I leap to follow up on Jackie's suggestion.
The quotation is from a motto : "Only you can prevent forest fires."
Many years ago, LIFE magazine's last page always had The Picture Of The Week and one week it was a photo of a singed baby bear cub that had been rescued from a forest fire in New Mexico. He was named Smokey. The photo caused quite a national stir and the little bear became famous and was adopted as a mascot by the Fire Service. Since most forest fires are started by careless disposal of matches or by campfires that are not put out properly the slogan was adopted and "spoken" by Smokey. The real Smokey was at the National Zoo in Washington D.C. where he lived a good life until his death. However Smokey is still the Forest Service representative in public service announcements.
More info than you ever wanted to know about Smokey is available at www.smokeybearestore.com
Aloha, wow