* New EPA leader argues plan makes "business sense"
* McCarthy leads rollout of proposed regulations
By Environment Correspondent Deborah Zabarenko
WASHINGTON, Sept 20 (Reuters) - When U.S. environment chief Gina McCarthy talked about cutting climate-warming carbon emissions on Friday, she offered a translation for those unfamiliar with the dropped "R" of her thick Boston accent.
"I should make sure that everybody knows that when I say cahbon, it's c-a-r-b-o-n," McCarthy told a standing-room-only gathering at the National Press Club in Washington.
As the chuckles subsided, the new administrator of the Environmental Protection Agency, who was sworn into office in July, added, "I'll be talking about cahs later too, which is c-a-r."
McCarthy's self-deprecating humor is a new asset in the Obama administration's push to sell its climate plan - in Friday's case, regulations that will use the Clean Air Act to severely limit greenhouse gas emissions from yet-to-be-built power plants.
She also emphasized, for the second time this week, that the climate policies do not add up to a "war on coal," a persistent charge from many Republican lawmakers, Democrats from energy-producing states and many in the fossil fuels industry.
"Cutting climate change just makes good business sense," McCarthy said, adding that "setting fair Clean Air Act standards does not cause the sky to fall."
Beyond the business case, McCarthy cited links between a changing, warming climate and risks to public health and safety from smoggy air, with lower income and urban communities particularly at risk.
McCarthy became emotional at times when she discussed the health problems caused by smog, such as the life-threatening Chronic Obstructive Pulmonary Disease (COPD) that afflicts Daniel Dolan-Laughlin, a retired railroad executive from Wheaton, Illinois.
"Daniel's health has improved significantly after he received a double lung transplant," she said. "Last year Daniel came to EPA to tell his story. He made a specific plea: he asked us to act on climate change."
McCarthy's down-to-earth communications style has been on display for three days in Washington as part of a very public rollout of the carbon-cutting regulations.
On Wednesday, she faced pointed questions from Republicans on the House of Representatives Committee on Energy and Commerce at a hearing to examine current and future regulations which it said cost $22 billion this year.
At that hearing, McCarthy parried questions about whether the proposed regulations would be so tough that they would effectively prevent new power plant construction.
McCarthy sat for interviews with publications ranging from the mainstream - the Washington Post - to the partisan - Grist, an environmental news and commentary website. Her speech to the National Press Club was carried live on C-SPAN.
McCarthy's path to this spotlight has been a bumpy one.
Confirmed after more than four months of partisan wrangling, she came to the job after overseeing rules on mercury and soot pollution as EPA's top air official.
Before coming to the federal agency, McCarthy earned bipartisan stripes as the top environmental regulator in Massachusetts and Connecticut under Democratic and Republican governors.
She was the environmental policy adviser to then-Massachusetts Governor Mitt Romney, the 2012 Republican presidential nominee. (Editing by Ros Krasny and Jim Loney)