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The Facts about Light Bulbs and Mercury

Noah Long

Posted July 11, 2011

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Compact fluorescent lights (CFLs) use about a quarter of the electricity of traditional incandescent light bulbs, reducing energy costs for consumers.  By conserving electricity, CFLs also avoid some of the mercury emissions from power plants that burn coal. Burning coal is a far larger source of mercury in our environment and a far bigger risk to our health.  In fact, we’ve calculated that using a CFL results in less than half of the mercury emissions of using a 100 W incandescent light bulb.


However, CFLs themselves contain a small amount of mercury, which has led to some questions about whether they are safe to use. We’ve taken a close look at this issue, and we believe that CFLs are the right choice for those concerned about both their health and their energy bills.

The amount of mercury contained in a CFL is very small — a typical bulb today contains about 3mg.  To put that amount in perspective, there is up to five times that amount of mercury in the watch battery on your wrist; quite notably, between 60 to 200 times that amount of mercury in a single “silver” dental filling in people’s mouths, depending on the size of the filling; 100 to 200 times that amount in the old-style thermometers many people still have in their medicine cabinets; 200 times that amount per switch in the light switches of certain freezers; and about 500 times that amount in thermostats on the walls of people’s homes. (These are conservative estimates based on comparison to a bulb with 5 mg of mercury.) CFLs also use the same technology as the linear fluorescent tubes we have been using in our schools, offices and hospitals for over 50 years. Those tubes can contain up to 100 mg of mercury each.

Still, you may be concerned that a delicate glass bulb is different from the watch on your wrist: if a CFL breaks, some of the mercury inside can escape into your home.  Some news reports have raised concerns that broken CFLs could result in harmful air concentrations of mercury in the room where the bulb is broken, but  these reports are based on worst-case situations, assuming common sense measures (such as ventilating the room) are ignored.   If a bulb does break in your home, don’t panic.  The small amount emitted is unlikely to be harmful, and you can use simple cleanup procedures to further minimize any exposures.  Keep kids away from the breakage, open a window and carefully clean up the pieces and place them in a ziplock bag for proper disposal.  

While it is sensible to handle broken CFLs with care, by far the most important step people can take to reduce mercury exposure in their daily lives is to avoid eating fish contaminated with mercury. Eating fish is the main source of mercury exposure for Americans, and the form of mercury found in fish is more toxic than the form used in CFLs (or other household products).  While fish is part of a healthy diet, people should take care to choose the types of fish which contain the least amount of mercury, particularly if they are pregnant or nursing. NRDC’s website contains recommendations for choosing fish that contain the least amount of mercury. Visit for a printable shopping guide to safe fish.

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peter dublinJul 11 2011 06:40 PM

This one about coal mercury / CFL mercury keeps doing the rounds...
Even EPA are moving away from what you are saying...

Clearly, power plant mercury needs to be dealt with too
- but that is already being done under EPA admin Lisa Jackson, with
new technology -notice the EPA regulations just the other day, with
"scrubbers" that also reduce mercury emissions.

The reason why CFL mercury is a greater problem, is extensivel­y covered here, including USA EPA program references etc
= http://ceo­­i198x

Taking account therefore,
the fact that electricity does not just come from coal,
or that mercury release INSIDE a room is rather different from outside,
or that the supposed level of Energy and Lifespan usage advantage of CFLs have
recently been found not to hold up as assumed in the mercury comparisons made...
( )

In a nutshell

1. We know where the ever decreasing local coal power plant chimneys
are and we can treat their emissions with ever increasing efficiency
at lower costs.

2. Compare that with a broken CFL at home, with mercury release on the spot.

3. Also compare that with future billions of scattered broken CFLs
elsewhere, when we do not know where all the broken lights will be,
and so it is much harder and often impossible to do anything about them.

4. Also compare that with any recycling process of CFLs, with its own
mercury release,
and the mercury release of the CFL shipping transport from China (the
ships use Bunker oil),
and back again for new CFL manufacturing.

greenlanternJul 12 2011 06:18 AM

its really important that we phase out the conventional bulbs. they waste the energy.

Veg UfoJul 13 2011 07:57 AM

It's not clever to compare the "low" amount of mercury in a CFL with the high amount of mercury in dental fillings. They are under discussion and might be a big health issue. If you complain about PBA or know the tiny amounts of substances the endocrine system works with, such amounts of a high toxic metal in the mouth cannot not be without negative health effects. Future will show enough diseases linked to it. But industry funded studies will tell us, everything is OK.

Why not using LEDs? They save even much more energy. However they are an another example of plain technical thinking that focuses on performance and costs only and claims, it cannot be harmful if it doesn't hurt you immediately. LED light is pulsed, that's their method of energy saving. They put your eyes and brain on stress. It's a pity, because LED technology can produce nearly the full range of light spectrum.

If we look at the entire load of toxins and other stressors from a polluted environment, we should try to avoid every increase instead of comparing single values. Every little more mercury or other stuff is to much.

The old light bulb is not that bad. It produces beautiful light and may be the perfect winter lamp, when the sun is neglecting us. If you substract the heat they produce from your heating costs, the energy consumption for the light is not hight. Why not focus on clean energy instead of discussing the old fashioned light bulb. This discussion should also include discussion of decentralized power production. Large scale centralized technology always comes with risks and fulfills only the needs of big business. The sun offers more energy we need and it is free. So is the wind. There is only a lack of storage technology. This should be a challenge for science.

Off topic? Cars do even run with air:

Veg UfoJul 13 2011 11:40 AM

One correction: You have to add the costs for the heat the good old bulbs produce to your heating cost. Substract them from the light. Sorry for that mistake.

Janet SwitzerJul 16 2011 03:53 PM

What is "proper disposal" of broken CFLs? Usually this turns out to mean something that is not generally available.

CFLs creep me out and so do LEDs. This is hugely disappointing because, as one who has lived off-grid and loved it (great smug factor), I am all in favor of reducing energy use. So I achieve that by scrupulous use of the light switch.

peterdubJul 17 2011 11:22 AM

that is of course a very good point:

Light bulbs don't burn coal or release any fumes (hopefully!) - power plants might.

It's not like dealing with gasolene-powered cars, that do have such fossil fuel effects...

So, as in Janet's case,
(or more precisely, those who have their own energy sources, or get it from renewable solar, wind etc or even nuclear NON mercury or CO2 releasing sources)
why should she not be allowed to use what SHE wants?

There is still the argument that "power plants are built unnecessarily",
but that does not hold up on the basis that only c.2% of US grid electricity is saved by regulations (\li171x )
- or with the argument that she is paying for her electricity and its production, of course to whatever environmental standard that is required...

Having read some of your other posts,
(where commenting is closed)
I do agree that there are many good ways to save energy and emissions...
but energy efficiency regulation is not one of them, (eg with electricity = generation and grid upgrades more relevant and significant) and even if it was, taxation that cross-finances cheaper energy saving alternatives would be better
- eg California (which you had an earlier post on) = big govmt income, people keep choice, people use less energy demanding products, energy/environment programs are financed....
I would still favor free markets, but taxation is just another way that is still better than the regulations that NRDC push for...

And, If coal use is still such a worry = just tax it.
None of this complicated regulation rigmarole to reduce its use!

peterdubJul 17 2011 11:26 AM

small correction re above
the link re small energy usage, as referenced with DOE etc figures
(why no power plant would be saved in any case, )

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