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Ask the Experts

CFL Light Bulb Safety

by Berkeley Wellness  

Q: Are compact fluorescent light (CFL) bulbs safe to use? I heard they produce ultraviolet light and mercury fumes.

A: These energy-efficient bulbs are safe when used as directed. All types of fluorescent bulbs contain mercury vapor, which emits ultraviolet (UV) rays when exposed to an electric current. That UV is absorbed by a layer of phosphor on the inside of the bulb, which produces visible light. But lab experiments have shown that CFLs do emit some UV, sometimes enough to damage skin cells placed directly under them. That may be, in part, because the phosphor coating almost always has cracks and chips, researchers have found, which allows some UV to pass through.

Distance is key, however. Even when CFLs release UV, this will cause little or no damage if the bulbs are farther than a foot or two away from your skin. In fact, testing by the Canadian government in 2009 found that at distances greater than 11 inches, UV from CFLs is no greater than that from standard incandescent bulbs (yes, these also produce tiny amounts of UV; halogen bulbs produce the most). In addition, if the bulbs are behind glass, plastic, or a shade, UV transmission is greatly reduced or eliminated.

Best advice: Don’t keep your bare skin within a foot or two of an unshielded CFL for more than short periods, and don’t stare directly into it.

As for mercury, the risk occurs if a bulb breaks open. CFLs contain less than 1/100th of the amount in a mercury thermometer, and only a fraction is released as vapor when a bulb breaks. But no mercury exposure is safe.

Take care when handling CFLs. If you break one, open a window to air out the room for 10 minutes. Then, wearing disposable gloves, use stiff paper to scoop up the broken glass and powder, or use damp towels or sticky tape (don’t vacuum, since that can spread the powder or vapor). Dispose in a sealed plastic bag or container. For more detailed instructions, see the EPA's advice on what to do if a CFL breaks.

When a CFL burns out, seal it in a plastic bag and dispose of it via your local waste collection agency. Some hardware supply stores and other retailers offer in-store recycling (you can search for a recycler near you on the Earth911 website).

By the way, the market for CFLs has been shrinking dramatically as Americans turn to even more energy-efficient LED (light-emitting diode) bulbs, which have improved in quality and dropped in price. In fact, General Electric will stop making CFLs at the end of this year. LEDs contain no mercury and emit virtually no UV. However, LEDs do produce some blue light, which can interfere with sleep.