Bronte Wells
Street lights are a significant contributor to light pollution, which is the human-made alteration of outdoor light levels from those occurring naturally. Light pollution has harmful effects on human health, wildlife behaviour, and the environment. It is caused by the excessive or inappropriate use of outdoor artificial light, which is often the result of poor lighting design. Street lights, in particular, contribute to light pollution when they are not properly shielded or cut off, allowing light to escape above the horizontal and brighten the night sky. This phenomenon, known as sky glow, is not limited to street lights and includes light from billboards, signs, and illuminated facades. To reduce light pollution, it is essential to implement well-designed lighting that minimizes glare, dims lights when possible, and turns off lights when they are not needed.
| Characteristics | Values |
|---|---|
| Street lights are a source of light pollution | Street lights are a source of light pollution, but they are not the only one. Common sources also include parking lot lights, exterior lights, and illuminated signs. |
| Light pollution is caused by bad lighting design | Light pollution is caused by lighting design that allows artificial light to shine outward and upward into the sky, rather than focusing it downward where it is needed. |
| Impact of light pollution | Light pollution has harmful effects on human health, wildlife behaviour, and the environment. It disrupts natural day and night cycles, suppresses melatonin production, and increases energy consumption and costs. |
| Reducing light pollution | Light pollution can be reduced by improving lighting design, using shielded or cut-off light fixtures, and dimming or turning off lights when not in use. |
What You'll Learn
Poor street light design
Street lights are a crucial source of light in cities, but they are not always well-designed or maintained. One common issue is the lack of shielding or cut-off on light fixtures, allowing light to escape above the horizontal and brighten the night sky, known as "sky glow". This not only reduces our ability to see the stars but also has negative consequences for human health and the environment. Excessive light at night disrupts our natural circadian rhythms, which are essential for our biological welfare.
To reduce light pollution, street lights should be designed to direct light downwards, focusing on the area that needs illumination. This can be achieved through the use of shielded light fixtures, tilting angles, and intelligent control systems. For example, the city of Tucson, Arizona, combined LED street lights with a "smart city" lighting control system, allowing them to monitor and dim the lights as needed.
In addition to better design, proper installation and maintenance of street lights are crucial. The installation angle, spectrum selection, lighting distribution, and use of lamp LEDs all play a role in reducing light pollution. By considering these factors, cities can ensure that street lights meet lighting requirements while minimizing their impact on the night sky.
Furthermore, reducing light pollution is not just about street lights. It's about auditing the priorities of a city and considering other sources of nighttime lighting, such as commercial lighting, parking lot lights, and advertising signs. By working together, activists, pedestrians, and policymakers can implement solutions that balance safety and lighting while reducing light pollution.
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Inefficient light fixtures
Light pollution is caused by the inefficient or unnecessary use of artificial light. Common sources of light pollution include street lamps, parking lot/shopping mall lights, exterior lights found on most homes/businesses, neon signs, and illuminated signboards.
To reduce light pollution, it is recommended to use full cutoff lighting fixtures, which prevent light from escaping above the horizontal plane. However, these fixtures have been criticised for being less aesthetically pleasing and requiring expertise to install effectively. Flat-lens cobra luminaires, which are full-cutoff fixtures, are effective in reducing light pollution by directing light only below the horizontal.
In addition to improving fixture design, it is important to adjust the type of lights used. Mercury, metal halide, and first-generation blue-light LED road luminaires are more polluting than sodium lamps. The use of dimmable streetlights and control systems can also help reduce light pollution, as demonstrated in Tucson, Arizona, where streetlights were dimmed to 60% intensity after midnight, resulting in energy savings and reduced light pollution.
By addressing inefficient light fixtures and making thoughtful choices about lighting design and technology, we can reduce light pollution and its negative impacts on the environment, human health, and wildlife.
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Lack of light control systems
Street lights are a significant contributor to light pollution, but they are not the only culprit. Light pollution is caused by the excessive or inappropriate use of outdoor artificial light, and it can have negative impacts on human health, wildlife behaviour, and the natural environment. The light from street lamps and other sources shines outward and upward into the sky, where it is not wanted, instead of being focused downward. This results in the brightening of the night sky, known as sky glow.
One way to reduce light pollution is to implement light control systems. These systems allow for the adjustment of public lighting in streets, squares, sidewalks, residential areas, and vehicle roads. However, some cities have struggled with their light control systems, as the lights may not dim as programmed or they may return false data. Standardization and the addition of tools are needed to help cities operate their light control systems effectively.
One example of a city that has successfully implemented a light control system is Tucson, Arizona. In 2017, the city converted more than 19,000 municipal street lights to LED and combined them with a "smart city" lighting control system. This system allows each light to be monitored and dimmed individually. By dimming the lights, Tucson was able to make the sky after midnight darker, reducing light pollution.
Another way to reduce light pollution is to shield lights to reduce glare. Glare can cause safety-related dangers by reducing visibility. Dimming lights and turning them off when they are not needed can also help to reduce light pollution.
In addition to improving light control systems, it is important to address other sources of light pollution, such as billboards, tall buildings, large-scale signs, sports stadiums, and parking lots. Reducing light pollution requires a comprehensive approach that considers all sources of artificial light and their impact on the environment and human health.
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Excessive light
The ever-expanding reliance on outdoor electrical lights is a global issue. Artificial light from towns and cities increases annually, with more than 99% of the US population living under light-polluted skies. The Milky Way is hidden from nearly 80% of North Americans. This has a profound impact on our biological welfare, as darkness is essential to our circadian rhythms, a biological imperative that has been disrupted by the presence of light at night.
The economic effects of light pollution are also significant. The International Dark-Sky Association estimates that one-third of all lighting is wasted, costing $2.2 billion annually. This wasted light also contributes to energy wastage and greenhouse gas emissions.
To reduce excessive light, it is important to consider the design of lighting systems and the direction of light. Light fixtures should be fully shielded or cut off to prevent light from escaping above the horizontal and spreading into the sky. This can be achieved by using solutions such as glass or sunshades for lamps to reduce upward or backward emissions. Additionally, intelligent control systems can be used to monitor and dim lights when necessary.
By implementing these measures and working together with initiatives like the Dark Sky movement, it is possible to reduce excessive light and light pollution while still maintaining functional and safe lighting in our cities.
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Light trespass
Street lights are a significant contributor to light trespass. In many cases, street lights are poorly designed or installed incorrectly, resulting in light shining into nearby homes or properties. This unwanted light can disturb residents, causing sleep disruption and impacting their quality of life.
To address light trespass, several measures can be implemented:
- Shielding: Adding shields to street lights can help direct the light downward, preventing it from spilling into unwanted areas. Shields can be installed by the local utility company or the manufacturer of the streetlights.
- Dimming: Reducing the intensity of street lights through dimming can decrease the amount of light trespass while still providing adequate illumination for safety.
- Adjusting light positioning: Changing the angle or height of street lights can help direct light to the intended areas and reduce spillage into neighbouring properties.
- Using optical options: There are various optical tools and techniques that can be employed to better control the direction of light, such as using lenses or reflectors.
- Replacing lights: In some cases, replacing the light fixture with a less intense light source may be necessary to reduce the impact of light trespass.
It is important to consult local regulations and work with lighting specialists to ensure compliance and effective light trespass mitigation. Additionally, advocating for well-designed street lights and collaborating with local governments and politicians can help address light trespass issues and promote responsible lighting practices.
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Frequently asked questions
Light pollution is the human-made alteration of outdoor light levels from those occurring naturally. It is caused by the excessive or inappropriate use of outdoor artificial light.
Street lights are a major source of light pollution, but they are not the only culprits. Poor street light design allows artificial light to shine outward and upward into the sky, brightening the night sky and causing sky glow. This is detrimental to human health, wildlife behaviour, and the environment.
Light pollution has harmful effects on human health, wildlife behaviour, and the environment. It can interrupt sleep and confuse the internal, twenty-four-hour clock that guides day and night activities, affecting physiological processes in nearly all living beings. It also contributes to energy wastage and the emission of greenhouse gases.
To reduce light pollution caused by street lights, we can implement better street light design and installation practices. This includes using shielded or dimmable lights, adjusting colour temperatures, and concentrating light beams on useful areas that need illumination. Additionally, we can limit unnecessary sources of nighttime lighting, such as advertising signs and commercial lighting.
