61–70 of 108 posts
As a former, quasi-astronomer, nothing at night is more impressive than a star lit sky. My first night in Colorado was unbelievable.
Let's break down their claims. > unseen blue light I have unread negative comments about this sloppy writing. They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature. > The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light. 4000K is actually considered fairly mellow. Above 6…
This is an obnoxiously dismissive comment build on ignorance and shoddy reasoning and an “I don’t care what you think just suck it up and stop complaining” approach to design/policy. The moon is one (1) singular source of light with a known peak intensity, often blocked by trees or clouds, and only at its brightest one day every month. On a full moon night, the moon is high overhead, not directly in your field of vie…
You are confusing color temperature with how the lights are installed. If your streetlights were 4000K and spaced properly you wouldn't have an issue with them. The penny-pinching distribution (high lumens, wide angle, distantly spaced) of lights chosen by your city is at fault. That layout will create maximum glare and is the most miserable layout imaginable since distant lights will always be shining directly in your eyes.
Let's break down their claims. > unseen blue light I have unread negative comments about this sloppy writing. They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature. > The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light. 4000K is actually considered fairly mellow. Above 6…
This is an obnoxiously dismissive comment build on ignorance and shoddy reasoning and an “I don’t care what you think just suck it up and stop complaining” approach to design/policy. The moon is one (1) singular source of light with a known peak intensity, often blocked by trees or clouds, and only at its brightest one day every month. On a full moon night, the moon is high overhead, not directly in your field of vie…
But you make some good points. I support your recommendations.
Earlier quoted context omitted.
Citation? That's a bold claim. As phrased, it also sounds really far-fetched since cataracts are not a disease of the retina. Maybe that's a problem with the phrasing and not the claim, though.
A quick goog of blue+light+retina+study brings up quite a few legit sites. The one I am going to read for my edification on the subject: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3144654/
I didn't read this entire article, but it seems to be discussing the general mechanism of light damage. There was no reference to LEDs. I'd want to see something that gave reason to believe that the blue in LEDs poses a threat.
Let's break down their claims. > unseen blue light I have unread negative comments about this sloppy writing. They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature. > The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light. 4000K is actually considered fairly mellow. Above 6…
http://press.endocrine.org/doi/abs/10.1210/endo-119-5-2201?j...
http://jap.physiology.org/content/110/3/619.short
Fires and the moon emit very little light at this frequency.
Earlier quoted context omitted.
Citation? That's a bold claim. As phrased, it also sounds really far-fetched since cataracts are not a disease of the retina. Maybe that's a problem with the phrasing and not the claim, though.
I'm not an eye doctor. It was explained to me that LEDs output blue wavelengths not present in the natural environment. Our eyes filter out many wavelengths but never saw these during evolution so the light goes right through their filters. The energy then dissipates in your eye and causes damage.
So I'm no expert but I don't think this is true. All wavelengths of light exist naturally in some amount.
> The energy then dissipates in your eye and causes damage.
Energy "dissipating" in the eye is how you see.
http://darksky.org/wp-content/uploads/bsk-pdf-manager/AMA_Re...
A representative section.
"It is estimated that a “white” LED lamp is at least 5 times more powerful in influencing circadian physiology than a high pressure sodium light based on melatonin suppression. Recent large surveys found that brighter residential nighttime lighting is associated with reduced sleep time, dissatisfaction with sleep quality, nighttime awakenings, excessive sleepiness, impaired daytime functioning, and obesity. Thus, white LED street lighting patterns also could contribute to the risk of chronic disease in the populations of cities in which they have been installed. Measurements at street level from white LED street lamps are needed to more accurately assess the potential circadian impact of evening/nighttime exposure to these lights."
Earlier quoted context omitted.
This is an obnoxiously dismissive comment build on ignorance and shoddy reasoning and an “I don’t care what you think just suck it up and stop complaining” approach to design/policy. The moon is one (1) singular source of light with a known peak intensity, often blocked by trees or clouds, and only at its brightest one day every month. On a full moon night, the moon is high overhead, not directly in your field of vie…
Yes, I was a little glib. But nonetheless life on Earth (not just our species) evolved with a 4100K light source at night. You are confusing color temperature with how the lights are installed. If your streetlights were 4000K and spaced properly you wouldn't have an issue with them. The penny-pinching distribution (high lumens, wide angle, distantly spaced) of lights chosen by your city is at fault. That layout will…
I have spent 10 years studying color science. I know what color temperature is. I’m just explaining why the moon is a poor analogy. I have an issue with bright short-wavelength light sources at night, regardless of lamp configuration. It knocks out night vision.
There is a wide literature (dozens if not hundreds of research papers) on this topic. It’s not exactly some deep mystery.
The lamp configuration just makes things worse (and the use of fewer, brighter lamps provides much of the economic incentive to install the new lamps, along with federal subsidies).
Let's break down their claims. > unseen blue light I have unread negative comments about this sloppy writing. They also repeatedly use the word "intense" incorrectly. Intensity refers to candela. Not lumens or temperature. > The original LED streetlights had temperatures of at least 4000K, which produces a bright white light with a high content of unseen blue light. 4000K is actually considered fairly mellow. Above 6…
What matters isn't color temperature, but the presence or absence of light in the range 360-405 nanometers, which activates certain neurons in the retina that suppress melatonin secretion. This light can be "unseen" because visual receptors don't respond particularly strongly to it, so it can be masked by much stronger emissions of yellow light. However, it still has an effect. Color perception is irrelevant in this…
*Future generation of LEDs might shift from indigo (445nm) to violet to improve color rendition, but cost will go way up and efficiency will go way down so I doubt it will be common. And some stores are already adding UV LEDs to their lighting in order to make florescents really pop.
Edit: and a reference, the datasheet for the latest and greatest XHP50 LED: http://www.cree.com/~/media/Files/Cree/LED-Components-and-Mo...
Spectral charts are on page 11. Peak emission is at 445nm. Beyond 415nm there is nothing.
Cheaper LEDs will use a longer wavelength of blue, typically around 475nm.