Mercury is a powerful neurotoxin that can cause lasting damage to the brain, lungs, skin and other organs. Children are especially vulnerable to severe developmental harm from exposure.
A naturally occurring trace element, mercury is present in rocks such as limestone and in fossil fuels like coal and crude oil. While it has been locked underground for millions of years, human activities—most notably burning fossil fuels—release mercury into the environment.
Coal-fired power stations are a major source of this pollution. Coal contains only trace amounts of mercury, but the enormous volumes burned make total emissions significant. The communities nearest many plants—often low-income or marginalized—frequently shoulder the heaviest burden. Once emitted, mercury can persist in the atmosphere for more than six months, then deposit onto soil and into water where it enters food webs and bioaccumulates. Tiny concentrations transported up the food chain can pose real risks to human health.
Policy choices can have large health and economic consequences. In April 2025, the U.S. administration granted nearly 70 coal plants two-year waivers allowing them to exceed air pollution limits, including for toxic pollutants such as arsenic and mercury, citing harms to the energy industry from tighter Biden-era standards. Yet a 2024 Environmental Protection Agency assessment found that industrial air-pollution rules could reduce health-care costs by roughly $390 billion over two decades. The Natural Resources Defense Council also estimates that the Biden-era limits prevented about 11,000 premature deaths, and that stronger standards could sharply cut mercury emissions from coal-fired sources.
The mercury problem is linked to climate change. Burning coal is a major driver of greenhouse gas emissions, and warming threatens to release mercury stored in frozen soils: nearly half of the planet’s natural mercury is held in permafrost, which could emit both greenhouse gases and long-trapped mercury as it thaws. Continued coal use and weakened pollution limits therefore aggravate the problem on two fronts. Still, available technology can substantially reduce mercury emissions: Germany’s NABU estimates up to 85% of coal-related mercury releases can be prevented with current controls, and the NRDC points to possible reductions approaching 90% under stricter standards.
For people, the primary exposure route is through eating fish and shellfish. Microbes such as algae and zooplankton convert inorganic mercury into methylmercury, a highly toxic form that accumulates in organism tissues. Predatory fish concentrate higher levels over time, and humans who eat contaminated seafood can accumulate dangerous amounts. A U.S. survey found that up to 19 million people who consume self-caught fish three or more times per week may face mercury exposures high enough to harm health. Importantly, once mercury has accumulated in the body it does not break down.
Edited by: Tamsin Walker