Paul M. Sutter for Universe Today:
For years we’ve assumed that streetlights are the main culprit behind light pollution, but a recent study has shown that streetlights contribute no more than 20% of all the pollution, and if we want to solve this vexing astronomical problem, we have to think harder.
Tuscon, Arizona did a research study on how much light pollution their street lights produced. It turns out to only be a small part of the problem. As Sutter points out, we have to do more. I refer you to my post about how we can help.