Which of the following lamps contains a poisonous gas and therefore sh

Which of the following lamps contains a poisonous gas and therefore should be disposed safely ?

Compact fluorescent lamp
Light emitting diode
Neon lamp
Halogen lamp
This question was previously asked in
UPSC CAPF – 2014
Compact fluorescent lamps (CFLs) contain a poisonous substance, mercury vapor.
Compact fluorescent lamps (CFLs) use mercury vapor within a glass tube. When electricity passes through, it excites the mercury vapor, producing ultraviolet (UV) light, which then excites a fluorescent coating on the inside of the tube, causing it to emit visible light. Mercury is a toxic heavy metal that poses environmental and health risks if released, necessitating safe disposal practices for CFLs.
Light-emitting diodes (LEDs) are solid-state devices that do not contain mercury or other hazardous substances found in traditional lighting like CFLs. Neon lamps contain neon gas at low pressure and are generally not considered hazardous in the same way as mercury vapor lamps. Halogen lamps are incandescent lamps containing a halogen gas (like iodine or bromine) within the bulb, which helps extend the filament’s life; they do not typically contain poisonous gases requiring special disposal related to toxicity.