Compact fluorescent light bulbs (CFLs) contain mercury, which is toxic if inhaled or ingested. Mercury is only released if the bulb is broken. It is important to properly dispose of CFLs and carefully clean up any breakage. If a bulb breaks, specific steps must be followed to safely clean up the mercury and prevent poisoning, including opening windows, shutting off air systems, calling the poison control center, and carefully following their instructions for cleanup based on the surface. The same precautions apply to other fluorescent bulbs and thermometers containing mercury.