Too Much Light in the Night: Light Pollution in Ultras
You’ve probably heard that we are losing our night skies. The overlighting of our cities is literally blinding us to the nightly spectacle that unfolds above us. Some communities are fighting to take back our night skies through prescient ordinances that, ironically, cost residents and developers less in the long run. Prohibiting upward-pointing lighting, practicing “dark space” security, and installing indirect light fixtures improve safety, increase overall visibility, and better achieve what lighting is supposed to do, all at lesser cost.
Meantime, in ultras where participants run through the night, often in places where the darkness of the skies is a main attraction, the problem of overlighting is growing--rapidly. In the 1500 miles of trail ultras I have run in the last two years, which involved ten full nights of running, I have lost count of how many times I have been blinded or dizzied by overlighting and poor light management.
Any white light will destroy your night vision, that which uses the very sensitive but low-resolution, non-color rods in your retina. In such an environment you become completely dependent on your cone cells. This will give you full detail and color vision—in, ironically, a narrow cone of light as far as your headlamp can cast. For bright headlamps this maxes out perhaps 200 feet ahead of you.
This may sound like a lot, but in the process of creating your little bubble of sun, you shut out 99.9% of vision of anything else out there, including in your periphery. 0.1% for 99.9% is a pretty bad bargain. Trees, peaks, meadows, sky—all disappear, much like when you are driving into the sun and can see nothing else (including traffic).
Other colors of light besides white, usually red or green, can preserve much of your retinal rod low-light vision. As an Army paratrooper we only use red or green light during night operations. I thus learned early that the least light is the best light. In a combat zone a light is a target. Moreover, bright light actually impedes your vision, blinding you to threats (or, if you are jumping out of an airplane at night, the ground—you would be amazed how well you can see the ground rising up to meet you on a night jump when your vision is properly adjusted to the dark). So I have become very comfortable with using red or green lights to illuminate only what I need (the trail ten feet in front of me and my watch face). In some instances, such as during fast races (like 100 milers) where downhill speed is at a premium, I will use a white light. But for most runners it simply is not necessary.
You may ask why anyone would reduce their light to red or no light at all. Going back to the way your eye works, when you reduce white light, more rod cells kick in, allowing you to see the vistas and the sky that presumably you paid so much to run in and under. This means you no longer remain a prisoner of The Dreaded Light Cone. You see horizons, you see constellations, you see wildlife, you see satellites, you see meteors, you see the milky way.
It can be even better. During the Moab 240, in the two hours before dawn, while running in red light, I saw the Zodiacal Light, a column of cosmic light caused by a interplanetary dust cloud only visible predawn in the fall and postdusk in the spring. The cloud is in the path of the Earth’s orbit and catches sunlight, reflected back to the predawn or postdusk Earth. It is incredibly faint, and only visible in the darkest, nonurban skies.
There are two rebuttals to reducing white light. (1) I need a bright light in order to resolve trail obstacles, and (2) who cares if I blind myself, it’s my own business.
For (1), I go back to the days when I would bomb down Alta Dry Fork during Wasatch with a AAA mini mag light. In other words, save your tears. When transiting a rock pile light angle is far more important than light brightness. A handheld will get the light source away from your eyes and therefore increase dramatically your stereoscopic vision, casting shadows behind obstacles and allowing you to see them in 3D. For downhill and flat fell running, moving the light to your hand will allow you a 90% decrease in brightness yet still efficiently light.
Some may argue that a handheld won’t work for them because they are using poles, but if you are using poles, you are not going fast enough to need that much light. (If you doubt this, try running a rough trail downhill with poles and without, timing yourself. This is fodder for another article, but trust me—you will be going slower with poles). Also, if you are using poles or otherwise despise a handheld, a belly or belt mount will also increase your lighting efficiency. Lower the light, lower the lumens.
For climbing and slow flats and even slow downs (typical for most of us after mile 70), a good red or green light, a meter off the ground, is often enough light for any terrain.
As for (2), my lighting is my business: No, it’s not. If you think that way, then you must be the driver who leaves his brights on when in the oncoming lane. There is a reason such conduct is illegal. While ultrarunners are not going so fast as to pose the traffic risk that is now outlawed with no-brights law, the concept is the same—it can be dangerous, and is simply rude. The rules of politeness are simple: use the least lighting you need for the task at hand, and if someone within the cast of your light is using less light than you, contain your light so as to not blind them. If that person is using red light or no light at all, you must use best efforts to not illuminate them AT ALL. This means lowering your light level, moving your light into your hand, or shading your light until you pass that runner. This is just common decency and sense.
Going back to the Zodiacal Light in the Mob 240--there is only one reason I got to see it. First, I had preserved my night vision. Second, I had to escape the reach of 300 Lumen headlamps being panned and jiggled by runners behind me, who had absolutely no reason to use that much light in that manner on a—wait for it—utterly empty PAVED highway straight out of Close Encounters of the Third Kind. Once I escaped the walking dance party I was able to see what I paid for, both in sweat and in dollars.
It should not be this way. There is an ethos to ultrarunning. Pick up your trash. Bury your poop. Be nice. And don’t blind other runners or ruin their views.
Part of the fault for this problem lies at the feet of manufacturers, who are building ever brighter lights, at ever higher costs, with no effort made to educate consumers about the dangers and inconsiderateness of overlighting (and the proper use and placement of light, including how to dim a light from its max rating). More lighting means more light sales, and more batteries and battery packs sold. This vicious pattern is nothing new, with runners pushing for gear they likely don’t need and manufacturers creating new “needs.”
But we need not feed the beast. Many of these new uberlights have lower settings, with their brightest settings being available in case you are being chased by a moose (yup, done that) or are on a short, fast training run (yup, I do that). The lower settings will save your battery life and are still efficient lighting. A light made for a quick downhill bomb of Mailbox after work is not the same light, at the same setting, that you need at mile 90 of a hundred. If you need the latest and greatest, know its place, know YOUR place, learn how to use it, and TURN IT DOWN.
You can be polite, save other runners’ experience, and save your precious battery life, by remembering:
1. Use only as much light as you need to safely move on the trail.
2. Adjust your lighting when encountering other runners by maintaining your light in front and down—minimal panning.
3. Do NOT EVER shine your light in another runner’s eyes.
4. When passing lower your light to the level of the passed runner’s light, or shield your light, until you have passed.
5. Try physically changing the position of your light for maximum efficiency (1 meter from ground).
6. Do NOT pan or sweep your light, or point your light up or at runners in the distance (even from behind), unless safety demands (isolating wildlife or other hazard).
7. Headlamps OFF in aid stations. This year at a race my crew watched as a pacer single handedly blinded three aid station workers with the car headlamp on her head until a runner cried, “Light off!” and saved the day (night).
It’s too bad that any guidelines like this should be necessary, but sadly I have seen every single one of these principles violated dozens of times in the last couple of years. If folks would be mindful of night vision and common sense they wouldn’t be necessary. Hopefully they never become “rules,” since rules kind of suck.
But seriously. Use some freaking common sense. And the next time you watch the space station cross the terminator and glow white, then orange, then red, then disappear, send me a PM and tell me all about it.
Run gently out there. In the dark.
