitable optics that cover the modules and diffuse the intensity of the light they emit. Vision is reduced when looking directly at a light source, which is why it’s best to avoid looking at a light source for any length of time, and also why there’s concern about the harm caused to eyes from white blue-rich LEDs, as warned by Public Health England (PHE).[37]
12 - FLICKER
Visible and invisible flicker can negatively effect and harm members of the public. John O’Hagan, head of the PHE’s Centre for Radiation, Chemical and Environmental Hazards, and a visiting professor in laser and optical radiation safety at Loughborough University explains, “Some people seem to be very sensitive to this light modulation, resulting in headaches, migraine and less specific feelings of malaise. However, most people will experience phantom arrays.”45 In April, 2018, Lux Review, released an online article which highlighted the problem of flicker raised in the PHE’s annual medical report. “Local authorities have been replacing mercury and sodium street lights with LEDs. If this is done purely on the basis of energy efficiency and cost, it is possible to end up with installations that may not be fit for purpose.”[38]
13 - INCREASED LIGHT POLLUTION
White blue-rich LEDs are increasing light pollution. Observations from space show areas of the Earth that were already artificially lit grew even brighter. [39] LEDs 2700 K and greater, have a much higher Scotopic/Photopic ratio (S/P ratio) than the older high-pressure sodium (HPS) road lighting. (HPS road lighting has a S/P ratio between 0.4 - 0.6, whereas 2700-3000 K LEDs have an S/P ratio of 1.3.) This means even with shielding, LEDs will worsen existing light pollution, doubling what we have now, impacting areas up to 100km away, as the short wave blue light they emit, bounce off the ground back into the atmosphere.[40]
14 - WIDESPREAD ENVIRONMENTAL DAMAGE
Due to their peak in blue-rich wavelengths of light, LED light sources can cause widespread environmental damage that affects entire ecosystems. There are negative consequences that haven’t yet been evaluated, which include economic costs such as reduced crop yield. Plant biologist, Steve Long says, “We’re gambling with our future in what we’re doing to the environment”.[41]
15 - REDUCED LIFE QUALITY IN NEIGHBOURHOODS
High-intensity LEDs produce glare which reduces safety, and they also often contribute to overlighting which can aid criminal activity.[42] More light equates with more crime and crime is clearly associated with loss of enjoyment of life and ill-health.
CONCLUSION
• LEDs cannot replace high-pressure sodium, low-pressure sodium or metal halide light sources on existing street columns on a one per one unit basis. There are simply too many different variables involved that all need to be considered and calculated properly.
• The 2018 Royal Society of NZ report on blue light states, “street lighting is a complex issue, with safety, road use and driving behaviour, visibility and environmental impacts to consider when choosing lighting options and further research is required to demonstrate substantial road safety effects for selecting white LED street lighting over high pressure sodium. Factors other than colour temperature such as lighting levels, uniformity, glare, waste light, energy consumption, reliability, maintainability and costs need to be considered.”[43]
• Until the problems highlighted here are properly resolved, such LED light sources remain unsafe, inappropriate and unfit-for-purpose.
• Solutions do exist that can improve the situation. Energy efficient, shielded, glare-free LEDs have been developed with diffusing optics, in a lower colour temperature (2700 K) with effective colour rendering index (CRI) and an appropriate SPD that will reduce light pollution, lower the impact road lights have on ecosystems, living organisms and biodiversity.. These luminaires are available in New Zealand, therefore, we recommend they should be the only LEDs approved, subsidised and installed in New Zealand on the main arterial routes. Energy-efficient, glare-free, amber LEDs 1800-2200 K with less than 1 percent of blue wavelengths of light and diffusing optics are also available but the NZTA needs to acknowledge the benefits of such lighting fixtures and update their M30 to include them as well.
• Non uniform light distribution can be resolved via lightpipe/waveguide technology and diffusing microlenses[44] as well as the proper choice and placement of luminaires.
• Flicker can resolved with quality LED drivers (but cheaper luminaires often don’t have them.)
Fit-for-purpose illumination provides immeasurable advantages and benefits – and every New Zealander deserves to have safer, responsible, effective lighting in their community.
* It's also important to acknowledge that many people cannot tolerate any exposure to the numerous unique characteries of LED lighting technology, even if the spectrum and delivery of light has been manipulated via optics and technology. This means that they are unfit-for-purpose.
Also visit https://lightaware.org/help-advice/guidance-for-businesses-and-designers
REFERENCES
1. Dr. M. Nisa Khan. Email communication with author. 22 April, 2018.
2. M.A. Contin et al. Eye (Lond). 2016. 30(2): 255–263. doi: 10.1038/eye.2015.221.
3. D. Patel, C. McGhee. Clin Exp Optom. 2013 Mar;96(2):183-7. doi: [10.1111/cxo.12006]
4. Stephen Mason. Email correspondence to author. October, 2018.
5. D.A. Schreuder. Road Lighting for Safety. (London: Thomas Telford Publishing. 1998). p. 107.
6. Dr. M. Nisa Khan. Understanding LED Illumination. (CRC Press. 2014.) Chapter 6.
7.. Cree Lighting Inc, youtube channel. Accessed 1 October, 2018. https://www.youtube.com/watch?v=7Wgi9uPvNHY
8.. Phys Org Science Website. Accessed 28 Aug, 2018. https://phys.org/news/2016-06-ama-affirms-human-health-impacts.html
9. American Medical Association Website.Accessed 10 Aug, 2018. www.ama-assn.org/ama-adopts-guidance-reduce-harm-high-intensity-street-lights
10. M. Motta. “U.S. Physicians Join Light-Pollution Fight”. News. Sky & Telescope. 22 June 2009.
11. N. Gruber et al. Traffic Inj Prev. 2013;14(5):477-85. doi: 10.1080/15389588.2012.727510.
13. K. Straif et al. Lancet Oncol. 2007 Dec;8(12):1065-6. doi: 10.1016/S1470-2045(07)70373-X.
14. Tulane University Website. Accessed 10 Aug 2018. - http://www.ohr.tulane.edu/news/releases/pr_072514.cfm?RenderForPrint=1
15. R.A. Al-Naggar, S. Anil. Asian Pac J Cancer Prev. 2016; 17(10): 4661–4664. doi: 10.22034/APJCP.2016.17.10.4661.
16. A. Garcia-Saenz et al. Environ Health Perspect. 2018 Apr 23;126(4):047011. doi: 10.1289/EHP1837.
17. K.E. West et al. J Appl Physiol. (1985) 2011 Mar;110(3):619-26. doi: 10.1152/japplphysiol.01413.2009.
18. Y. Cho et al. Chronobiol Int. 2015 32(9):1294-310. doi: 10.3109/07420528.2015.1073158.
19. S. Hurley. Epidemiology. 2014 Sep;25(5):697-706. doi: 10.1097/EDE.0000000000000137.
20. R.G. Stevens et al. CA Cancer J Clin. 2014 May;64(3): 207-218. doi: 10.3322/caac.21218.
21. E. McFadden. Am J Epidemiol. 2014 Aug:1;180(3):245-50. doi: 10.1093/aje/kwu117.
22. Y. Touitou et al. Life Sciences. 2017 March;173, 94-106. doi: 10.1016/j.lfs.2017.02.008
23. K. Obayashi et al. J Affect Disord. 2013 Oct;151(1):331-6. doi: 10.1016/j.jad.2013.06.018.
24. A. Keshet-Sitton et al. Integr Cancer Thera. 2016 16(2): 176–187. doi: 10.1177/1534735416660194.
25. S.E.Bauer et al. Int J Health Geogr. 2013 Apr 17;12:23. doi: 10.1186/1476-072X-12-23.
26. Dr. Alexander Tups interviewed by author. 6 September, 2016, Physiology Department, Otago University, Dunedin.
27. Daily Mail UK Website. Accessed 10 Aug, 2018. https://dailym.ai/1cD4yUt
28. V. Marek, et al. Free Radic Biol Med. 2018 Oct;126:27-40. doi: 10.1016/j.freeradbiomed.2018.07.012.
29. I. Jaadane et al. Free Radic Biol Med. 2015 Jul;84:373-384. doi: 10.1016/j.freeradbiomed.2015.03.034.
30. Y. Kuse et al. Sci Rep. 2014 Jun 9;4:5223. doi: 10.1038/srep05223.
31. Yu-Man Shang et al. Int J Ophthalmol. 2017; 10(2): 191–202. doi 10.18240/ijo.2017.02.03.
32. Personal Interview with Dr. Abraham Haim, 24th December, 2018.
33. A. Krigel. Neuroscience. 2016 Dec 17;339:296-307. doi: 10.1016/j.neuroscience.2016.10.015.
34. K.M. Zielinska-Dabkowska. Make lighting healthier. Nature. 2018 Jan 18;553(7688):274-276. doi: 10.1038/d41586-018-00568-7.
35. J.T. Eells, et al. Mitochondrion. 2004 4, 559–567.
36. Lighting, Crime and Safety. IDA’s website. Accessed 10 October, 2018. https://bit.ly/2RN9vBV
38. Lux Review Website. Accessed 28 August, 2018. http://luxreview.com/article/2018/04/street-light-flicker-is-new-hazard-says-watchdog
39. C.M. Kyba et al. Artificially lit surface of Earth at night increasing in radiance and extent. Sci Adv. 3:e1701528, 2017.
40. Otago Daily Times Website. Accessed 9 September, 2018. https://www.odt.co.nz/opinion/science-can-inform-better-lighting-decisions
41. A. Irwin. The Dark Side of Light. Nature. 553, 268-270 (2018) doi: 10.1038/d41586-018-00665-7.
42. Astronomical Society of Victoria Website. Accessed August 12th, 2018.
https://asv.org.au/downloads/ARationalefortheMandatoryLimitationofOutdoorLighting.pdf
43. Royal Society of New Zealand Report on Blue Light – Evidence Summary. November 2018. Pg 8.
44. Dr. M. Nisa Khan. Understanding LED Illumination. (CRC Press. 2014.) Chapter 6.
Keep in mind that all of the major players in LED lighting have sold their lighting divisions. This includes Osram, Philips, Cree and GE.