What is light pollution?
Before the 19th century, people used the moon, torches and oil lanterns to light their way at night. Our night vision was dramatically changed with the invention of electricity and so was our night sky. Light pollution can be defined as any modification to the natural light environment. The most common forms of light pollution are sky glow, light trespass and glare.
Light pollution and star gazing:
Our ancestors used the stars to navigate by, they documented the night sky to create calendars, they used the cycle of the stars to tell them when to plant crops; the night sky was an integral part of their lives. Today only about 3% of the stars are seen from most cities and suburbs and we need to travel far from the city lights (pollution) to see a clear starry night. If you live in a rural environment you are probably lucky enough to still see the stars…but light pollution is encroaching into those areas too.
Why is this important?
One of the most obvious consequences of light pollution is the work of astronomers, a dark sky is essential to astrophysicists for the observation of celestial objects. And of course, we all know about the hatching turtles and their disorientation in heading for the city lights instead of the reflection of the stars on the ocean.
Outside of the obvious, there are many studies now being done on the effect of too much night light on our bodies. Studies are showing that not enough dark time can affect our sleep and our health by changing the natural levels of melatonin in our systems. This could be contributing to our inability to fight disease and cancer.
Up until about 120 years ago we rose with the sun and slept with the moon. Our bodies were used to about 12 hours of daylight and 12 hours of dark (annual average). Today we are averaging about 18 hours of light and 6 hours of semi-dark. At bedtime tonight take a look around your house, is really dark? Or is there light coming in the room? Perhaps from a street lamp, the head lights of cars going by, the glow of your alarm clock?
Why do we require more light at night?
Quite simply – safety. We want to feel safe in our environments. Since the beginning of time humans have been afraid of the dark, of what we don’t know, of what we can’t see. Artificial light has given us security and control.
What can we do?
There are many things that each of us can do. No, we can’t control the street lights, the cars or the beacons of the high rise buildings. We can however improve the quality of light in our spaces. If every homeowner made a few simple changes, we would greatly reduce the affects of light pollution. Here are a few practical tips to help you get started.
Access your requirements:
Is lighting really needed?
Good quality lighting can add value to your property, increase safety and create a welcoming atmosphere.
What areas or objects need to be lit?
Lighting stairs and pathways is important for security and safety. Especially important if the path is hard to navigate or has obstacles in the way. People feel safe and comfortable when they can see the area around them.
How much light is needed?
Direct the light where it is needed. Casting light up into the sky or light trespassing into adjacent areas is a waste of energy. Avoid glare. A luminaire that emits a concentrated beam of light offers better visibility than one that shines light in all directions. Sometimes glare can compromise the safety we are trying to achieve. Consider the ambient light in the area. Is your neighbor’s light adequately lighting the side of your house too?
When is the lighting necessary?
Assess the times light is required and control the lights. If switched from indoors, add a dimmer, this will save you money by using less electricity and will increase the life of your light bulbs. Add photocells, motion sensors or a time clock so you can have control over the hours of operation.
Choose the right fixture for the task:
- Avoid lighting up the sky; remember that light directed towards the sky does not improve night vision.
- Excessive illuminance constitutes light pollution and is a waste of energy. It is best to produce a moderate yet uniform illuminance. As an example; a full moon provides very low but uniform illumination without glare.
- Choose luminaries that do not emit light above the horizon line. Fixtures with flat lenses or have a shield over the upper portions of the bulb (the bulb is regressed in the fixture) are classified as “cut-off” luminaires and are approved for dark sky.
- Install fixtures under an eave or balcony so the light can’t escape into the sky.
- Aim the fixture where the light is most needed.
Without compromising our safety and well being, a few simple changes in way we light our outdoor spaces can help bring the stars back to our night skies.