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CIty at night with light pollution

Why should your municipality be concerned about light pollution?

1. Energy waste and carbon emissions

In an average year in the U.S. alone, outdoor lighting uses about 380 terawatt-hours of energy, mostly to illuminate streets and parking lots. That’s enough energy to meet New York City’s total electricity needs for two years!

DarkSky estimates that at least 30 percent of all outdoor lighting in the U.S. alone is wasted, mostly by lights that aren’t shielded. That adds up to $3.3 billion and the release of 21 million tons of carbon dioxide per year. To offset all that carbon dioxide, we’d have to plant 875 million trees annually.

Learn more about the effects of light pollution on Energy and climate change.

2. Negative effects on wildlife

Numerous studies have shown that artificial light at night has numerous negative and deadly effects on many types of wildlife, including birds, amphibians, insects, and mammals.

3. What about crime and safety?

There is no clear scientific evidence showing that increased outdoor lighting deters crime. While brighter lighting may make us feel safer, poor outdoor lighting can actually reduce our personal safety. A study conducted by the city of Chicago found a correlation between increased crime and brightly lit alleyways. A study prepared by the U.S. National Institute of Justice concluded: “We can have very little confidence that improved lighting prevents crime.”

In fact, glare from bright lights makes it difficult to see into shadowy areas, where people can hide. Some crimes, such as vandalism and graffiti, thrive on lighting.

Glare can also be dangerous to pedestrians and drivers. It shines into our eyes and diminishes our ability to see in low-light conditions.

A problem that has simple solutions

The good news is that your municipality can have it all — environmentally responsible lighting that helps keep citizens safe. When lighting is shielded, it’s directed down on the ground where it’s needed, which minimizes glare, light pollution, and carbon emissions and saves money.  DarkSky has adopted the Five Principles for Responsible Outdoor Lighting to give overall guidance on how to effectively reduce light pollution while simultaneously improving lighting quality and public safety.

Why outdoor lighting ordinances matter

Outdoor lighting ordinances or codes are a great tool for ensuring that municipalities implement good, safe outdoor lighting. A well-written ordinance, with proper lighting installed, will save the public money and increase safety.

In 2011, DarkSky, in collaboration with the Illuminating Engineering Society (IES), created the Model Lighting Ordinance (MLO) to make it easier for municipalities to adopt good lighting policies. Although the MLO is no longer being updated, it offers useful guidance for cities to consider when developing their own approach to lighting.

LEDs and outdoor lighting

Many municipalities are replacing older, conventional lighting systems with new, energy-efficient, light-emitting diodes (LEDs). However, energy efficiency is just one piece of the puzzle in improving outdoor lighting at night.

Cities like Tucson, Arizona, have successfully upgraded their lighting systems and achieved energy savings and reductions in light pollution. By following the Five Principles for Responsible Outdoor Lighting, cities can select outdoor lighting that increases energy and cost savings, enhances safety and security, protects wildlife, and preserves the nighttime environment.

We strongly encourage municipalities to give equal weight to energy conservation and light pollution reductions when considering a new outdoor lighting system.