I admit that I don't like light pollution because it spoils the beauty of the nighttime sky. It obscures the majestic swath of stars across the sky that make up our Milky Way Galaxy (yes, this is what our naked eyes would see without light pollution - but a tad dimmer) and washes out the delicate structure of galaxies and nebula as seen through the telescope. Because of light pollution, many people are unaware that the Andromeda galaxy appears larger than the moon in our skies and can be seen with the naked eye.
The most useful lighting radiates downward illuminating our yards, roads, and parking lots. However, lighting that is poorly designed can radiate in all directions, thus wasting that 50% of the light that goes up into the sky and pollutes our view.
There are several negative consequences. Most obviously, energy is wasted. With simple reflectors that direct lighting downward, half the wattage is required to get the same amount of useful illumination.
Bright street lights that are not aimed downward can temporarily impair a driver's vision. Our campus at Washington State University has lighting in several places near crosswalks that is blinding to drivers and obscures pedestrians. I once almost hit a pedestrian at such a crosswalk.
As we age, our pupils respond more slowly under changes in lighting; so, older drivers that leave brightly-lit shopping centers have trouble adjusting to lower light levels as they leave the parking lot. Several accidents have been attributed to this effect.
Contrary to the claim of business owners that bright lights attract customers, studies show that glaring lights are less inviting and result in fewer customers. Many municipalities believe that bright lights reduce crime; but, cities that have reduced lighting levels have found crime rates to either stay the same or decrease. Ironically, the lighting at our local Walmart is of the full cutoff type, which sends the least amount of lighting upward.
Bright night lighting has other negative impacts on the environment. City lights are known to disorient migrating birds and have been found to be responsible for the demise of whole flocks of confused animals that flew into structures such as buildings.
Night lighting is also known to adversely affect our circadian rhythm, which requires periods of dark. The biological effects of bright nighttime lighting has also been associated with increased incidence of certain types of cancer.
Turns out that there is one other reason for eliminating light pollution. A form of nitrogen oxide in our atmosphere breaks down chemicals from vehicle exhaust and other man-made sources. However, this compound is destroyed by the sun, so this natural cleaner works only at night. Researchers at NOAA and CIRES found that light pollution also destroys the nitrate compound, so its cleansing effect is lost.
Let's fight light pollution so that we can save energy, decrease greenhouse gasses, protect wildlife, improve our health, and allow nature to clean the pollution that we create. All it takes is light fixtures that direct lighting downward. The icing on the cake is that decreased light pollution will allow us to once again stare in awe at the beauty of our universe, allowing photons that originated millions of light years away in other galaxies to directly tickle our optic nerves.