Although mercury is present naturally in the environment, human activity contributes the majority of mercury releases. Commercial and industrial boilers emit mercury when they burn coal and oil to generate energy for manufacturing processes.
Incinerators emit mercury when they burn wastes containing mercury.
For medical waste incinerators, mercury comes from medical devices like thermometers and blood pressure devices. For municipal waste incinerators, mercury is in discarded appliances like fluorescent lights, lamps, and thermostats. These plants used a total of 165 tons of mercury in 1995, but only reported releasing 7 tons. Since the plants do not incorporate mercury into their product, EPA is working to determine what happens to the missing mercury. When EPA finds the missing mercury, we may learn that these plants are one of the top mercury emitters to air nationally.