CFL bulbs do contain trace amounts of mercury. But there is actually six times more mercury in the battery in your watch than in a CFL bulb. If a bulb breaks in an enclosed area, open a window for a bit. Pick up small pieces with masking tape rather than the vacuum. Put broken bulbs in a plastic bag, or the box the bulb came in. Recycle old bulbs at the same place you recycle motor oil or old batteries.