Most of us are familiar with air, water, and land pollution, but did you know that light can also be a pollutant? Since Thomas Edison’s patent of the tungsten light bulb in 1906, artificial electric lighting has transformed our lives. But in the process, we have lost an important part of our human heritage: the night sky. Less than 100 years ago, most everyone could look up and see a spectacular starry night sky. Today 80% of Americans cannot see the Milky Way from their home. Over the last century, the increased, excessive and widespread use of artificial light at night has not only impaired our view of the universe but has adversely affected the Earth’s climate through unneeded energy consumption, disrupted numerous plants and animals that rely on Earth’s regular rhythm of night and day, and threatened human health and safety. Light pollution is a major contributor to the climate crisis. Large amounts of electricity are needed to generate light, and electricity is often produced by burning fossil fuels. Uncontrolled outdoor lighting wastes energy. As much as 50% of outdoor lighting is wasted, increasing greenhouse gas emissions, and contributing to climate change. Plants and animals depend on the daily cycle of light and dark to regulate reproduction, nourishment, sleep, and protection from predators. Scientific research has linked light pollution to negative and deadly outcomes for many creatures including amphibians, birds, mammals, insects, and plants. For example, some nocturnal birds use the moon and stars for navigation during their migrations; and they can become disoriented when flying through brightly lit areas. Female sea turtles shy away from areas with bright lights, which interrupts their nesting patterns. Newly hatched turtles are so drawn to lights that instead of heading to the ocean, they often end up on land instead. Research suggests that artificial light at night can negatively affect human health as well, increasing risks of obesity, depression, sleep disorders, diabetes, and breast cancer. Scientists have also established a link between light pollution and air pollution. Light from our cities can destroy nitrate radicals that form at night and help to cleanse the air. In addition to the negative economic, environmental and health impacts associated with light pollution, we are losing a precious natural resource: our nighttime environment. Outdoor lighting illuminates the sky, hiding the stars and changing how we experience the night. If you would like more information about light pollution and what we can do now to improve our nighttime environment, the International Dark-Sky Association is a good place to start. For a well-known columnist’s personal experience, see Dana Milbank, “I was busted by the light police. They had a point,” Washington Post, 5/5/23. Despite a century of uncontrolled outdoor lighting, there are ways to combat light pollution that will make a difference right away. The West Chester Green Team is addressing the problem of light pollution by creating a local Dark Skies Initiative. If you would like to learn more about the West Chester Dark Skies Initiative and help us publicize this important issue, please contact us.

Note: In 2022, several PA State Senators, including Carolyn Comitta form our area, filed a bill for the state to recognize Dark Sky Week in April 2022. The bill unfortunately did not reach the floor (see its history here); but let’s hope for success in another year.