T5 fluorescent lights last for up to 20,000 hours, according to Facilities Net. Metal halide lights are designed to last for the same amount of hours. Metal halide lights produce more visible light than T5 fluorescent lights. A metal halide light can emit around 38,000 lumens, while a T5 fluorescent light can emit only around 5,000 lumens, according to First Source Light.
Both types of lights contain elemental mercury. All types of fluorescent lights may contain an average of 5 mg of mercury, according to Earth Easy. Metal halide lights may contain around 38 mg of mercury. The Environmental Protection Agency warns that elemental mercury remains a toxic material. Mercury exposure can lead to dizziness, muscle atrophy, respiratory failure or death in extreme cases.
Both types of lights produce white to whitish-blue light. Four 54-watt T5 fluorescent lights produce a similar amount of light output to one metal halide, 250-watt light. Pro Lighting claims that four 54-watt T5 lights require 239 watts to operate, compared to a metal halide light that requires 454 watts to operate.