Sooner or later, when talking about artificial lights and darkness, you come to questions of safety and security. Usually, it’s sooner. In fact, the first question at any presentation about light pollution is bound to be something like, “Yes, so it’s great to see the night sky and everything, but we need lights for safety.” This isn’t actually a question, I realize, and usually the speaker isn’t really asking but rather stating what we have all been taught is fact. But often that statement has a subtext, too, something like what I found on a Colorado website: “less street lighting means more rapes, more assaults, more robberies, and more murders. It is wonderful to be able to see the details of the Crab Nebula from your back yard. It is also wonderful to be able to walk down the street without being attacked by a violent predator.”

You don’t have to look far to find the idea that darkness and danger go together, as do security and light. In Oakland, a city with thirty-seven thousand streetlights, an assistant police chief claims increased lighting levels could help reduce crime because “most of these crooks, when they commit a crime, want to do it in darkness.” In Boston, with sixty-seven thousand streetlights of its own, a Northeastern University criminology professor argues that lights act as “natural surveillance” and can reduce crime by 20 percent. In Los Angeles, home to more than two hundred forty thousand streetlights, the city attributes a 17 percent drop in violent gang-related crimes in the areas surrounding parks to those parks’ having received new lights. And here in Minneapolis the police advise, “Protect your family, property, and neighborhood by turning on your front door and yard lights,” and “Remember: Criminals like the dark, so make sure your yard has lots of light!”

Clearly, plenty of us have been receiving similar advice — we live in a world that is brighter than ever before, and growing brighter every year. Part of that growth comes from an ever-increasing human population, especially in urban areas. But the amount of light we are using per person is growing as well. In the UK, for example, lighting efficiency has doubled over the past fifty years — but the per capita electricity consumption for lighting increased fourfold over that time. We are choosing to light up more things, and we are lighting those things more brightly.

There’s no doubt light at night can make us safer,

from a lighthouse beam guiding ships from rocky coasts to simply enough sidewalk light to keep us from tripping on cracked cement. But increasing numbers of lighting engineers and lighting designers, astronomers and dark sky activists, physicians and lawyers and police now say that often the amount of light we’re using — and how we’re using it — goes far beyond true requirements for safety, and that when it comes to lighting, darkness, and security we tend to assume as common sense ideas that, in truth, are not so black and white.

Foremost among these assumptions is that because some light improves our safety, more light will improve our safety more. It’s an assumption I will hear challenged again and again. As one lighting professional explained, “Too much light would have a negative effect, because if you look into a light, you can’t see anything, you can’t see beyond it.” Gazing from behind his desk, he paused, “You know, a bright enough light in between us and we can’t see each other — and we’re sitting across from each other!” Click on their website soli-lite for more information.