Coal-fired power plants like this one in Thompsons, Texas, emit soot and other pollutants when coal is burned to make electricity.
In another case of environmental rules becoming election fodder, the Obama administration on Friday proposed tighter restrictions on soot, a pollutant caused mainly by smokestacks and diesel engines.
It had been called "the sleeping giant of clean-air issues" by Frank O'Donnell, head of the activist group Clean Air Watch. And while little was made of it until now, Republicans and industry were quick to pounce on it as more red tape in a weak economy.
The proposed Environmental Protection Agency rule would set the maximum allowable standard for soot in a range of 12 to 13 micrograms per cubic meter of air. The current annual standard, last revised in 1997, is 15 micrograms per cubic meter.
The EPA had delayed its required review of the Clean Air Act's soot provision, leading New York, California and nine other states to sue. Under a court order, the EPA agreed to unveil its proposal this week.
O'Donnell was not impressed with EPA's pace. "EPA had to be dragged kicking and screaming to do this," O'Donnell told msnbc.com, referring to the lawsuit. The states, along with activists and the American Lung Association, argued that tougher standards will reduce premature deaths and asthma attacks.
"Clean air is not a luxury," New York Attorney General Eric Schneiderman said after a court ordered the EPA to act. "It is a basic public right, and standards that protect it are an absolute necessity."
The proposal follows the World Health Organization's declaration on Tuesday that diesel fumes can cause cancer.
The risk is small, a WHO science panel noted, but raising the status to carcinogen from "probable carcinogen" was an important shift because so many people breathe in the fumes in some way.
"It's on the same order of magnitude" as secondhand smoke, said Kurt Straif, director of the WHO department that evaluates cancer risks. "This could be another big push for countries to clean up exhaust from diesel engines."
That finding, O'Donnell argued, "is all the more reason EPA needs to get tough on particle soot."
Republicans, for their part, in recent months have seized as election fodder the argument that environmental regulations are strangling economic recovery.
House Energy Committee Chairman Fred Upton, R-Mich., reiterated that in a letter to EPA chief Lisa Jackson last week, saying that "stringent standards" on soot "will likely be costly and have significant regulatory and other implications."
The American Petroleum Institute agreed. "By continuing to implement the existing standards we would avoid the potentially heavy added economic costs of more stringent standards, which our economy and American workers cannot afford," spokesman Howard Feldman told reporters Tuesday.
The EPA countered that soot pollution has already been reduced since the last rule revision in 1997 and that the proposed standard is more of a formality.
All but six counties across the country would meet the proposed standard by 2020 with no additional actions needed beyond compliance with existing and pending rules, the EPA said.
Those counties are San Bernardino and Riverside counties in California; Santa Cruz County, Arizona; Wayne County, Mich.; Jefferson County, Ala. and Lincoln County, Mont. All six face "unique challenges" and will receive individual attention, the EPA added.
Still, Bill Becker, head of the National Association of Clean Air Agencies, told msnbc.com that "meeting the standards could be far more challenging" for some counties than others, and he urged the EPA and Congress to provide resources to enforce any new standard.
As for enforcing a new rule, Becker noted that "today’s proposal is an ‘ambient’ standard, not an emission limit on industry." Any state with a county consistently above the standard would be required to draft a strategy to curb emissions, he added, and that could then "trigger additional controls on industry."
After a public comment period, a final rule is expected in December.
The Associated Press contributed to this report.
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