Light Pollution is the human-made alteration of outdoor light levels from those occurring naturally.
It is a side effect of industrial civilization and can result from building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues.
Glare - excessive brightness that causes visual discomfort
Sky glow - 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
Lights Out, Carrollton!
Texas is an essential corridor for migratory birds, with millions soaring across our Lone Star skies every spring and fall. Bird-building collisions are a serious hazard for migrating birds. Did you know that over 90% of bird collisions and injuries happen on low-rise or residential buildings? You can make a difference in your home by marking your windows to create visual barriers and turning off non-essential lights at night during peak migration season!
Spring: March 1-June 15, peak period from April 19-May 7.
Fall: August 15-November 30, peak period from September 5-October 29.
Why do birds crash into windows? There are two main types of window collisions: daytime and nighttime. In daylight, birds crash into windows because they see reflections of vegetation or see through the glass to potted plants or vegetation on the other side. At night, nocturnal migrants crash because they fly into lighted windows. Visual barriers on your windows at home or work will help birds avoid deadly collisions. The ideal marking should be spaced 2 inches apart across the entire surface of the glass. The marking can be paint, decal stickers, dot patterns, tape - you can even get creative with it and paint seasonal window murals to protect our birds!
Everything in an ecosystem is connected, and altering natural conditions through the use of artificial lights can have negative impacts on a wide range of species. Studies evaluating the impact of artificial lights on wildlife have indicated detrimental changes to nocturnal animals that rely on the nighttime environment, as well as prey species which use darkness as cover. Sea turtle hatchlings naturally find the sea by following the bright horizon over the ocean, but they can be drawn away by the glow of artificial lights. Migratory birds depend on cues from seasonal schedules, and artificial lights can cause them to migrate too early or too late and miss ideal climate conditions, or worse, collide with over-lit buildings and towers. Insects play an important ecological role and are relied on by many species for food or pollination, and population declines due to fatal attraction to artificial light glare can affect the food web in unanticipated ways.
Help protect wildlife from the impact of artificial lights by using responsible lighting practices.
Learn more about how you can use responsible lighting practices to prevent light pollution here.
Human Health
Many species, including humans, need darkness to survive and thrive. Like most life on Earth, humans adhere to a circadian rhythm — our biological clock — a sleep-wake pattern that is governed by the natural day/night cycle. This cycle is largely influenced by photoreceptors in the eye that are more sensitive to blue wavelengths of light. It’s important for every human to experience outdoor lighting during the day and minimize the amount of light entering their eyes at night to maintain a good circadian cycle. Artificial light at night can, unfortunately, disrupt that cycle.
Many studies have shown that exposure to artificial light at night negatively affects human health, including increased risk for:
Sleep disorders
Depression
Obesity
Diabetes
Heart disease
Cancer
According to the American Medical Association, “It is estimated that white LED lamps have five times greater impact on circadian sleep rhythms than conventional street lamps. Recent large surveys found that brighter residential nighttime lighting is associated with reduced sleep times, dissatisfaction with sleep quality, excessive sleepiness, impaired daytime functioning and obesity.”
Today’s best practice for nighttime lighting is to minimize your exposure to light, and especially to blue light. When you’re home at night, use dimmers and lower-CCT light bulbs, and utilize color temperature apps that adapt your electronic screens to the time of day — “cool” appearing light during the day and “warm” appearing light at night.
Glare from poorly shielded outdoor lighting also harms your health because it decreases vision by reducing contrast. This limits our ability to see potential dangers at night. Aging eyes are especially affected.
You can do your part to reduce glare by using shielded fixtures and dimming the light levels to only what is required. Often, outdoor light fixtures produce more light than is necessary, and dimming them to more appropriate levels reduces glare and saves energy.
Learn more about the impacts of light pollution on human health here.
Energy and Climate Change
Quality lighting design reduces energy use and therefore energy dependence. It also reduces carbon emissions, saves money, and allows us to enjoy the night sky.
LEDs and compact fluorescents (CFLs) can help reduce energy use and protect the environment, but only warm-white bulbs should be used. Learn more about LEDs and correlated color temperature (CCT) from our LED Practical Guide.
Dimmers, motion sensors, and timers can help to reduce average illumination levels and save even more energy.
Installing quality outdoor lighting could cut energy use by 60 to 70 percent, save billions of dollars, and cut carbon emissions.
Outdoor lighting should be fully shielded and direct light down where it is needed, not into the sky.
Fully shielded fixtures can provide the same level of illumination on the ground as unshielded ones, but with less energy and cost.
Unnecessary indoor lighting – particularly in empty office buildings at night – should be turned off, preventing leakage of that light into the night sky.
Crime and Safety
It is innately human to be afraid of the dark. It's a completely natural response based on our biological instincts. When young kids have nightmares, we turn on a night light to make them feel better. Having lots of bright lights on makes us feel safer, and that has been reflected in studies relating light levels to crime and safety. Studies conducted on the effect of increased lighting on crime and safety primarily show that people feel safer when there is more light, however, data reflecting changes in crime statistics has been inconclusive so far.
We are not advocating for no lighting on our streets and in our neighborhoods; we support better lighting. Responsible lighting practices allow us to feel safe and to have good visibility at night without compromising our view of the sky.
Night Sky Heritage
The nighttime environment is a precious natural resource for all life on Earth, but the glow of uncontrolled outdoor lighting has hidden the stars and changed our perception of the night.
Until recently, our ancestors experienced a sky brimming with stars — a night sky that inspired science, religion, philosophy, art, and literature, including some of Shakespeare’s most famous sonnets. Experiencing the night sky provides perspective and inspiration, and leads us to reflect on our humanity and place in the universe. The history of scientific discovery and even human curiosity itself is indebted to the natural night sky.
Without the natural night sky we could not have:
Navigated the globe
Walked on the Moon
Learned of our expanding universe
Discovered that humans are made of stardust
The natural night sky is our common and universal heritage, yet it’s rapidly becoming unknown to the newest generations. How many stars can you see from your home? How far do you have to travel to get to an area dark enough to see lots of stars?
Let's do our part to protect our Night Sky Heritage!
Be A Star Award
Be A Star Award
The award is a self-assessment where you determine if your property follows the Five Principles of Responsible Outdoor Lighting. Landowners earning the award may select the recognition items of their choice.
The award is a self-assessment where you determine if your property follows the Five Principles of Responsible Outdoor Lighting. Landowners earning the award may select the recognition items of their choice.
