Our website has detected that you are using a browser that will prevent you from accessing certain features. An upgrade is recommended to experience the full features of the MKCA website. Use the links below to upgrade your exisiting browser.

Future Streets are Mostly Blue

No Sleep City: New York After Dark

When asked to contemplate the idea of escape from the city, we went immediately to the search for peace and quiet in The City That Doesn’t Sleep. That sleeplessness is a real thing. We took a look at 311 complaint data, from 2010 until the present day, mapping all of the complaints that took place between the hours of 12-6am, when we should all be in bed. Of course, most 311 complaints are about noise, but the resulting visualization shows a city that is inflamed and pulsating in the middle of the night. It seems that no one can get to sleep in this town.

We wondered about that pulsation and how it might relate to our ongoing fascination with the electromagnetic environment of the city. If we look at a satellite image of that city in the middle of the night, we see it fully incandescent, glowing. And the color of that glow? That’s the light of our built environment: buildings, street lighting, and the light from our screens. And it’s changing.

As we speak, about 250,000 sodium halide streetlights in New York City are being replaced with LED, which tend to be significantly more efficient and also give off a cleaner, more illuminating light. It’s a $76.5 million project and if projections bear out, will save the city about $14 million in maintenance and energy annually.

That new lighting is mostly on the blue end of the light spectrum. And there’s a reason for that. Dark-adapted (nighttime) eyes are much more sensitive to shorter (bluer) wavelengths than light adapted (daytime) eyes. Therefore, a light source producing more blue light will tend to appear brighter to the dark-adapted eye. Not only is blue LED dramatically more energy efficient than other types of lighting, it is also used for high speed networking, data storage, smartphones, and water purification. In fact, it is so significant that the inventors of blue LED were awarded the 2014 Nobel Prize in Physics. By blue, we’re talking about 350-530 nanometers in wavelength. And it turns out that this is a rather controversial little area of the spectrum.

The American Medical Association House of Delegates in June of 2012 adopted a policy statement on nighttime lighting and human health. The report cites evidence that nighttime electric light can disrupt circadian rhythms in humans and documents the rapidly advancing understanding of how that disruption affects a number of different aspects of physiology with direct links to human health, such as cell cycle regulation, DNA damage response, and metabolism.
The AMA report cites evidence establishing strong linkages between circadian disruption and melatonin suppression, and a correlation with various carcinogenic effects, especially breast cancer. Other conditions that may be exacerbated by circadian disruption include obesity, diabetes, depression and mood disorders, and reproductive problems.
At 430-510 nanometers, we find the wavelength that has been shown to have the greatest disruptive effect on circadian rhythms. It’s not just the source but also its attendant illumination in the atmosphere that has prompted a great deal of concern. We looked into the growing citizen science community dedicated to recording and reporting on the presence and also the absence of light pollution. Much of our data comes from these sources.
We took recent high resolution satellite imagery from the Suomi National Polar Orbiting Partnership Satellite showing the nighttime illumination of the planet, and correlated it against other mappings showing gradations of the Bortle Scale, is a nine-level numeric scale that measures the night sky’s brightness of a particular location. It quantifies the astronomical observability of celestial objects and the interference caused by light pollution.
From an instrumentation standpoint, blue-rich white light sources tend to produce 15-20% more sky glow as compared to incandescent sodium light sources. But due to the eye’s increased sensitivity to blue light at lower levels, the visual brightness of sky glow produced by bluish LED can appear three to five times brighter than high pressure sodium, and up to 15 times brighter compared to low pressure sodium, which means that even as we gaze sleeplessly into the dark sky, increasingly we’re also losing the stars.


An escape from the electromagnetic noise of the city into darkness, presented  by Michael Chen at the Van Alen Institute, part of Else/Where: Escape and the Urban Landscape.