The level of mercury contained in each different type of mercury-containing light bulbs can vary dramatically. Standard fluorescent light bulbs of varying wattages all contain around 5 mg of mercury. High-pressure 250-watt sodium light bulbs can contain around 15 mg of mercury. Metal halide 250-watt light bulbs contain more mercury than any other type of light bulb, around 38 mg.
Even limited exposure to mercury can have detrimental effects on a person's health. The EPA (Environmental Protection Agency) claims that exposure to small amounts of mercury can result in certain symptoms like tremors, mood swings, nervousness, insomnia and muscle atrophy.
The EPA recognizes and warns that overexposure to mercury can be fatal. Overexposure to the type of mercury found in many newer types of light bulbs can result in kidney failure, respiratory failure and, in extreme cases, death.
There are several factors associated with how severe of a reaction a person may experience after being exposed to mercury. Factors include the form of mercury a person is exposed to (in this case, elemental mercury), age (fetuses are the most susceptible), duration of exposure, route of exposure (ingestion, inhalation, dermal contact) and the general health of the person exposed.
In cases where a mercury-containing light bulb breaks, all parties in the same room as the broken light bulb should exit the room immediately. The mercury should be given time to dissipate throughout the room before it is approached, around 15 minutes. If possible, open a window before exiting the room.