In its latest set of Clean Air Act rules, final regulations for levels of fine and coarse airborne particles, the Environmental Protection Agency has moved to tighten one standard, revoke another and leave two unchanged. EPA's actions, announced Sept. 21, drew criticism from industry groups, which say the agency was too strict. They also sparked blasts from environmental groups, which contend the agency wasn't tough enough.

In its new rules, EPA cut the daily standard for fine-particle pollution, or PM 2.5, to 35 micrograms per cubic meter, from 65 micrograms now. But EPA retained the current PM 2.5 standard of 15 micrograms.

EPA says the number of counties that fail to meet the new daily fine-particle benchmark will rise, compared with the total in "nonattainment" with the current standard. EPA projects that 32 counties won't meet the new fine particle level in 2015. At present, two broad areas of California don't meet the 65 microgram mark.

Industry officials say 530 counties won't meet the annual fine-particle standard, up from 208 now. But EPA spokesman John Millett says as other regulations take hold, such as the diesel fuel and clean air interstate rules, the 208-county number will "certainly drop quite a bit by 2015" .

Joe Stanko, counsel for the Electric Reliability Coordinating Council, an electric-utility group, says being in "non-attainment" with the particulates rule "makes it significantly harder for communities to attract new businesses, expand existing plants or make infrastructure improvements."

Nonattainment counties' plans won't be in "conformity" with clean air requirements and may have federal highway aid withheld, says Nick Goldstein, American Road & Transportation Builders Association staff attorney. Jeopardizing congestion-easing projects is "self-defeating when it comes to air quality," he says.

For coarse, inhalable particles, or PM 10, EPA kept the 24-hour limit at 150 micrograms. It revoked the annual standard of 50 micrograms, saying "available evidence" doesn't suggest a link between long-term exposure to current particle levels and health problems. National Stone, Sand & Gravel Association President Joy Wilson calls EPA's decision "good news for aggregate producers nationwide."

Environmental groups don't like EPA's rules. "The administration has chosen to ignore its own scientific and medical advisers and expose thousands of people to higher risks of disease and other ailments," says National Environmental Trust President Philip Clapp.

Barring court challenges, the rules take effect 60 days after they appear in the Federal Register. States will have until April 2015 to comply. EPA officials say that the deadline could be extended by five years.