WASHINGTON (AP) — The issue may be dust in the wind, but Republicans are still moving to block it.

Environmental Protection Agency officials have said — over and over again — that they won't propose new regulations to limit dust kicked up by farm equipment. But anti-regulation sentiment is strong this year on the campaign trail, and real or not, House Republicans are planning to vote this week to prevent such regulations.

Republicans and even some Democrats have told farm-state audiences that the EPA is considering a crackdown on farms, despite the agency's public statement in October calling that a "myth."

Supporters say they are pushing the bill this week because they want more certainty for the agriculture industry. The House GOP has pushed a host of measures aimed at weakening, delaying or scrapping environmental regulations in recent months, saying they view them as job killers.

South Dakota Rep. Kristi Noem, the bill's sponsor, says the EPA's assertions don't "hold a lot of water" for wary farmers.

"The EPA has been so aggressive on a lot of its policies, so we just want to make sure they can't take any action that can hurt the farm industry right now," she said.

Democrats have scoffed at the bill and are calling it a waste of time.

Maryland Rep. Steny Hoyer, the No. 2 Democrat in the House, joked sarcastically on Tuesday that the bill is "critically important" since the EPA has said it has no intention of regulating farm dust.

"We are once again doing a bill that is not necessary and has no effect," Hoyer said at a news conference at the Capitol.

In letters to two senators in October, EPA Administrator Lisa Jackson said the agency won't expand its current air quality standards to include dust created by agriculture. "We hope this action finally puts to rest the misinformation regarding dust regulation and eases the minds of farmers and ranchers across the country," Johnson said then.

That didn't stop the opponents' message machine. Just a few weeks later, Republican presidential candidate Herman Cain, who has since suspended his campaign, ran a television ad in Iowa that quoted a farmer saying, "The EPA wants to regulate dust."

Though Republicans often blame the Democratic Obama administration for an overly aggressive EPA, the Republican Bush administration also had a hand in the matter. The Bush EPA proposed regulating rural and urban areas when it comes to "coarse particulate matter" — or soot — in the air, meaning farms could fall under tighter restrictions. Farm groups challenged that in court, and a federal appeals court ruled in February 2009 that the EPA had already provided the evidence necessary to determine farm dust "likely is not safe."

Obama's EPA initially defended that decision. An EPA spokeswoman said after the ruling that regardless of whether someone lives in a rural or urban area, the threshold for unsafe levels of dust in the air should remain consistent nationally. But later, Jackson said the agency was unlikely to single out farm dust.

Under current rules, states are tasked with making sure that their levels of particulate matter in the air are below certain levels. Farm groups worried, however, that their pollution — dust kicked up behind a combine, for example — would be targeted separately or would be vulnerable to additional lawsuits.

Environmentalists say the House bill, which is not likely to make it through the Senate, would prevent the EPA from even considering tighter regulations if that became necessary for public health.

"When it comes to stuff in the air that could harm your health, it would be nice if the government could at least do an honest assessment," says Frank O'Donnell, president of Clean Air Watch. He says the bill is "totally detached from reality — the kind of issue that makes people cynical about Congress."