Key Light-Pollution Issues

In a nutshell, there are three basic problems with outdoor night lighting:

• A majority of outdoor lights are simply too bright (unnecessarily bright).
• A majority of outdoor lights are not properly shielded, and thus cause unwanted and unsafe and expensive light trespass and glare.
• There are simply too many unnecessary outdoor lights out there (a great many paid for by you, the taxpayer). Very few highways or streets need to be lit with expensive streetlights (intersections and walkway crossings are the important places to have good lighting); it is far better to have bright, clear painted roadway lines and good, clear signage. Divided highways should have high barriers and/or planted trees/shrubs to block oncoming headlights. But roadside business and residential lighting also needs to be shielded (and low-intensity lights employed) so as to promote the safety of motorists from potentially fatal glare. And most parking-lot lights can and should be turned off "after hours".

The key problems that need addressing by politicians and governments, by power utility companies, and by any homeowner or business owner who lights their property at night, are as follows:

• We tend to light areas at night with fixtures that spread light where it is not needed (outwards and upwards). This is a significant safety hazard to motorists, pedestrians, and bicyclists at night, and is very thoughtless of senior citizens who have more difficulty with scattered light at night. It also wastes as much as US$2 billion of energy per year in the USA alone, in terms of light energy going skyward, with perhaps 2.5 percent of all electricity used for outdoor night lighting (cf. Hunter and Crawford 1991, Astron. Soc. Pacific Conf. Ser. 17, 89). The simple solution is to use fully-shielded (full-cutoff) outdoor lighting, which points the light down and not out and upward.

• Unshielded lights represent a colossal waste of energy and money, and they are a hugh blemish on the record of 20th-century society and technology; their glare is dangerous to motorists (and plain ugly and intrusive to homeowners, night-sky viewers, and others), and they should be banned from any taxpayer-funded usage! Brighter, more-expensive higher-wattage lamps are needed in unshielded fixtures because so much light is wasted. Full-cutoff fixtures place all of the light onto the ground below, where it is useful and needed, and for this reason lower-wattage (lower-lumen) bulbs can be used, and great taxpayer savings (or great business/residential savings) thereby realized. (Note that some lighting engineers are contesting this remark, saying that not enough light is reaching the ground with full-cutoff fixtures if lamp wattages are lowered, and there is the problem that there are not yet enough gradation differences in lumen outputs among sodium and metal-halide lamps --- meaning that such lamps need to be produced in 10-lumen increments, rather than the 50-or-more-lumen increments that tend to be the case now. But the fact remains that a good percentage of light in unshielded or partly shield outdoor lamps goes outward and upward in a totally useless manner, and proper reflectors in full-cutoff fixtures should allow substantial reduction in the lumen outputs of the lamps -- common sense indicating huge potential energy and money savings to go along with glare reduction or elimination!)

• Shielding lights with a full-cutoff lens that directs the light properly and uniformly onto the ground can produce huge savings now by utilizing low- and high-pressure-sodium (LPS and HPS) and metal-halide lamps with wattages of 50 or less even for most streetlights (a 50-watt HPS or MH lamp is very bright!). There is a movement nowadays away from the older mercury and incandescent outdoor lamps to metal-halide, HPS, and LPS -- and sometimes even fluorescent -- lamps, these newer lamps being all much more energy efficient than the older mercury and incandescent lights. The problem is that utility companies want to keep their income at the same level, so unless told otherwise, they will install (for example) an HPS lamp of the same wattage as the older mercury or incandescent lights, creating 2-4 (or more) times as much light! In general, taking out a 150-watt mercury lamp and replacing it with a 35-watt LPS or 50-watt HPS lamp will give the same amount of light, and cut the cost of lighting substantially.

• People are generally unaware of how expensive it is for a town or city to light its streets. They are also unaware that cities and towns are not obligated by law to put any lights out at all! Outdoor lighting is optional, but cities and towns are usually run over by power-utility companies who want to make money off of the taxpayers. A typical town in eastern Massachusetts with a population of 25,000-30,000 will have perhaps 3,500 street lights that its taxpayers will spend as much as $500,000 per year to keep lit all night long. Many towns are electing to turn off street lights to help budgets these days, usually finding that turning off lights does not increase either crime or traffic-accident rates (in fact, both rates sometimes decrease when glary lights are turned off)! See NELPAG Circulars and IDA literature for supporting documentation; a more recent example is Concord, MA, which has removed (or is removing) 200 streetlights to save money in the town budget (Boston Globe, 2003 Nov. 27).

• Power-utility companies propagate a myth that most people want more outdoor night lighting. In fact, thirty years ago most people thought that outdoor streetlighting levels (which were then a tiny fraction what they are today) were fine. And, in towns and cities today where lights are turned off to save money (or the streetlights made less "visible" via the introduction of full-cutoff fixtures), a minority of people have an initial misconception that not enough light is on hand, but after a few months people cease finding fault or problems with reduced lighting and/or reduced glare. The reason, of course, is that our cities and towns are so grossly over-lit at night that a large reduction in both glare and actual lighting will still leave plentiful levels of lighting. And many power-utility companies will try to say that they "can't" install full-cutoff lights, for one or another lame reason; they seem unaware of the fact that large population centers and key states have full-cutoff official policies now (from the city of Los Angeles to the state of Texas to the Illinois Dept. of Transportation). The problem is that many such power-utility officials are not well educated on outdoor lighting, and this is where the public must help them do their jobs properly.

New England Light Pollution Advisory Group (NELPAG)