What is Light Pollution?

Artificial Light at Night (ALAN) has revolutionized how we live, work, and play.  It enhances our modern lives, and few of us can imagine life without ample lighting available at the flip of a switch.  ALAN is a tool that provides many benefits, but as with any tool we need to pick the right tool for the job, use it properly, and put it away when we’re done.  LED lights are an engineering marvel -they’re efficient, long lasting, and come in a variety of hues, or Color Temperatures, from invigorating blue-white ‘daylight’ bulbs to cozy amber ‘warm white’ bulbs.  But there can also be a dark side lighting.  Excessive or inappropriate lighting, or light pollution, can cause real harm -harm to our health, to our environment, and to our communities.  In this series of short articles, we’ll learn what light pollution is, how it impacts our health and the environment, and learn some simple things we can do in our homes, businesses, and communities to help us enjoy light’s benefits will avoiding its potential harms.

There are 4 main categories of light pollution: glare, trespass, clutter, and skyglow.  Glare is the most familiar -it occurs when a light shines directly in your eyes.  Trespass occurs when a light you don’t control shines onto your property or onto (or into) your home.  Clutter is the accumulation of an excessive number of glaring lights.  Skyglow occurs when light shines upward, or is reflected upward into the sky.  The level of potential harm from each of these types of pollution is affected by a few key factors: How bright the light is (how many lumens), how much blue light it emits (Color Temperature, measured in Kelvins), how long the light is on each night, and how well the light is shielded and aimed.

To limit light pollution and use light to its greatest benefit, start with the 5 Principles of Responsible Outdoor Lighting: 

  1. Light should be useful.  If it’s not currently serving a purpose turn it off.  
  2. Light should be targeted.  Put light only where you want it -use shielding to prevent glare, clutter, and skyglow.  
  3. Use the right amount.  Pick a light that’s as bright as needed, but no brighter.  Recall that light is a tool -pick the right tool for the job.  
  4. Control it.  Use active controls such as timers, motion detectors, and dimmers to provide light only when its needed.  LEDs are instant-on and dimmable, making them a great choice for putting you in control of your lighting. 
  5. Pick warm colors.  Blue-bright lights disrupt our circadian rhythm, which can lead to a range of health consequences.  Lumen-for-lumen, it also creates more skyglow, which wastes light and harms the environment.
Here are three simple Go-Do’s. 
  1. For your home: Turn off unused lights.
  2. In your neighborhood: talk to your neighbors about lights that shine into your yard or home.
  3. In your community: ask businesses to turn off interior lights that shine out their windows when the business is closed.

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