"The U.S. Environmental Protection Agency said on Monday it will not tighten controls on dust particles on farms when it sends the rule to the White House for its regular five-year review. Some Republicans, including presidential hopeful Herman Cain, have said the EPA would expand the rule, which mainly affects heavy industry and vehicles, and regulate farms more broadly. The agency sent a letter late last week to Senate Agriculture Committee Chairwoman Debbie Stabenow and fellow farm-state Democrat Amy Klobuchar saying it will keep soot standards in place, but not tighten the rules to regulate larger particulates. Critics have used the potential of farm-dust regulation as a headline issue in complaining of runaway regulation. Nebraska Sen Mike Johanns, a Republican, said he has 26 co-sponsors for a bill to bar regulation of dust from farm fields and dirt roads. An EPA spokeswoman said the letter should end the "myth" of broader farm-dust regulation. Concern arose from proposals during the review process for stricter rules..."Based on my consideration of the scientific record, analysis provided by EPA scientists and advice from the Clean Air Science Advisory Council, I am prepared to propose the retention -- with no revision -- of the current PM10 standard and form when it is sent to the (White House) for interagency review," wrote EPA administrator Lisa Jackson in the letter to the senators."