Sales of compact fluorescent lightbulbs, or CFLs, have doubled in the last year. They’re great energy savers but there are things you need to know about them.

On rare occasions, the bulb can fail dramatically just before it burns out.  It can flash and make noise or smoke.  Underwriters Laboratories, which investigates products for safety, says UL-listed CFLs are not fire hazards.  And manufacturers say they are making circuitry changes so dramatic failures won’t happen.

If your CFL has a dramatic end, Consumer Reports recommends the following steps: CFLs do contain small amounts of mercury. So if a bulb breaks, follow the guidelines of the Environmental Protection Agency:

Used CFLs that are not broken should be recycled. For recycling information, check with your local sanitation department or go online to epa.gov/bulbrecycling.