Lisa Sharkey had a piece in yesterday's Huffington Post where she described her panic over a broken compact fluorescent light bulb in her home. She then listed a series of clean up procedures that could only have been written by a personal injury attorney. Sheesh. Calm down already!
All fluorescent light bulbs contain elemental mercury. That includes the long, skinny ones in offices and schools. Elemental mercury is a naturally-occurring heavy metal that's also a neurotoxin in high enough doses. Elemental mercury is a liquid at room temperature and it evaporates into a gas easily. That gas glows when electricity passes through it. Hence its use in light bulbs. Mercury has a long list of practical uses and is found in everything from Mercurochrome to mascara. High concentrations of elemental mercury are more damaging as a gas than as a solid, so there are some sensible precautions you'll want to take should you break one of these bulbs.
But let's get a little perspective first and do some math.
Let's say you break a CFL containing five milligrams of mercury in your child’s bedroom. Further, let's say that bedroom has a volume of 25 cubic meters (that's a medium-sized bedroom). For the sake of illustration, let's assume that the entire five milligrams of mercury in the bulb vaporizes immediately. This would result in an airborn concentration of 0.2 milligrams per cubic meter. This concentration will decrease with time, as air in the room leaves and is replaced by air from outside or from a different room. So even if you do nothing, the concentrations of mercury in the room will likely approach zero after about an hour or so.
Under these relatively conservative assumptions, this level and duration of mercury exposure is not dangerous, since it's lower than the US Occupational Safety and Health Administration (OSHA) standard of 0.05 milligrams per cubic meter of metallic mercury vapor averaged over eight hours.
To equate the level of exposure in our broken bulb scenario with OSHA's eight-hour standard Imagine the immediate level of mercury in the room immediately after the bulb broke to be 0.2 milligrams of mercury per cubic meter. If we assume the air in the room changes every hour, then the eight-hour average concentration would be .025 milligrams per cubic meter.
See? No need to panic. While I wouldn't call it harmless exactly, it's not something you need to call a Hazmat team over.
So, in the event that you break a CFL, open a window to speed up the dispersal of the mercury vapor. If it makes you feel better, leave the room for a half an hour. Then come back and clean up the broken glass.