When coal is burned, mercury is released in the air and water. It reaches our lungs directly or contaminates the fish we eat, and once inside us, it becomes a neurotoxin that can interfere with our brains and nervous systems. Mercury is especially dangerous for pregnant women, because in high enough doses, it can cause mental retardation and cerebral palsy in newborns - and in low doses it might slow a child's brain development.

These frightening dangers have been suspected for decades - and confirmed more than a dozen years ago. That's why we applaud the Environmental Protection Agency's new rules, announced Wednesday, to finally limit mercury and other toxic air pollutants produced by coal-fired power plants.

The new standards will require U.S. utilities to put into use pollution control technologies that will reduce harmful emissions. The safeguards are expected to clean up 90 percent of mercury pollution from power plants, which are responsible for about half the mercury released in the U.S.

Unfortunately, the EPA needed the nudge of a court order - and about 20 years - to issue the rulings. In 1990, provisions were included in the Clean Air Act to study the health effects of mercury and what technologies were available to control it. Eight years later, the EPA issued a study about mercury's dangers, and seven years after that, in 2005, the agency issued regulations that were so lame a federal court eventually tossed them and told the EPA to try again.

The new standards, while tardy, get it right. As expected, they've prompted objections from utilities and conservatives, some of whom seem to reflexively oppose any regulation, even those that save lives. The complaints this time involve cost, mostly, along with the three-year deadline the EPA will give most utilities to comply. That rush could result in brownouts, critics say, although several studies, including an Associated Press survey of power plant operators across the country, conclude that utilities will manage to keep our lights on.

Will it be expensive? Yes, which surely means that consumers will feel a sting, too. Duke Energy estimates that it'll spend $5 to $6 billion on pollution upgrades in the next decade throughout its five-state territory. The EPA says the new rules will cost utilities about $11 billion a year, which translates to a $3 to $4 increase in a typical monthly residential bill. It could easily be more.

But it could be worse. More than half the nation's coal-fired plants already have adequate pollution-catching technology, thanks to state regulations and some wise foresight. That includes many Duke and Progress Energy plants, which benefited from N.C. lawmakers smartly passing the 2002 Clean Smokestacks Act that forced utilities to install better pollution controls.

Here's why the additional new rules are worth it: The EPA estimates they will prevent about 11,000 premature deaths a year, more than 100,000 cases of childhood asthma and countless cases of childhood bronchitis, adult-onset asthma and other illnesses. Those estimates could be high, as critics allege, but opponents of the regulations offer no science to counter the EPA.

What we know is that mercury's danger is real, and that the cost of controlling that odorless, invisible poison pales against the cost of doing nothing. We're thankful the EPA has finally concluded the same.