Dear Umbra,

We have been replacing our incandescent light bulbs with compact fluorescent bulbs, but we notice that the compact fluorescents have an odd smell. Are they emitting something we should know about? Compact fluorescent bulbs contain mercury; can the bulbs discharge the mercury into the air?

Tom Murphy
Wellsboro, Pa.

Dearest Tom,

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I don’t know of anything that would be emitted from your bulbs and smell. If it is your CFL giving off an odor — not something evaporating or burning in the lampshade or socket — it may be from the plastic, and it should go away. But rest easy: there is no way it’s the mercury.

What’s that smell?

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For one thing, mercury is odorless. For another, if the mercury were leaking, the lamp would not be working. (FYI, your question led me to discover an entire line of compact fluorescent bulbs designed to eliminate odors, and accolades from cat lovers about litter-box smell disappearance!)

Let’s address the mercury issue looming over CFL users ’round the nation. At room temperature and regular atmospheric pressure, mercury is an odorless liquid. Last week I wrote, with my usual scientific precision, about CFLs and the little gas-filled tubes they contain. The pressurized tube is where the infamous mercury lurks. Under the conditions inside the tube, it becomes a gas that helps to light your house.

Compact fluorescents contain only a wee bit of mercury — four to five milligrams, compared to 500 milligrams in a thermometer — but even that amount is highly poisonous. If you were to break your CFL, the mercury could take the form of a metallic amoeba of toxic, vapor-emitting fun. You can inhale the gas, and it’s worse if the room is poorly ventilated. As you attempt to clean it all up, little balls can break off and sneak into your floorboard or carpet fiber, lurking in wait to poison the entire family, from the cat to grandma, odor or no. So don’t be casual about light bulb or thermometer breakage. Follow EPA’s cleanup instructions. If you cut yourself in the process, call a doctor. And don’t let children play with mercury. (Even though we all had such fun doing it when we were kids.)

All that said, keep buying compact fluorescents and don’t worry about the mercury, so long as it stays inside the bulb. When the bulbs die, bring them to the hazardous-waste people.


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