What is Mercury?
Mercury is a neurotoxin.
- elemental (metallic) mercury,
- inorganic mercury compounds, and
- methylmercury and other organic compounds.
- the form of mercury (for example, methylmercury or elemental (metallic) mercury);
- the amount of mercury in the exposure;
- the age of the person exposed (unborn infants are the most vulnerable);
- how long the exposure lasts;
- how the person is exposed — breathing, eating, skin contact, etc.; and
- the health of the person exposed.
– United States Environmental Protection Agency
Emissions of Mercury into the air
Mercury becomes a problem for the environment when it is released from rock and ends up in the atmosphere and in water. These releases can happen naturally. Both volcanoes and forest fires send mercury into the atmosphere.
Human activities, however, are responsible for much of the mercury that is released into the environment. The burning of coal, oil and wood as fuel can cause mercury to become airborne, as can burning wastes that contain mercury.
This airborne mercury can fall to the ground in raindrops, dust, or simply due to gravity (known as “air deposition”). The amount of mercury deposited in a given area depends on how much mercury is released from local, regional, national, and international sources.
Emissions from Power Plants
Since mercury occurs naturally in coal and other fossil fuels, when people burn these fuels for energy, the mercury becomes airborne and goes into the atmosphere. In the United States, power plants that burn coal to create electricity are the largest source of emissions; they account for about 44 percent of all manmade mercury emissions
Other causes of Mercury Air Emissions
- Burning oil that contains mercury
- Burning wood that contains mercury
- Burning mercury-containing wastes, including
- wastes from the manufacture of Portland cement
- consumer products that contain mercury, like electronic devices, batteries, light bulbs and thermometers, that are thrown into garbage that is incinerated
- Using certain technologies to produce chlorine
- Breaking products that contain mercury
- Burning iron ore, coke and limestone in electric arc furnaces used to produce steel
- Using coal-fired boilers in many industries to generate forms of thermal heat like steam
The burning of municipal and medical waste was once a major source of mercury emissions. A reduction in the use of mercury along with state and federal regulations, however, has led to a decrease in emissions from this source by over 95%
Clean Air Act
The Clean Air Act regulates 188 air toxics, also known as “hazardous air pollutants.” Mercury is listed as one of these air toxics. The Act directs EPA to establish technology-based standards for certain sources that emit these air toxics. Those sources also are required to obtain Clean Air Act operating permits and to comply with all applicable emission standards.
The law includes special provisions for dealing with air toxics emitted from utilities, giving EPA the authority to regulate power plant mercury emissions. The Agency can do this by establishing “performance standards” or “maximum achievable control technology” (MACT), whichever the Agency deems most appropriate.
Mercury Contamination Detection
Your Mercury Guide is available for download.
In this Guide, you will learn about the Properties | Exposure | Detection of Mercury.