Less than 100 years ago, everyone could look up and see a spectacular starry night sky. Now, millions of children across the globe will never experience the Milky Way where they live. The increased and widespread use of artificial light at night is not only impairing our view of the universe, but it is also adversely affecting our environment, our safety, our energy consumption and our health.

What is Light Pollution?

Most of us are familiar with air, water, and land pollution, but did you know that light can also be a pollutant? The inappropriate or excessive use of artificial light – known as light pollution – can have serious environmental consequences for humans, wildlife, and our climate. Components of light pollution include:
  • Glare – excessive brightness that causes visual discomfort.
  • Skyglow – brightening of the night sky over inhabited areas.
  • Light trespass – light falling where it is not intended or needed.
  • Clutter – bright, confusing and excessive groupings of light sources
The infographic side illustrates the different components of light pollution and what “good” lighting looks like. (Image by Anezka Gocova, in “The Night Issue”, Alternatives Journal 39:5 (2013). Click to enlarge.
Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues. The fact is that much outdoor lighting used at night is inefficient, overly bright, poorly targeted, improperly shielded, and, in many cases, completely unnecessary. This light, and the electricity used to create it, is being wasted by spilling it into the sky, rather than focusing it on the actual objects and areas that people want illuminating.

How Bad is Light Pollution?

With much of the Earth’s population living under light-polluted skies, over lighting is an international concern. If you live in an urban or suburban area all you have to do to see this type of pollution is go outside at night and look up at the sky. According to the 2016 groundbreaking “World Atlas of Artificial Night Sky Brightness,” 80 per cent of the world’s population lives under skyglow. In the United States and Europe, 99 per cent of the public can’t experience a natural night! Before and during the 2003 Northeast blackout, a massive power outage affected 55 million people. Photo by of Todd Carlson If you want to find out how bad light pollution is where you live, Google Earth users can download an overlay also created from the “World Atlas” data.
NASA Blue Marble Navigator
Globe at Night light pollution map
NASA Blue Marble Navigator
Globe at Night light pollution map

Effects of light pollution

Effects

For three billion years, life on Earth existed in a rhythm of light and dark that was created solely by the illumination of the Sun, Moon and stars. Now, artificial lights overpower the darkness and our cities glow at night, disrupting the natural day-night pattern and shifting the delicate balance of our environment. The negative effects of the loss of this inspirational natural resource might seem intangible. But a growing body of evidence links the brightening night sky directly to measurable negative impacts including:
➥Increasing energy consumption
➥Disrupting the ecosystem and wildlife
➥Harming human health
➥Effecting crime and safety
Light pollution affects every citizen. Fortunately, the concern about light pollution is rising dramatically. A growing number of scientists, homeowners, environmental groups, and civic leaders are taking action to restore the natural night. Each of us can implement practical solutions to combat light pollution locally, nationally, and internationally.