When I lay my head down at night, if the blackout curtains are a little off center, somehow the glaring light from a street lamp makes a straight line right to my eyes. Without the curtains, my bedroom would be brighter than daylight, with a flooding glow from the street lights and nearby apartment lights. These lights aren’t only making me get up to adjust the curtains; they are also pollution to our environment.
That’s right, I said pollution, light pollution. Normally when we think of pollution we think of trash, chemicals or sea turtles stuck in plastic six-pack rings. But light pollution is artificial outdoor light that negatively impacts our ecosystems and human health. Light at night affects our circadian clock and our sleep hormone melatonin. It can lead to sleep disorders, and new research is investigating a link between light pollution and breast cancer.
Since the invention of the light bulb, we have been able to light up our dark evenings and increasingly make nighttime brighter. Excessive outdoor nightlights burn energy, disrupt wildlife and ecosystems, and interfere with our ability to see the stars. Earlier in August, we had the opportunity to view the spectacular Perseid Meteor shower, a sky full of shooting stars, but it was recommended to get out into the country, hours from the city, to get a clear view. The big glow effect of a city from a distance is called sky glow, which is caused by reflected and upward directed light. Simply shielding light downwards can reduce light pollution.
We’ve come a long way since incandescent light bulbs, which use a lot of energy. Light bulbs used in today’s world, such as compact fluorescent (CFL), light-emitting diodes (LED) and high-pressure sodium (HPS) differ in their energy usage, lifespan and output of wavelengths of light. Recently consumers and cities have been changing to energy efficient LED lights, yet studies are finding they come with an ecologic drawback. In a published study (Pawson and Bader, 2014) done in New Zealand, scientists compared the use of LED and HPS lightbulbs (often used for street lights) and found on average LED lights captured 48 percent more insects than HPS lights. The study stated that LED use may exacerbate ecological impacts and urged for collaboration between ecologists and electrical engineers to minimize potential effects.
Light pollution also affects other plants and animals, even here in Dallas. Light pollution can prevent trees from adjusting to seasons, alter animal behaviors and disrupt breeding cycles. The Trinity River Corridor is a light pollution refuge for much of our wildlife. Take a look at the light pollution map of Dallas at LightPollutionMap.info with data at the Earth Observation Group and NOAA National Geophysical Data Center. Even though Dallas is submersed in high-density light pollution, you can easily make out the Trinity River Corridor. As we develop the corridor into a usable green space and possible site of more roads, we should place a high priority on its hard-to-see importance as a nocturnal that sanctuary for urban wildlife.
Light pollution increases more each year and can even be seen from space. Mapping and understanding where light pollution is and comparing ecology in subsequent years and from areas with no light pollution, are important for maintaining a healthy environment. Cities at Night (citiesatnight.org) is a project to map light pollution in cities around the world using photographs from the International Space Station. Their goal is to create a Google Maps style map by having the general public (like you) view beautiful space pictures and to help classify and calibrate images through fun-to-use apps. This will produce new data made available to scientists to improve light pollution research and ultimately help cites choose cost effective, energy efficient and ecologically improved lighting.
But the light that went up outside my bedroom was in response to an attack on an elderly person outside a nearby restaurant. The light pollution in the city is a complicated issue, but preserving pockets of less light, shielding upward light and engineering low ecologic damaging light bulbs will maintain the health of our ecosystems while also keeping our city safe.
As seen in the Katy Trail Weekly.