What are Mercury and Air Toxics Standards?
The Mercury and Air Toxics Standards (MATS) set limits on three pollutants: mercury, hydrochloric acid, and particulate matter. Since the standards went into effect about a decade ago, mercury pollution from coal-fired power plants has decreased 90 percent through a combination of pollution-controlling technologies, plant closures, and changes to cleaner fuel sources. Such declines, Sunderland figures, translate to billions in public health savings. “MATS were overwhelmingly successful,” she says.
The Clean Air Act also requires the EPA to periodically review whether available technologies have improved to a degree that would warrant strengthening the standards, says John Walke, NRDC’s clean air director, who has been working on mercury pollution issues for more than two decades. Despite previous efforts by the Trump administration to roll back MATS, that tech review is now moving forward and addressing the fact that certain technologies are now known to work better on different types of coal. This is especially significant for the current weak standards for power plants that burn lignite coal, which contain especially high levels of mercury.
“The rationale at the time was that it was harder to control or limit or reduce mercury from the combustion of lignite coal. Subsequently, we’ve learned that’s not really true. The proper technologies can actually do it quite effectively,” says Walke.
Why stronger mercury standards are necessary
The majority of coal-burning power plants nowadays emit 5 kilograms of mercury per year, according to Sunderland. This keeps exposures within the EPA’s acceptable threshold for most people. Still, as Sunderland puts it, “there is no safe level of mercury exposure.” And there are clusters of lignite-burning power plants in North Dakota and Texas, for instance, with annual mercury emissions of more than 100 kilograms. The pollution spewing from these plants is unacceptable and also unnecessary.
Relatively inexpensive technologies, such as activated carbon injection, can lower the amounts of mercury and other heavy metals, like lead and arsenic, being emitted from lignite coal, and stronger MATS would require these upgrades. Without them, the people living near these plants—such as the Indigenous communities of North Dakota’s Fort Berthold and Spirit Lake reservations—will continue to contend with a potent neurotoxin insidiously making its way through their soils, waters, wildlife, and food.
The EPA, says NRDC’s Walke, has decided that power plants “can do more, they should do more, it’s cost effective for them to do more, and it’s important for public health to do more.”