Light pollution arises from careless and often misguided exterior night lighting practices. Light pollution wastes energy, causes hazardous glare, increases the production of greenhouse gases, and compromises public safety.
What is Light Pollution?
Air pollution in the form of smog and haze can significantly reduce the number of stars which are visible to the naked eye, even on a dark moonless night. However, light pollution is just as bad (or in some cases worse) than other forms of pollution.
As the diagram above shows, light pollution blots out the stars. However, the effect can be reduced by simply using properly shielded outdoor lighting fixtures.
Myth 1: The brighter the better. WRONG!
The human eye responds differently to low levels of illumination than to high levels of illumination. When levels of illumination are low, the human eye adapts and becomes much more sensitive to the available light.
Ever wonder why your bedroom seems so dark when you first turn off the lights and then, after about 20 minutes or so, the room seems much brighter? This is called “dark adaption” or “night vision”.
Constant and uniform levels of nighttime lighting at a moderately low level provide the best all-round visibility of your surroundings.
Light which can be seen coming directly from exposed lamps destroys night vision, causes “blinding” glare, and wastes energy, allowing light to reach the sky instead of the ground.
Myth 2: Bright lights enhance public safety. WRONG!
Unshielded bright lights create extreme levels of contrast by producing areas of dark shadows adjacent to areas of intense glare.
Studies have shown that brightly illuminated areas having a dark perimeter (the area you see with your back to the light) are less safe than the same area having no artificial light source whatsoever!
Both glare and deep shadow obscure your vision – a very unsafe situation.
Myth 3: All lights are the same. WRONG!
Outdoor lamps which allow light to shine above the horizon are wasteful of energy, and since they use electricity, they indirectly contribute to the production of greenhouse gases, notably carbon dioxide.
Unshielded lights produce glare that contributes to “light-trespass” (the shining of unwanted light onto neighbouring properties) and cause poor visual adaptation.
Properly shielded lights can use less wattage to attain the same ground level illumination, thereby saving energy costs. Using less energy also means producing lower levels of greenhouse gases from fossil fueled electrical power generation stations.
Myth 4: Cheap lights save money. WRONG!
Well shielded lights, which reflect all light to the ground and cut-off horizontal glare, require lower wattage bulbs to achieve the same level of ground illumination as lights which allow extraneous light to escape into the sky.
In the long run, the extra money invested in well designed lighting fixtures more than pays back the investment, because of much lower long-term energy costs.
Myth 5: Nobody really cares about the night sky. WRONG!
Highly illuminated urban areas are known to confuse transient migrating birds and to upset the natural survival rhythms of many nocturnal animals.
Light pollution also causes stars to be “lost” in the bright background, effectively destroying our ability to see the natural beauty of the night sky.”
The Canadian Space agency did a marvelous job on outlining the dangers of light pollution. Well done!
Let there be night!