Ask Mr. Green: Mercury in Fluorescent Bulbs

Hey Mr. Green,

What about the mercury in the fluorescent bulbs, and what do you suggest if one falls and breaks?

—Donna in Ojai, California

Your concern is shared by many others, judging by the number of questions I keep getting about mercury in bulbs.

The bottom line is that mercury in fluorescent bulbs does not add to the total amount of mercury in the environment, and they may even reduce it.

To set things straight, you simply have to compare the lives of a fluorescent and an incandescent bulb as follows: A) Because our coal-burning power plants emit around 50 tons of mercury each year, and because we use a staggering 3.9 trillion kilowatt hours a year, each kilowatt hour is, on average, responsible for emitting around .012 milligrams of mercury. B) A 13-watt fluorescent can replace the light of a 60-watt incandescent. C) Therefore, in 8,000 hours of use—the typical lifetime of a fluorescent lamp—a 13-watt fluorescent will be responsible for emitting an average about 1.25 milligrams of mercury at the power plant. By contrast, operating a 60-watt incandescent for the same amount of time will be responsible for 5.75 milligrams of mercury. D) A fluorescent lamp typically contains about 4 or 5 milligrams of mercury. Therefore, even if the fluorescent bulb is thrown into the garbage there is little or no more total mercury released on average than would be emitted from coal burned to power the lamp. (Actually, the fluorescent will account for less than the full 4 or 5 milligrams, because not all the original mercury is released anyway, as a considerable amount is bound to other substances in the lamp.) Moreover, newer fluorescents contain less mercury, with some down to only 1 milligram, which takes the possible net mercury emission from fluorescents well below that caused by incandescents. Of course if the bulb is properly recycled, then the mercury content is even less of a concern. 

Yes, fluorescent bulbs must be recycled, and I do wish that the manufacturers would state this more emphatically on their packaging. If you don’t know where to take the dead ones, go to earth911.com to find the nearest location.

Okay, that’s all well and good in general mathematical terms, but what if you bust a bulb right in your own home, and it falls onto the carpet where toddlers crawl and cats sprawl? That’s obviously different from having mercury gradually evaporating from a faraway power plant. But don’t panic. If you break a fluorescent bulb, the first thing to do is open doors and windows to the outside, shut off the heat or air conditioning, and leave the room for 10 minutes. This allows vaporizing mercury to escape. Then do a careful cleanup, following the EPA’s super-cautious procedures. Go print it out now and put it in a place where you can find it.

As noted, the EPA is being cautious. The mercury released by a busted bulb doesn’t go into the air in one toxic sigh, and not much of it can possibly get breathed in before it dissipates. So clean up a broken bulb, but don’t freak out. The stress might be worse for your health than the mercury. Now if you break something like one of those mercury thermometers, you’ve got some real trouble, because they contain 120 to 450 times as much mercury as a fluorescent bulb. In the event of release of this amount, follow the EPA cleanup guidelines as fast as possible.

Finally, to put things in perspective, the biggest worry about mercury is the amount emitted by power plants and other industrial processes. The EPA is proposing stricter limits on emissions, but of course faces the usual opposition from businesses that claim it’s too expensive to cut the pollution. If you want stricter rules on mercury and other pollutants, sign the Sierra Club’s petition to keep soot, smog, and mercury out of your air. After all, it's still your very own, unprivatized air.

Got a question? Ask Mr. Green!

This week on the Green Life, we're revisiting some of Mr. Green's greatest hits. This column originally appeared on January 23, 2011. 

 --illustration by Little Friends of Printmaking