A potent neurotoxin that can cause lifelong harm to the lungs, brain, skin and other organs, mercury is tightly regulated worldwide. Children are especially vulnerable to severe developmental damage from exposure.
Mercury is a trace element found naturally in rocks like limestone and in coal and crude oil. Locked underground for millions of years, it largely enters ecosystems through human activity and is released when fossil fuels are burned.
Coal-fired power plants are a major source of environmental mercury pollution. Although coal contains only small amounts of mercury, the volumes burned make these emissions significant. Communities nearest to power plants—often marginalized or economically disadvantaged—tend to bear the greatest burden. Once emitted, mercury can remain in the atmosphere for more than six months, depositing into water, plants and animals and moving up the food chain, where even tiny concentrations can harm human health.
Regulations could save billions
In April 2025, the US administration granted nearly 70 coal plants two-year waivers allowing them to exceed air pollution limits, including for toxic substances such as arsenic and mercury. The White House said Biden-era emissions standards harmed the energy industry. However, a 2024 Environmental Protection Agency assessment estimated that industrial air-pollution standards could save the health system about $390 billion over two decades. The Natural Resources Defense Council (NRDC) also estimates that Biden-era pollution limits prevented around 11,000 premature deaths and that stricter rules could cut mercury emissions from coal plants dramatically.
Mercury pollution can be minimized
Beyond its direct health effects, burning coal is a major driver of climate change, which in turn worsens the mercury problem. Nearly half of the planet’s natural mercury is stored in permafrost; as warming thaws these soils, they could release both greenhouse gases and long-trapped mercury. Thus, continued coal use and weaker air-pollution limits push the issue on two fronts. Still, technical controls can substantially reduce emissions: Germany’s NABU says up to 85% of mercury emissions from coal could be prevented with available technology, and the NRDC points to potential reductions of up to 90% under stricter standards.
Once in the body, it doesn’t break down
For people, the main exposure route is eating fish and shellfish. Microorganisms such as algae and zooplankton absorb mercury and convert it into toxic methylmercury, which accumulates in their tissues. Predatory species concentrate higher levels over time, and humans can accumulate significant amounts by consuming contaminated seafood. A US survey found that as many as 19 million people who eat self-caught fish three or more times per week may face mercury exposures high enough to harm health.
Once accumulated in the body, mercury does not break down.
Edited by: Tamsin Walker
