Resisting strenuous last-minute lobbying by some of the nation’s biggest utilities, the Obama administration announced on Wednesday a final rule requiring power plants to reduce emissions of mercury and other toxic pollutants by roughly 90 percent within the next five years.

This is a big victory for environmentalists and scientists who have worked for 20 years to regulate these pollutants — and an even bigger one for the public. When fully effective, the rule could save as many as 11,000 premature deaths a year and avoid countless unnecessary illnesses.

The decision compensates, at least in part, for the White House’s lamentable decision two months ago to reject stricter health standards for smog. That and the administration’s failure to give full-throated support to climate change legislation last year had disheartened many of the president’s environmental supporters.

The administration can now legitimately point to three measures that will almost certainly lead to cleaner power plants and vehicles, more breathable air and fewer greenhouse gas emissions: a ruling in July setting new limits on interstate emissions of sulfur dioxide, the main acid rain gas; a landmark deal announced in November aimed at doubling automobile fuel efficiency by 2025; and, now, the new mercury rule.