WASHINGTON – A proposed Environmental Protection Agency rule limiting power plants’ carbon emissions got a big thumbs-up from environmentalist Rep. Henry Waxman Thursday at a rally outside the EPA building.

The California lawmaker and top Democrat on the House Energy and Commerce Committee spoke in support of the rule to set emissions limits on coal-fired plants outside the EPA headquarters as the agency heard public comments inside the building.

The rule, which is part of President Barack Obama’s climate change agenda, would impose restrictions on the amount of carbon pollution released from coal-fired power plants. It would be the first rule targeted at limiting greenhouse gas emissions from such plants. It would limit emissions to 1,100 pounds of carbon dioxide per megawatt-hour, which would cut emission by about 40 percent, according to the Congressional Research Service.

Under the rule, new coal-burning plants would have to install carbon-controlling technology to prevent some emissions from being released into the air.

Plants that burn fossil fuels like coal are the largest source of carbon pollution in the U.S. Opponents complain the rule could force many power plants to shut down.

Waxman called the rule “reasonable as well as necessary.”

“It’s very simple,” Waxman said. “If we’re going to avoid the climate disasters that we’re now experiencing … we must regulate the cause of climate change which are carbon pollution and greenhouse gases.”

Waxman, who has said he will retire when his term ends this year, is a well-known environmental activist in the House. In 2013 he formed the Safe Climate Caucus with 34 other representatives to address climate change issues.

Earlier Thursday, Waxman announced the caucus will increase its online presence through articles in The Huffington Post and videos on YouTube.

Waxman was joined on Thursday by Elena Rios, president of the National Hispanic Medical Association, who spoke about the public health dangers of climate change.

Minority and low-income communities are disproportionately hurt by these health risks, Rios said.

Nick Mullins, a former fourth-generation coal miner who moved away from his hometown in southwestern Virginia because of the effects of the coal industry in the area, said the industry is exploiting the Appalachian region both economically and environmentally.

“No one in this great nation should have to make the choice between living in the place they called home for generations, or risking their children’s health by staying there,” Mullins said.

The EPA will accept public comments on the proposed rule through March 10 before making a decision.