Function

• CFLs function by exciting a layer of fluorescent material on the interior of the bulb's glass tube with gases that emit UV radiation when subjected to an electrical current; the gas contains trace amounts of mercury, a toxic element.
  
  

Disposal

• Since CFLs contain mercury, they may pose a larger environmental threat that normal light bulbs and it is illegal to dispose of them in the normal trash in certain states.
  
  

Cleanup

• If a CFL breaks, cleaning the mess is complicated by possible mercury contamination; it is recommended to clear pets and children away from the mess and allow the room to air out for 15 minutes before going in to clean the glass.
  
  

Applications

• CFLs may not perform as well as normal light bulbs in hot and wet environments; CFLs can also take some time to reach full brightness, which makes them less useful for applications where light must be turned on and off constantly.
  
  

Cost

• Another drawback of CFLs is that they cost much more than standard light bulbs; energy savings can offset the cost difference, but if CFLs die early or break it is more costly to replace them.