14 November 2010

Autumn re-runs; Break a CFL? Don't panic.

This post ran originally on 23 April 2009. Few things irritate me more than panic spawned by ignorance and scientific illiteracy. A shocking amount of pseudo-scientific nonsense gets run as gospel by the Huffington Post, almost as much as the nonsense spewed out by Fox News. Ignorance and panic peddling know no politics.

Math and science are how human beings come to understand the world. For some reason that perspective's considered to be suspect by a lot of people. I will never understand that suspicion. The world's a dangerous place and removing all danger is impossible. Furthermore, everything is a potential toxin, everything. So much so that the term toxin is meaningless. Toxicity is dose. Period. Sure, drinking a cup of mercury will kill you, but so will drinking a gallon of water in a half an hour. Should we ban water because it's a toxin? Individual CFLs aren't a problem. A landfill full of them is. So use them, be sensible and recycle them once they're burned out.

The key to all of this is to understand what level of exposure to something is unlikely to cause harm. That's not information you're going to get from the Huffington Post, Fox News or anybody else who has an interest in you being scared. Science is your friend.

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. 


  1. Thank you for being a voice of reason!

  2. It's my calling Linda I swear. I just read a report yesterday that staring at a bright white LED light can damage the retina. Duh. Stare into the sun and watch what happens. Why would someone stare into an LED, or any light source for that matter, in the first place?

  3. Paul thank you, too much already to be concerned about, no need to add to it all!!


    Art by Karena

  4. I'm glad you got something from all of my convoluted math up there. I wish more people concentrated on real problems rather than made up ones.


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