Mercury Facts

There are natural and human-made sources of mercury in our environment. Natural sources of mercury are found in soils and rocks, forest fires and volcanic eruptions. More than half of the mercury in the environment comes from human sources such as burning coal to create electricity, burning trash, and improper disposal at landfills. Burning coal and trash releases mercury in the form of gas and particles into the air. Rain and snow bring mercury in the air back to the earth’s surface. Improper disposal causes mercury to get into the water and soil.

Humans are exposed to mercury through their diet, absorption, or through the inhalation of toxic elemental mercury fumes. Brief exposure may cause: coughing, shortness of breath, chest pain, nausea and bronchitis. Long-term exposure may cause: loss of muscle control, memory loss, central nervous system damage and kidney disease.

  • Because of the harmful effects of mercury to the environment and public health, Maryland passed legislation (House Bill 75) to address mercury pollution in the environment. This law prohibits the sale or provision of mercury fever thermometers. The law also prohibits the use of mercury in schools and requires the Maryland Department of the Environment (MDE) to provide outreach assistance to schools. MDE is also required to implement an outreach program related to hazards of mercury and voluntary efforts that individuals, institutions, and businesses can undertake to help further reduce mercury in the environment.
  • MDE has issued statewide advisories  for gamefish and panfish in all freshwater lakes, streams, and rivers and has also monitored mercury levels of numerous species inhabiting the Chesapeake Bay and other tidal waters.  The MDE has also provided Maryland residents with additional health information in a  public information brochure
  • Women who are pregnant, nursing or may become pregnant are advised to reduce or eliminate their consumption of certain types of commercial and recreational fish. Individuals can get the most current information on fish consumption advisories by contacting MDE Science Services Administration (SSA - formerly TARSA) at 410-537-3906.
  • Maryland House Bill 504 prohibits marketers from selling or providing electric switches, electric relays, and gas valve switches that contain mercury to a consumer on or after October 1, 2018.
  • CFL bulbs contain up to 5 milligrams of mercury, the amount that would cover the tip of a ballpoint pen, as compared to older home thermostats and mercury fever thermometers, which contain between 500 to 30,000 milligrams of mercury.
    • The Maryland Department of the Environment (MDE) urges consumers to use care when handling CFLs by screwing and unscrewing the bulb by the base. If a CFL bulb breaks, the amount of mercury released can evaporate into the air where it will likely remain at a level below safety standards set by the Occupational Health and Safety Administration.
    • CFL bulbs should be recycled after use whenever possible. We strongly encourage consumers to take advantage of available local recycling options for used CFL bulbs. Contact Howard Co. Environmental Services  Household Hazardous Waste (HHW) collection at 410-313-6444 for more details. 

Mercury sources in the home and the environment (EPA)

What to Do if a Mercury Thermometer Breaks?  Cleaning up A Mercury Spill (EPA)

To dispose of old mercury thermostats, it is recommended that a local thermostat collection site be utilized.

Local thermostat collection sites 

If there are any additional questions, please contact the Community Hygiene Program at (410) 313-1773.

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