Street Lighting, Blue Light, and Light at Night

LED street lighting is frequently in the news these days. But due to the complexity of the underlying science – which encompasses everything from spectral power distribution to Lambertian reflectance to melanopic lux – the coverage sometimes serves to underscore how easy it can be for those who aren’t experts in the topics at hand to get the facts wrong and draw erroneous conclusions.

Although the initial commotion has calmed, a continuing succession of news stories generated bythe American Medical Association’s (AMA) community guidance on street lighting has kept the topic of LED street lighting and its potential effects on health and the environment in the public’s mind. As discussion of these issues spread, so did many misperceptions and mischaracterizations of the technical information, with the difference between what had and had not been scientifically established often blurred.

An important study on light at night, published in the November 2017 issue of Science Advances, has also generated a number of news stories that draw unwarranted conclusions about LED street lighting.

DOE has assembled a variety of resources on these topics, to provide accurate, in-depth information that clarifies the current state of scientific understanding.

IES Position Statement on Street Lighting

The Illuminating Engineering Society of North America (IES) has issued a position statement that offers additional valuable, science-based information on the human and environmental effects of LED street lighting.

DOE Research

DOE has published a study conducted by Pacific Northwest National Laboratory, An Investigation of LED Street Lighting’s Impact on Sky Glow. The study examines the expected contributions to sky glow from converting high-pressure sodium (HPS) street lighting to broader-spectrum (i.e., white light) sources, with specific focus on LEDs, and presents the contributions in a manner relative to HPS baseline conditions. These conditions represent typical conversions in the U.S. and include changes in spectral power distribution (SPD), percent uplight, and lumen output.

In addition, a new DOE-funded research project conducted by Virginia Polytechnic Institute and State University will investigate the health impacts of outdoor lighting by providing key experimental data on the effects of roadway lighting on drivers, pedestrians, and residences that experience light trespass. Through a highly controlled experimental test plan aimed at identifying threshold effects for different correlated color temperatures (CCTs), the project will provide insight into the conversion of outdoor lighting systems to SSL and will allow for science-based, informed decision‐making.