What is one of the most pervasive types of pollution, yet is a rare type that completely disappears from the environment the moment we eliminate the source?
Polluted water stays polluted well past the time the contamination enters it. The same is true for air. Contaminated soil can stay that way for years on end, and various types of litter and other debris can outlive anyone reading these words today.
So what type of pollution disappears immediately after we stop adding more pollution?
To illustrate, here’s a story: One evening a few years ago the power went out. After stumbling around to find a flashlight, I stepped outside to see if it was just my house or if the whole neighborhood was dark. It turned out everyone’s lights were out, as well as the streetlights. As I turned back to go inside, something above me caught my eye. I looked up and saw a long cloud overhead stretching across the sky. But something was strange about it.
That wasn’t a cloud. It was the Milky Way! Yes, a “cloud”, but made of 400 billion stars.
It was so eye-catching because the instant the power had gone out, all the artificial light at night (ALAN) in the area stopped, leaving the Milky Way without competition from light pollution, both “sky glow” from light fixtures that shine a portion of their light upward and “light trespass,” where poorly shielded or poorly aimed fixtures shine light where it doesn’t belong.
Some ALAN is needed for our human communities to function, but much of the artificial light we create is wasteful, unnecessary, and damaging. It’s called light pollution — a serious problem that is increasing by about 10 percent per year.
Like most life on Earth, humans have a circadian rhythm — a sleep/wake pattern that is governed by the natural night/day cycle. We all know we need dark for a good night’s sleep — that’s why we turn the lamp off to go to bed! But what is really happening is the dark reinforces our circadian rhythm, which includes the body producing melatonin not only inducing sleep but also providing a variety of other important health benefits. Humans evolved in a world with night and day, and without lights, televisions, computer screens, and other ALAN that change the natural dark/light cycle.
Most non-human life on Earth, both animal and plant, also has a circadian rhythm. Each species has its own unique biochemical evolutionary adaptations, but the need for dark nights and light days is common. ALAN radically disrupts this cycle.
ALAN also impacts entire ecosystems. One example is nocturnal animals that sleep during the day and are active at night. Predators use light to hunt, and prey species use darkness as cover. ALAN changes this balance, which can have ripple effects on the entire ecosystem.
If we control ALAN and reduce light pollution, it is completely reasonable to expect that when we go outside on a moonless night almost anywhere, even near developed areas, we should be able to look up and see the Milky Way spilling across the sky.
But how? April 21-28 this year is International Dark Sky Week (idsw.darksky.org), an annual global event that celebrates the importance of the night and the fight against light pollution. This year the event was formally recognized locally by Santa Barbara County and the cities of both Goleta and Carpinteria. A key point repeated through the week’s events is that to reduce light pollution, as when making most positive changes, the place to start is at home.
There is an excellent online tool (tinyurl.com/homeALAN) that helps you evaluate your home’s present outdoor lighting and determine how you can make it more night sky and community friendly. This evaluation is built around five lighting principles:
1. Does the light serve a clear and necessary purpose?
2. Does the light fall only where it is needed?
3. Is the amount of light appropriate for the intended task?
4. Is the light connected to active controls?
5. Is the light source warm in color?
The website has brief descriptions and simple graphics explaining each of these principles.
We have a lot of traditions about how lighting is used and how it is expected to look. But after looking at lighting thoughtfully, the conclusion is often that many lights are excessively bright, redundant, aimed where they do nothing useful, or are just not the right light for the job. We pay for the electricity to run each light, so why wouldn’t we want to ensure each light is pulling its weight for us?
To help motivate you to take steps to reduce light pollution, on one of these warm spring evenings step outside, and while your eyes are adjusting, listen for the sounds that rely on the dark night – crickets, frogs, maybe an owl in the distance. Then look up and see how many stars are visible. Each light in our community that we change to point down or turn off with a timer or sensor will allow you to see a few more stars and will help our local wildlife.
Let’s get started!
