"It is not really about farms at all," he said. "It's real effect is to exempt industrial mining operations and other large industries from regulation under the Clean Air Act, and it threatens to overturn the particulate pollution standards that protect families in both rural and urban communities."

Waxman said the bill, H.R. 1633, would ban regulations related to "nuisance dust," but defines "nuisance dust" in a way that could exempt not just farmers, but coal mining operations and cement plants from new particulate-matter rules. He also said Republicans rejected amendments aimed at ensuring that the bill only blocks potential new rules on dust related to farms.

Under the bill, nuisance dust is defined as particulate matter that is "generated primarily from natural sources, unpaved roads, agricultural activities, earth moving, or other activities typically conducted in rural areas."

RepublicansĀ said dozens of agricultural organizations support the bill andĀ it is needed because the Environmental Protection Agency has threatened to set new rules that would regulate farm dust.

"Listen to the American Farm Bureau Federation and all its state affiliates," Energy & Commerce Chairman Fred Upton (R-Mich.) said. "Listen to the National Cattlemen's Beef Association and over 185 other organizations who collectively represent a significant portion of the rural economy. These organizations believe that this bill is necessary, and so do I."

Once general debate ends, the House was expected to consider up to eight amendments before approving the bill.