Massachusetts Attorney General Maura Healey is urging the U.S. Supreme Court to uphold a federal rule aimed at reducing mercury and other pollutants from coal and oil-fired electric power plants.

Healey said the standards adopted by the Environmental Protection Agency are needed to protect the public from exposure to mercury which can be particularly hazardous to children and women of child-bearing age.

Healey's comment came as the court heard oral arguments Wednesday in a challenge to the rule brought by industry groups and 21 Republican-led states.

Healey has filed a multi-state brief in support of the rule, which aims to reduce power-plant mercury emissions by 75 percent in 2015.

She was joined by California, Connecticut, Delaware, Illinois, Iowa, Maine, Maryland, Minnesota, New Hampshire, New Mexico, New York, North Carolina, Oregon, Rhode Island, and Vermont.