Light Pollution is a man-made phenomenon starting with the light bulb in 1900’s being used outdoors for backyard flood lights, street lights, Parking lots, businesses and stadiums. The International DarkSky Association (IDA) was founded in Tucson in 1988 by two astronomers to bring attention to this issue through Education and to help find solutions to mitigate this problem.
WITH Outdoor Lighting Codes 
WITHOUT Outdoor lighting Codes
How Much Light Pollution Do You Have In The Area Where You Live? (see map)
Click on the “see map” link above then pan and zoom in/out for any part of the world. The map legend shows two sets of readings. The dots are the colors with corresponding ranges, same values when measuring sky brightness using the handheld Sky Quality Meter (SQM).
Our parent IDA organization has done a fantastic job describing Light Pollution and developing Brochures. Check it out!