Introduced light can also cause developmental irregularities, such as retinal damage, reduced juvenile growth, premature metamorphosis,  reduced sperm production, and genetic mutation.
No filter can match the effectiveness of a dark sky for visual or photographic purposes. Now, artificial lights overpower the darkness and our cities glow at night, disrupting the natural day-night pattern and shifting the delicate balance of our environment.
The results showed a statistically significant correlation between outdoor artificial light at night and breast cancer, even when controlling for population density, affluence, and air pollution.
But it is not just sunlight that can break down NO3; any light can do this, especially those city lights that are left on all night long. Melatonin is potent anti-oxidant, anti-carcinogen, and is responsible for regulating metabolism, and immune responses.
LPR filters work by blocking light of certain wavelengths, which alters the color of the object, often creating a pronounced green cast. A lamp's light output rating expresses the total amount of light emitted in all directions per unit time. Full cutoff typically reduces the visibility of the lamp and reflector within a luminaire, so the effects of glare are also reduced.
The effectiveness of using full cutoff roadway lights to combat light pollution has also been called into question. Unfortunately, it is far, far easier to setup a badly installed light outside than it is to understand the negative effects it casts down-light from it.
For the same melatonin suppression problems we have with lights at night, creates similar problems in animals. Furthermore, LPR filters only work on certain object types mainly emission nebulae and are of little use on galaxies and stars.
Artificial light has benefited society by, for instance, extending the length of the productive day, offering more time not just for working but also for recreational activities that require light.
The same legislation also imposes a minimum distance between street lamps of about four times their height, so full cut off street lamps are the best solution to reduce both light pollution and electrical power usage.
Melatonin is a hormone that regulates photoperiodic physiology and behaviour. So no living species ever evolved to take advantage of continuous lighting. All text from EHP may be reprinted freely. In fact, it is found in almost all organisms.
Sea turtles provide one dramatic example of how artificial light on beaches can disrupt behavior. It dealt with bats, turtles, the "hidden" harms of LAN, and many other topics. They also maintain a blog on light pollution and related issues. Light pollution can come in several forms: light trespass is when unwanted light escapes from one property into adjacent properties; over-illumination is using excessive light where it isn't needed; light clutter is the redundant clusters of lighting found in many urban centers; sky glow is the collective light pollution found over big cities.
Light in the wrong place at the wrong time can be intrusive. There has been an increase in complaints about light to local authorities in recent years.
This brochure looks at the different aspects of light pollution, explains the steps that can be taken to reduce it and describes what you can do if faced with the problem of pollution from light.
Light pollution is a side effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, commercial properties, offices, factories, streetlights, and illuminated sporting venues.
Light pollution is excessive and inappropriate artificial light. The four components of light pollution are often combined and may overlap: Urban Sky Glow—the brightening of the night sky over inhabited areas. Light Trespass—light falling where it is not intended, wanted, or needed.
“The policy implications of unnecessary light at night are enormous,” says Stevens in reference to the health and energy ramifications [for more on the energy impact of light pollution, see “Switch On the Night: Policies for Smarter Lighting,” p.
This map is based on light pollution data updated in by David Lorenz. Attribution for original data: P. Cinzano, F. Falchi (University of Padova), C. D. .Light pollution