Illuminating the Path: Western Planners and Light Pollution
by Leo Smith
Introduction
Light pollution is a growing concern across the globe, with significant consequences for both the environment and human health. In the American West, a region known for its vast, unspoiled landscapes, light pollution threatens ecosystems, disrupts wildlife behavior, and obscures the night sky, which is cherished by both residents and visitors. The uncontrolled spread of artificial light affects everything from the health of local communities to the survival of species dependent on natural nighttime cycles. As these impacts become more widely recognized, municipalities are beginning to adopt policies to mitigate light pollution and protect both the environment and quality of life for their residents.
Understanding Light Pollution
To understand light pollution, it is important to understand key terms:
Light pollution refers to “any adverse or unintended effect of the use of artificial light at night, including sky glow, glare, light trespass, light clutter, decreased visibility at night, and energy waste (International Dark-Sky Association).” Light pollution also includes broader issues like energy waste, as improperly designed lighting systems often consume unnecessary amounts of power. In response to these concerns, the American Medical Association (AMA) has classified light pollution as a potential carcinogen, urging municipalities to adopt strategies that shield outdoor lighting and reduce excessive blue wavelengths emitted by LEDs (preferably below 3000K).
Glare refers to excessive brightness that causes visual discomfort and impairs visibility.
Light Trespass occurs when light spills over into areas where it is not needed, such as into homes or onto neighboring properties.
Clutter consists of excessive clusters of light sources that are redundant, overly bright and confusing.
Skyglow is the brightening of the night sky caused by artificial light, particularly from urban areas, which makes it difficult to see celestial bodies.
The Adverse Effects of Light Pollution
Light pollution manifests in several ways, including glare, light trespass, and skyglow. It disrupts ecosystems, human health, and the beauty of the natural world.
1. Ecosystem Disruption The most obvious impact of light pollution in the West is on wildlife, particularly nocturnal species. Many animals, including migratory birds, insects, and bats, rely on natural darkness for navigation, hunting, and reproduction. Bright artificial lights disrupt these natural behaviors, often leading to disorientation, increased predation, fatal collisions, and long-term population decline. For example, bright city lights can confuse migratory birds, which rely on the stars for navigation, causing them to become disoriented and fatally fly into buildings.
2. Human Health Impacts Light pollution also affects human health, particularly by interfering with circadian rhythms. Exposure to artificial light at night can disrupt sleep patterns, increase levels of stress hormones, and contribute to a variety of health issues, including insomnia and increased risks for certain cancers. The prevalence of streetlights, illuminated signage, and outdoor lighting in cities throughout the West often makes it harder for people to achieve restful, undisturbed sleep. This has broader implications for public health and well-being.
3. Loss of the Night Sky Beyond its ecological and health impacts, light pollution also diminishes the ability to enjoy the night sky. The bright glow from urban areas, known as skyglow, can wash out stars and planets, obscuring the view of celestial objects and diminishing the aesthetic and cultural value of the night sky. For amateur astronomers, as well as for communities that value stargazing as part of their heritage—as many rural communities do—this loss is both a scientific and cultural blow.
Five Principles for Dark Sky Compliant Lighting
The Illuminating Engineering Society and DarkSky International jointly have adopted 5 principles to control light pollution caused by outdoor lighting. The principles can be used to guide municipal planners in developing light pollution control standards.
Municipal Codes and Regulations
Municipalities are increasingly adopting building codes and lighting regulations to mitigate light pollution. Notably, the International Energy Conservation Code (IECC) requires new buildings and renovations to extinguish exterior lighting one hour after business hours, though the primary focus of this requirement is energy conservation. While light pollution reduction is an additional benefit, the IECC's lighting standards are part of a broader movement toward more sustainable building practices.
Local municipalities may adopt additional measures to specifically target light pollution, such as requiring lighting plans with permit applications, imposing light trespass restrictions, and enforcing glare limits. Another notable shift in lighting regulations includes a push for warmer light colors (under 3000K) to reduce the ecological and health impacts of high blue wavelength lights. In some regions, municipalities may also require the use of motion sensors, timers, and shielded fixtures to reduce unnecessary lighting and light spillage.
The guide Dark Sky Planning: An Introduction for Local Leaders has an excellent introduction to Outdoor Lighting Code and Lighting Zones, with links to other resources from the International Dark Sky Association, and other organizations. Additionally, there is a Dark Sky Lighting Ordinance Walkthrough available through the Colorado Plateau Dark Sky Cooperative, which highlights example ordinances from multiple rural communities in the Mountain West.
Case Studies: Western Success Stories
Several municipalities in the American West have already taken steps to curb light pollution through local ordinances. For example:
Flagstaff, Arizona is one of the most well-known cities to have enacted strict lighting regulations, earning the title of the world’s first Dark Sky City. These regulations include requirements for outdoor lighting to be fully shielded and a reduction of unnecessary nighttime illumination. As a result, Flagstaff has successfully preserved its dark skies, which is vital for both the local community and the nearby Lowell Observatory.
Boulder, Colorado has also made strides in reducing light pollution by incorporating sustainability goals into its lighting codes. Boulder’s ordinances require all new developments to submit lighting plans and use energy-efficient, low-Kelvin (warm) lighting, helping to preserve the quality of the night sky while promoting energy efficiency.
Helper, Utah, a small town in Carbon County, has made significant strides in dark sky preservation, earning membership in the International Dark Sky Association in 2020. The town adopted lighting ordinances to reduce light pollution, including shielded fixtures, energy-efficient LED streetlights, and regulations for new developments. Helper has leveraged its pristine night skies for dark sky tourism, and also emphasizes education, raising awareness about the environmental and health impacts of light pollution. As a historic coal and railroad community, Helper serves as a model for rural towns by thoughtfully enacting dark sky preservation efforts.
Sedona, Arizona, became one of the first cities to earn International Dark Sky Community status in 2001. Known for its stunning red rock landscapes, Sedona has implemented strict outdoor lighting regulations to protect its night skies. The city uses shielded lights and enforces lighting ordinances to minimize light pollution, balancing the needs of residents, businesses, and visitors. As a result, Sedona has not only preserved its natural beauty but has also created a thriving dark sky tourism sector, hosting events like the “Star Party” to educate the public about the importance of preserving the night sky.
Westcliffe and Silver Cliff, Colorado located in Colorado’s Wet Mountain Valley, received International Dark Sky Community designation in 2015. These small rural towns have worked together to pass comprehensive outdoor lighting ordinances aimed at preserving their dark skies. The communities have been proactive in educating residents and visitors about light pollution’s effects on both the environment and human health. Through events like the “Starry Night Festival,” they promote dark sky tourism, attracting visitors eager to experience one of the darkest skies in the United States. Their commitment to dark sky protection also supports local businesses and the region’s natural tourism appeal.
Jackson Hole, Wyoming situated near Grand Teton and Yellowstone National Parks, is committed to protecting its dark skies through the Jackson Hole Dark Sky Initiative. The community has implemented lighting ordinances that minimize light pollution in both the town and surrounding rural areas. Jackson Hole collaborates closely with national parks and nearby communities to create cohesive dark sky policies and reduce the impacts of artificial light on wildlife and natural ecosystems. The town promotes its dark sky status through public events and stargazing opportunities, positioning itself as a destination for eco-tourism and astronomical exploration.
These examples highlight the importance of strong municipal leadership and the positive impacts of proactive planning in reducing light pollution. Before-and-after data from such regions indicate measurable improvements in both the quality of life for residents and the protection of local wildlife.
The Role of Municipal Planners in Addressing Light Pollution
Municipal planners have a critical role in shaping the future of outdoor lighting by developing policies that reduce light pollution while ensuring safety and preserving aesthetics. Through careful planning and collaboration with stakeholders, planners can:
Educate the public and engage the community: Municipal planners can host public awareness campaigns and educational programs to inform residents and businesses about the impact of light pollution and the benefits of sustainable lighting. Public involvement can drive community-wide adoption of best practices and support for new regulations.
Promote sustainable lighting practices: Planners can encourage the use of energy-efficient technologies, such as LED lights with lower Kelvin ratings (preferably under 3000K), and implement smart lighting controls like motion sensors and timers.
Balancing Safety and Aesthetics: Municipal planners must balance safety with aesthetics when addressing light pollution. While adequate lighting is essential for public safety and visibility, designs should minimize glare, light trespass, and skyglow to preserve the beauty of the night sky. This approach ensures both safe environments and a peaceful atmosphere. Using modern technologies and scientific knowledge, planners can install lighting only where and when necessary, avoiding excessive illumination while maintaining safety. Leading by example helps spread these principles to the public, demonstrating that proper lighting, not total darkness, is the best solution.
Require detailed lighting plans: Requiring developers to submit lighting plans with permit applications, including details on light fixture location, lumen output, and color temperature, ensures that new developments comply with light pollution mitigation standards.
Collaboration and Best Practices: Municipalities can also work together and learn from one another's experiences to develop best practices for managing light pollution. Networking platforms, conferences, and workshops facilitate collaboration between planners and conservation organizations. These shared resources help create a framework for comprehensive policies that consider the diverse needs and unique characteristics of each community.
Conclusion
The adverse effects of light pollution are becoming increasingly clear, and municipal planners are at the forefront of efforts to reduce its impact on the American West’s ecosystems, human health, and the beauty of the night sky. By adopting sensible lighting regulations, encouraging the use of energy-efficient technologies, and fostering public engagement, planners can help preserve natural darkness and promote a healthier, more sustainable future for communities and wildlife alike.
Resources
DarkSky International - https://www.darksky.org
Colorado Plateau Dark Sky Cooperative - https://extension.usu.edu/iort/cp-darkskies/
Basin and Range Dark Sky Cooperative - https://brdarkskies.org/
Dark Sky Planning - An Introduction for Local Leaders - Aubrey Larsen, MsBRP
Dark Sky Assessment Guide - Evaluation Methods, Tools, & Resources - Aubrey Larsen, MsBRP
Lighting Code Basics - Aubrey Larsen, MsBRP
About the Author
Leo Smith is a seasoned lighting professional and environmental advocate with over two decades of leadership in the field of outdoor lighting and light pollution reduction. He has been a key figure in organizations such as the Illuminating Engineering Society (IES) and DarkSky International, where he contributed to the development of national lighting standards and policies. Smith has served on various IES committees, including the Roadway Lighting Committee, and chaired the IES special task force on when roadway lighting may not be necessary. As a former board member and Northeast Regional Director for DarkSky International, he helped shape the Model Lighting Ordinance and led initiatives to reduce light pollution's environmental impact. In 2024, he co-founded the Coalition to Reduce Light Pollution in Connecticut and developed a model for municipal outdoor lighting regulation. Smith's contributions have earned him numerous accolades, including the IES President’s Award and DarkSky’s Executive Director Award, and he continues to advocate for sustainable lighting solutions to address climate change.