Farms frequently produce dust clouds during harvests, and farmers are waiting nervously to hear whether the U.S. Environmental Protection Agency plans to clamp down on dust and dirt.
The American Lung Association and others have called for tougher dust controls when the EPA revises air pollution standards.
But members of Congress from rural areas have asked the EPA not to tighten rural limits on the so-called coarse particulate matter. Tighter controls could require farmers to pave more gravel roads or use costlier no-till farming practices.
Vilsack tried to ease the worries of farmers.
"I don't think that farmers should presuppose that there's going to be a significant amount of regulation" about farm dust, Vilsack told reporters after he spoke to the Denver Metro Chamber of Commerce.
Vilsack said he was confident the revised air-quality standards won't burden farmers.
"I'm reasonably certain that the EPA understands - by virtue of my conversations with Lisa Jackson, the administrator - that they have to make them reasonable," Vilsack said.
A farming group that sued over farm dust rules five years ago reacted cautiously to Vilsack's assurances.
"We've learned not to take anything for granted from any agency and not to believe what any agency says until it happens," said Richard Krause, senior director of congressional affairs for the Washington-based American Farm Bureau Federation.
The group sued the EPA in 2006 during its previous review of airborne pollutant standards. The lawsuit was unsuccessful, but the environmental agency ended up not changing rural standards.
Krause hopes the agency makes the same decision this time. Draft rules are expected later this year.
"We want to make sure they understand the concerns of rural America," Krause said.
Vilsack told the business group that the nation would set a record this year with $136 billion in agricultural exports. He also repeated his plea for Congress to ratify a free trade agreement with South Korea to boost exports by an additional $1.8 billion a year.
Members of Congress have indicated they would hold off on the South Korea agreement until they see similar accords with Colombia and Panama.