Fluorescent Bulbs Trade Off Energy Savings For Mercury

Switching from incandescent to compact fluorescent light bulbs (CFLs) to save energy may increase atmospheric mercury emissions in some regions, according to a study by Yale University researchers (Environ. Sci. Technol., DOI: 10.1021/es800117h). Each CFL can release about 5 mg of toxic mercury if broken during use or disposal. Mercury also occurs naturally in coal and is emitted from coal-fired power plants. Julie B. Zimmerman and colleagues examined mercury emissions data collected in 2004 from 50 U.S. states and 130 countries to estimate the mercury trade-off of using CFLs. They found that mercury emissions during the life cycle of a CFL vary widely. In general, using CFLs appears to cut emissions by reducing use of coal-derived electricity, but where there is a small percentage of coal-based power generation and little to no recycling, the use of fluorescents may instead increase mercury emissions, the authors note. For example, Estonia, China, and West Virginia have the greatest potential for mercury emissions reduction, whereas emissions in California and much of South America and Africa could increase.