Compact fluorescent light bulbs contain mercury and need to be properly disposed of. Household compact fluorescent light bulbs (CFL) have become increasingly popular in recent years. Compared to incandescent light bulbs, CFLs are generally several times more efficient and have a longer rated life. Despite the improved efficiency, the actual environmental effect of CFLs is the subject of much debate. CFLs typically use mercury vapor and need to be properly disposed of. Here a household CFL package sold in the USA by General Electric is shown. September 2007.