Even though light pollution is a serious and growing global concern, it's one of the easiest environmental problems that can be addressed on local levels.
GLOBE at Night is an annual two-week campaign in March. People all over the world record the brightness of their night sky by matching its appearance toward the constellation Orion with star maps of progressively fainter stars. They submit their measurements on-line and a few weeks later, organizers release a map of light-pollution levels worldwide. Over the last four GLOBE at Night campaigns, volunteers from over 100 nations have contributed 35,000 measurements.
Audio podcast on light pollution and how to participate in GLOBE at Night
A Powerpoint (with audio and written transcripts) on light pollution and how to participate in GLOBE at Night