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The term "Light pollution" is a broad one that is associated with three major areas of concern. These three areas are:
The vast majority of people today don't consider lights to be type of pollution, this is likely due to the fact that there are so many other environmental groups in the world that all focus on different aspects of 'pollution' eg., water, air, sound, etc. If one looks at the causes, a relationship can be seen to link light as yet another source of pollution.
One example of the ability of light to pollute is commonly seen in your typical street lighting. The most frequently used type of fixture is commonly called the "Cobra Head" named for it's resembalance to the snake which when provoked expands the size of its head to intimidate. The "Cobra-head" light fixture consists of a large metal head, with the lens mounted below. The bulb is easily accessible by swinging this lens downward. Unfortunately this also allows the bulb to easily be seen, and the light from it is not focused downward onto the street but is allowed to escape horizontally as well. Depending on what is below the "Cobra-head" fixture this drop-down lens also allows light to readily be reflected above the horizontal enough that people flying above a city can easily see the lines of streetlights.
Another example is an unshielded security light can create so much glare that our irises close up, making it impossible to see a criminal lurking in the shadows right beside us! Our peripheral vision has evolved to work at its best at low light levels. A yard flooded with light all night long wastes energy, costs money, and pollutes the environment. Improperly directed lighting causes glare which can be hazardous to drivers, cyclists and pedestrians.
When the light isn't being focused where it is most useful, and when it is being allowed to spill outwards and upwards we have wastage of both the amount of light required to illuminate a given place, as well as the amount of power required to generate this light. In other words if a given city, town, business is paying to illuminate a road, or parking lot etc. why is so much light being directed where is isn't needed. If for the moment we ignore the pollution aspects of these lights the amount of power being used by them is astounding. The International Dark Sky Association estimated a few years ago that upwards of thirty percent of roadway lighting never reaches its target. So for example if a given light fixture costs $1000 dollars a year to run, then $300 of that is lost, when this is multiplied by the number of light fixtures in a typical city, that adds up to a lot of money. In the United States this would translate to a loss of $1.4 Billion annually. And you know where the money is coming from right - your taxes! At present I don't have figures for Canada, but they will hopefully be posted in the near future.
To help stop this loss of power, and light a number of municipalities in the United States, and some in Canada are in the process of converting to a different type of bulb known as "Low Pressure Sodium", in addition when these bulbs are housed in "Full Cut-off" fixtures the results are astounding. One example of this is the City of San Diego, which by converting all its street lighting to Low Pressure Sodium was able to pay for the conversion program in three years, and since then has been saving millions of dollars. Another example are our neighbours to the South - Calgary who are well on their way to reducing their light pollution and expenses by significant amounts.
Now granted replacing all the fixtures at one time is a fairly drastic program, but there are other solutions. One is current fixtures could be retro-fitted with reflectors / shields that would direct the light beam downwards. Another solution would be to gradually replace them with full cutoff, low pressure sodium fixtures as the existing light reaches its scheduled replacement date. These fixtures are slightly more expensive to purchase, but pay for themselves within a few years of use by being less expensive to maintain, with additional savings for the remaining lifetime of the fixtures.
With all the other types of pollution in the world it does seem rather trivial for us to be talking about lights. However for every hour a given light is on additional greenhouse gasses, in addition to the by-products of the power generation process are being released into the earth's atmosphere. Canada committed itself to the Kyoto Accord and promised to reduce its greenhouse gas production below 1990 levels by 2010. and to further reduce them by five percent by 2015. If we were to convert from current street lighting fixture to energy-efficient low pressure sodium one this would put us well on our way to fullfilling this committment.
A number of years ago various power companies predicted the the demand of power would soon outpace the ability of companies to supply it. This would result in brown-outs. With the reliance of businesses on a constant source of power for their computer systems, etc. this could be disastrous. If we were to phase in energy saving lighting such as low pressure sodium, situations such as this could easily be averted, and it is also much cheaper than building new power plants.
If we now switch our focus to driving conditions imposed on drivers by these same cobra-head lights we face a different problem. Unshielded street lights produce significant amounts of glare for oncoming traffic, which can make it extremely difficult to see pedestrians, cyclists, traffic lights, etc. Large amounts of glare have also been shown to cause driver fatigue, and this leads to accidents etc. Properly shielded lights make driving more enjoyable, and much safer.
With their proper shielding, all the light that is generated goes onto the road, creating less glare, and using the light more effectively. Some of these lights are already in use in Edmonton at the north end of Anthony Henday drive. If these these lights were used to replace existing lights as the current ones fail, and in all new residential installations, the City could ultimately save a substantial amount of money, reducing our tax burden.
As Edmontonians pride ourselves on our respect for the environment. Our river valley is the crown jewel of the capital region. We are consistently winning awards for our leadership in recycling, and other environmental activities. Yet our beautiful night sky, taken for granted by our grandparents, is now almost gone. In its place are crisscrossing spotlights and the orange glow from poorly designed street lighting. Someday, we could even see corporate logos being projected onto the clouds above. Businesses aren't allowed to chop down river valley trees to install billboards, so why are they allowed to blot out the stars with spotlights and glare?
There are numerous other reasons to promote proper lighting. As a member of the Royal Astronomical Society of Canada one of the benefits that comes to mind immediately is the effect a sky filled with stars has on the public. When I was young back in the sixties we could easily see thousands of stars from our backyard (and I lived on St. Albert Trail, which back then was a major thoroughfare). Today people are lucky on a clear night in the city to see maybe a hundred. If we encourage the youth of today to give up the video game controls for a while and enjoy nature they can learn a great deal about the world. Astronomy for instance is part of the grade five & six curriculum in Alberta schools, as well as other grades. An understanding of astronomy can also lead to interest in physics, mathematics, space flight, and a general interest in science. On Hallowe'en night in 2002 I set up a telescope in my front yard - unfortunately between two street lights, and attracted a crowd of over fifty people throughout the night (the previous year I had no telescope, and less than twenty visitors). My only stipulation was that if the children wanted a candy, they had to look through the scope. Due to the poor lighting I was forced to focus primarily on a few of the brighter stars, but the people who came were fascinated. A number also came back a few hours later when Saturn became visible. Now if the lighting was at decent levels the viewing would have been spectacular as Uranus, and Neptune were also visible earlier on, as various nebula and galaxies would also have been visible. Maybe next year!
As you can see there are numerous things that can be done to combat light pollution including properly focused lighting, shielding, phasing in low pressure sodium & full-cutoff fixtures. It is true that some of these are expensive, but the saving to the various municipalities in the long run would be beneficial.
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