By Brad Hopkins and Chris Clark

[from the Commercial Record, April 7, 2022]

There is no clear evidence that using more outdoor lighting leads to less crime. It may make us feel safer, but we are probably not really safer. The truth is that bad outdoor lighting can decrease safety by making victims and property easier to see. A recent study showed that in one place crime actually increased after it was more brightly lit.

Dark-sky-friendly lighting does not necessarily mean dark ground. The goal is to direct lighting where it’s needed. We want outdoor lighting to increase safety and security at night and help us see clearly, but lights that are too bright can have the opposite effect. The glare from bright lights can make things less safe. Glare shines into our eyes and constricts our pupils, making it more difficult for our eyes to adjust to low-light conditions. It can even temporarily blind us.

Below, at left, glare keeps us from seeing who’s at the gate (photos by George Fleenor)

On streets and highways, poor lighting can create unsafe driving conditions and lead to traffic accidents. Many people are temporarily blinded by glare from streetlights and signs that are too bright, and this is even more of a problem for older folks. A study published in 2015 found that streetlights in one city didn’t prevent accidents or crime, but they did cost a lot of money. The City of Tucson experimented with reducing street light brightness by two-thirds. The changes made for less glare and they were barely noticed. The city received no comments or complaints and there was no negative effect on public safety. 

Cities and businesses often light parking lots and other public places to improve safety. However, lighting that is too bright or poorly aimed can actually attract criminals and allow them to more clearly see what they’re doing. Overly bright lighting creates a sharp contrast between light and dark. A spot outside of the area that’s lit can be very difficult to see, if not impossible.

Effective lighting helps people be safe, not just feel safe. We can have a safe environment and keep the night natural. Cities and towns should regulate the types of lighting they use. Here are some simple guidelines:

• Have fully shielded fixtures shine down, eliminating glare and contrasts.
• Only use lights when and where needed; timers and dimmers help a great deal.
• When installing security lighting, use motion sensors.
• Use low-wattage bulbs. Too much light impairs vision and wastes money.

Dark Sky Action Item 4: Drive around your town at night and pay attention to the street lights. Do they shine in your eyes? Would they be just as helpful if they were shielded?

Next week: “Nighttime Lights Threaten Human Health”