What is Light Pollution?  

We most often notice light pollution, caused by excessive artificial light, at night when we try to view the stars in the night sky. The leading cause of light pollution is inefficient, and often unnecessary, lighting systems that put out excessive amounts of light, spilling it and the electricity used to generate it into the environment rather than focusing it on the objects and areas we want or need illuminated.

Common sources of light pollution include commercial and office building lighting (both interior and exterior), advertising, factories, illuminated sporting venues such as football fields and sports parks, and even streetlights and are a side effect of industrial civilization. Four main kinds of light pollution, including skyglow, glare, light trespass, and clutter are explained below.

Looking to our east, the light pollution from Cedar Park and Austin is hard to miss. This skyglow, or the brightening of the sky over inhabited areas, comes from both natural and human-made sources. Sky glow becomes a more visible effect of wasted light and energy when the weather is bad and more particles are present in the atmosphere to scatter light that is facing upward in all directions. Skyglow arises from the use of artificial light sources, including electrical, or, to a much lesser degree, gas lighting used for illumination and advertisement and from gas flares generated during various processes such as oil and gas refinery.
Here in Lago Vista, we are creating our own skyglow, particularly from our commercial businesses. As our population grows and more homes and other buildings are erected, the appearance of skyglow in our community will worsen unless we ensure our local ordinances are known and enforced, thereby reducing our contribution to this problem.


​Glare is another form of light pollution. When glare occurs, it is difficult to see because the light produces harsh shadows. Glare may even compromise the safety of a pedestrian or driver. We've likely all been blinded at night by an approaching vehicle either with very bright LED headlights or with its bright lights on. Think about how dramatically and for how long your ability to see is impaired when that happens.
One potential solution to glare is to shield the exterior lights on and around your home. In the top photograph on the right, notice how the glare from the light on the side of the house impairs the ability to see the person standing at the gate. Compare that to how clearly that same person standing in the same spot can be seen once the glare from the light is reduced.

​Some may consider light trespass to be the most annoying type of lightpollution yet perhaps the most difficult to define. Light trespass occurs when light is cast where it is not wanted. Determining when, where, and how much light is unwanted poses challenges and is often subjective because where one person may think certain light trespass is not problematic, another person may think the same light trespass is very problematic. One example of light trespass is when light from a neighbor’s floodlight enters a window of your home and illuminates an indoor area such as a bedroom or living room.
Light trespass could easily be significantly reduced if lights are properly aimed or if a shield is placed on the luminaire, particularly with floodlights. Even using a motion detector or a timer on certain outdoor lights and pointing them downward  would make a marked difference. Purchasing International Dark-Sky Association (IDA) approved light fixtures. Most simply, you can also turn your lights off when you aren’t using them.
Clutter light pollution comes from bright, excessive groupings of light sources that collectively generate large amounts of light at night. This type of lighting most commonly applies to municipal lighting such as streetlights. Streetlights can add to driver distraction which may result in severe accidents.
 
Using full cutoff lights, not to be confused with fully shielded lights which are different, is one way to reduce light clutter. Full cutoff lights do not emit light directly upward. They also comply with glare requirements which typically limit the intensity of light emitted from the luminaire in the region between 80° and 90°.
Full cutoff lights force the light that is emitted to shine down onto the ground where it is needed and prevent the light from shining thoughtlessly across property lines or wastefully up into the night sky. This not only reduces the light pollution in the night sky but also for nearby houses because the light is concentrated on specific objects and locations where it is needed without adversely affecting the surrounding environment.

How Can I Help?

Light pollution is reversible. You can help make a difference. Some simple actions you can take include:
  • Learn more. One way to do so is to review our local lighting ordinances here in Lago Vista;
  • Only use lighting when and where it’s needed;
  • Install motion detector lights and timers on outdoor lighting such as floodlights if safety is a concern;
  • Properly shield outdoor lights or invest in full cutoff lights;
  • Keep your blinds closed at night to keep light inside;
  • Help spread the word to your family and friends and encourage them to do the same. Others may not know or understand a lot about light pollution or the negative effects of artificial light at night; and
  • Consider joining the Lago Vista Starry Skies committee. We are always looking for interested and motivated members to help us educate others and conduct community outreach.