Flip the switch to stop light pollution | Dr. Daniel Mendoza | TEDxSaltLakeCity

Key Concepts

• Light Pollution: Excessive and misdirected artificial light at night.
• Dark Skies: The absence of light pollution, allowing for clear views of the night sky.
• Light Trespass: Light falling where it is not intended or needed.
• Glare: Excessive brightness that causes visual discomfort and can impair vision.
• Punitive Lighting: Overlighting, often using flood lamps and spotlights, typically in lower-income or ethnically diverse neighborhoods, intended to deter crime but often ineffective and harmful.
• Shielding: Directing light downwards where it is needed, preventing upward light pollution.
• Color Temperature: The warmth or coolness of light, with warmer colors (lower Kelvin) being preferable for reducing blue light.
• Artificial Light at Night (ALAN): The presence of artificial light during natural darkness.
• Astro-tourism: Tourism focused on stargazing and experiencing dark skies.

The Impact of Light Pollution on the Night Sky and Ecosystems

The video highlights the significant issue of light pollution, noting that 80% of Americans can no longer see the Milky Way, and one-third of humanity is similarly affected. This pervasive issue extends beyond aesthetic loss, contributing to climate change by wasting energy and disrupting natural systems.

Environmental Consequences

• Migratory Species: Dark skies are crucial for many migratory species that rely on celestial navigation. Light pollution obstructs their view of constellations, stars, and planets, hindering their ability to find their way.
• Biodiversity Loss: Bird, mammal, and insect species essential to ecosystems face challenges due to light pollution. The monarch butterfly population, for instance, has declined by 90% since the 1980s, partly due to habitat loss and disrupted safe travel, impacting pollination of essential crops.
• Sea Turtle Disorientation: In Miami, newly hatched sea turtles are disoriented by city lights, turning them away from the ocean and towards danger.
• Fish and Amphibian Sensitivity: Efforts at the Desert National Wildlife Refuge aim to improve lighting conditions to protect fish and amphibians, which are more sensitive to light than humans.
• Plant Disruption: Continuous artificial light, including streetlights, prevents plants from resting, similar to humans and animals. A study found that trees exposed to artificial light develop tougher leaves, making them more resistant to insects, which disrupts the entire food chain.

Economic and Health Costs of Wasted Light

Light pollution represents a significant economic drain and has serious implications for human health.

Economic Waste

• Wasted Energy: Dark Sky International estimates that at least 30% of all outdoor lighting in the US is wasted, primarily due to unshielded lights.
• Financial Cost: The electricity used for this undirected and unshielded lighting costs over $3 billion annually, excluding the cost of damaged ecosystems.
• Offsetting Pollution: To compensate for the pollution generated by this wasted light, 875 million trees would need to be planted each year.

Health Impacts

• Sleep Disruption: Light trespass from streetlights, vehicles, or neighbor's displays can harm our ability to rest. Blackout curtains or eye masks can offer some relief for humans.
• Night Shift Workers: Night shift workers are particularly at risk due to constant exposure to artificial light, disrupting their natural sleep cycles. The Nurse's Health Study found associations between working second and third shifts and higher stress levels, increased blood pressure, obesity, and diabetes.
• Cancer Risks: A 2024 review of scientific literature found strong associations between artificial brighter environments and increased breast cancer rates (nearly 9% higher). A separate global study linked brighter aerial lighting to higher risks of lung, breast, and colorectal cancers.
• Vision Impairment: Glare from vehicles and streetlights can make roads more dangerous, especially for pedestrians and cyclists. Older drivers and individuals with early cataracts are particularly vulnerable. Glare at night or in tunnels is linked to a higher risk of accidents.

Misguided Lighting Practices and Solutions

The video critiques common lighting practices and proposes actionable solutions.

The Problem of Overlighting and Punitive Lighting

• Fear of Darkness: In Western cultures, darkness is often associated with evil and danger, leading to the adoption of overlighting and inappropriate lighting to create a perceived sense of safety.
• Increased Risk: Ironically, overlighting can actually increase risk by creating unsafe spaces due to the time it takes for vision to adjust to brightness fluctuations.
• Disproportionate Application: Punitive lighting, including excessive use of flood lamps and spotlights, is often implemented in lower-income, higher ethnic diversity neighborhoods, ostensibly to reduce crime.
• Ineffectiveness: Communities employing punitive lighting have not seen a reduction in crime; in many cases, crime has remained the same or even increased.

Effective Lighting Strategies

• Targeted and Timed Lighting: Light should only be used where and when it is needed.
• Proper Shielding: Shielding lights directs them downwards, improving visibility while reducing trespass and glare.
• Warmer Color Temperature: Using warmer colored lights provides clarity and reduces blue light, which strains eyes, disrupts sleep, and can negatively impact long-term health.
• Dimming Lights: The example of Tucson, Arizona, demonstrates the effectiveness of dimming streetlights. Nearly all streetlights are set to 90% brightness, dimmed to 60% at midnight. A study showed that dimming to 30% at midnight was nearly imperceptible to residents, resulting in considerable energy savings without complaints. The argument is made that if all lights could be dimmed slightly, it would reduce energy costs, increase safety, and cut light pollution.

Preserving Dark Skies for the Future

The video emphasizes the urgency of protecting dark skies and highlights successful preservation efforts.

The Loss of Celestial Observation

• Astronomical Research: Astronomers rely on clear night skies to study the universe's past.
• Cultural Traditions: Many cultures depend on constellations for sacred ceremonies.
• Satellite Interference: Satellite trains, moving in groups, have become so bright and frequent that they are disrupting astronomical observations and potentially impacting cultural practices.

Solutions and Opportunities

• Dark Sky Certification: Unlike air and water pollution, dark sky solutions are readily available. Utah is presented as a leader, with more dark sky certified places than anywhere else on Earth, including all five national parks, six national monuments, and nine state parks.
• Astro-tourism: This is a growing industry, with communities like Helper, Utah, actively sharing their dark skies with visitors.
• Individual Action: "Flip the switch" – turning off unnecessary lights – is presented as a simple action with a significant positive impact on nature.

Conclusion

The video concludes by reiterating that light at night is not harmless and has far-reaching consequences for ecosystems, economies, and human health. The call to action is to reduce light pollution by using light only where and when needed, employing proper shielding and warmer color temperatures, and dimming lights when possible. As author Craig Childs is quoted, "a night sky is not an absence of light. It is the presence of the universe." The message is to "Turn down the lights, look up, and let the universe shine through."