Most discarded MCLs (about 80%) and MCDs come from commercial and governmental facilities, while the rest are generated from households and other residential buildings. Many commercial and governmental facilities do periodic relamping to improve the energy efficiency of their buildings and to save on energy costs. These efforts are to be encouraged as reductions in energy use may also have benefits in respect to lower emissions (including mercury) from certain fossil fuel power plants.

Mercury Containing Lamps (MCLs): Using US EPA and manufacturer data, the annual discards of fluorescent lamps, which make up the vast majority of MCLs, and MCDs for Florida have been estimated since 1995. About 39 million fluorescent lamps were estimated to be discarded in Florida in 2002. Four-foot fluorescent lamps, the most common type of fluoresent lamp sold, were estimated to have an average mercury composition of about 10 milligrams (mg) per lamp based on the lamp manufacturing industry's data. Prior to 1994, new fluorescent lamps sold in the US were reported by this industry to contain an average of about 41.6 mg. Beginning in 1994, this average dropped to about 22.8 mg of mercury per this lamp type. Fluorescent lamp manufacturers have continued to reduce the amount of mercury their lamps contain through source reduction, and the average mercury content in four-foot fluorescent lamps dropped to about 8 mg in lamps made in 2001. This would be about an 80% reduction in the mercury content of these lamps over the last ten years. Based on an average lamp life of four years, fluorescent lamps that are discarded beginning in 2005 will be assumed to have an average mercury concentration of about 8 mg.

Mercury Containing Devices (MCDs): Florida's current estimates of discarded MCDs and the mercury they contain comes from a variety of sources including US EPA reports and manufacturer-reported information. The types of MCDs included in Florida's estimates are mercury-containing thermostats, thermometers, and electric switches (e.g., light switches, displacement relays, and boat bilge pump float switches). Since 1997, MCDs have been the largest source of mercury in Florida's MSW stream. The chart above and table below show the mercury in MCLs and MCDs that are estimated to have been discarded in Florida's MSW since 1995 in comparison with other sources. For more information on the sources of mercury in Florida's MSW, see Chapter 5 "Special Wastes" of the "Solid Waste Management in Florida 2001-2002 Annual Report."