Naturally Occurring Mercury

Mercury in the Earth’s crust is released through the natural weathering of rocks, geothermal activity, and volcanic eruptions. Forest fires also discharge mercury into the environment.

Human-Generated Mercury

According to the United Nations Global Mercury Assessment in 2018, “Human activities have increased total atmospheric mercury concentrations by about 450% above natural levels”.

During the late 19th century, humans began using more and more fossil fuels to run factories, power transportation (trains and cars), and for home use (heat and cooking). Today, the primary cause of mercury emissions in the United States is human activity involving the burning or processing of fossil fuels (coal and oil) for energy.

Globally, today, gold mining is the largest source of human-generated mercury emissions (mercury is used to extract gold from rocks) and the major contributors to mercury emissions are countries in South America and Sub-Saharan Africa.