Mercury & compact fluorescent (CFL) bulbs

I like to encourage people to switch their incandescent lights to CFLs because they will save so much electricity, money, and greenhouse gases. People have told me that they worry they should not get compact fluorescents because they have heard of the negative environmental impacts, especially from mercury and from energy used in production of the bulbs, and they have asked me if this is a problem. Since I did not know the answer, I did some research. My recommendation after doing the research is still to replace your incandescents with compact fluorescents. I also now recommend you dispose of used CFLs properly.

According to EPA's Energy Star program, CFLs do contain small amounts of mercury- usually about 5 milligrams, the amount that would fit in the ball of a ballpoint pen. The average old thermometer has 500 mg of mercury. A number of manufacturers have committed to reduce the mercury in CFLs. CFLs pose no threats from mercury unless they break. A perspective on CFLs and mercury from Professor Sue MacIntosh, Professor of Environmental Health, Harvard University:

A CFL containing 5 mg of mercury breaks in your child’s bedroom that has a volume of about 25 m3 (which corresponds to a medium sized bedroom). The entire 5 mg of mercury vaporizes immediately (an unlikely occurrence), resulting in an airborne mercury concentration in this room of 0.2 mg/m3. This concentration will decrease with time, as air in the room leaves and is replaced by air from outside or from a different room. As a result, 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 likely to be dangerous, as it is lower than the US Occupational Safety and Health Administration (OSHA) standard of 0.05 mg/m3 of metallic mercury vapor averaged over eight hours.

Ironically, coal fired power plants emit mercury, and using CFLs reduces the amount of electricity used and therefore the amount of mercury emitted. The Maryland Sierra Club calculated an estimate of the amount of mercury emitted per kilowatt hour of electricity production in Wisconsin and came up with .023mg/kWh. They then looked at the average amount of mercury in a CFL and came up with 5.1mg. They figured out that a 100 watt incandescent bulb over 10000 hours (replaced 10 times because it lasts 1000 hours) will cost $105.50 in electricity and bulbs, and result in coal-fired plants emitting about 23 mg of mercury and about 2,000 pounds of CO2, a greenhouse gas. Both Incandescent and CFL bulbs also often contain lead solder, a powerful toxin. A 100 watt equivalent CFL (23 watt) will cost about $25.50 in bulbs and electricity, last 10,000 hours, emit about 5.2mg of mercury (plus the 5.1mg stored in the bulb for a total of 10.3 mg) and emit 460 lbs of CO2. CFLs are cheaper. When coal-fired plants produce electricity, CFLs are responsible for less mercury and much less carbon dioxide emissions than incandescents. Popular Mechanics crunched the numbers on mercury as well:

Approximately 0.0234 mg of mercury—plus carbon dioxide, sulfur dioxide and nitrogen oxide—releases into the air per 1 kwh of electricity that a coal-fired power plant generates. Over the 7500-hour average range of one CFL, then, a plant will emit 13.16 mg of mercury to sustain a 75-watt incandescent bulb but only 3.51 mg of mercury to sustain a 20-watt CFL (the lightning equivalent of a 75-watt traditional bulb). Even if the mercury contained in a CFL was directly released into the atmosphere, an incandescent would still contribute 4.65 more milligrams of mercury into the environment over its lifetime.

According to Earth911, CFLs take five times the energy of incandescent bulbs to produce. CFLs last ten times as long, so they use half the energy of incandescents in production.

Note a number of household appliances contain mercury. My old thermostat that I recently replaced contains a whopping 3 grams of mercury in a glass tube. It's sitting in a box waiting for the next household hazardous waste day.

Note some states prohibit the disposal of CFLs in the trash and require the bulbs to be taken to a recycling center or to a household hazardous waste collection. This is not the case in Maryland. Some places will recycle CFLs- to see if there is a program near you, visit Earth911. Here is some more info about CFL recycling in MD from the Sierra Club:

Montgomery County residents can dispose of CFLs at its transfer station and at special hazardous waste collection events. The City of Takoma Park accepts used CFLs at its public works building on Oswego Avenue during business hours and in a drop box at other times. Ikea stores have recycling stations that accept light bulbs, batteries, and plastic bags.

EPA suggests the following for broken bulbs: If a bulb breaks, air the room for 15 minutes. Do not touch the bulb with bare hands. Sweep up the mess. Wipe the area up with wet paper towels. Do not vacuum hard surfaces. Seal the broken bulb in a plastic bag and the wiping materials in another bag and dispose in the trash.
I hope that helps.