The Environmental Protection Agency wants to treat the different ethanol producing plants the same when it comes to air pollution.

Corn milling facilities that make ethanol for human consumption can emit up to 250 tons of emissions a year before clean air regulations that restrict production kick in. The threshold for plants that make ethanol for fuel is much lower, at 100 tons a year.

The difference between ethanol for fuel and ethanol for human consumption is that a small amount of gasoline or solvent is added to the fuel ethanol to make it undrinkable and the process does not use food-grade equipment.

"EPA's proposal would provide equal treatment for corn milling facilities, regardless of whether they produce ethanol for fuel or human consumption," the agency said.

Republican Sen. John Thune of South Dakota had asked the EPA for the policy change. He said the agency's proposal "seeks to remove stifling regulatory barriers so ethanol production can increase and we can make significant progress toward our goal of achieving energy independence in the US"

The EPA's proposal, which would be open for public comment for 60 days, comes as US oil refineries are scrambling to secure ethanol supplies for blending into gasoline.

Refiners will need more ethanol this year to mix with their gasoline as they stop using the fuel additive MTBE, which has been banned by many states and resulted in lawsuits for polluting drinking water supplies.

However, the Energy Department says domestic ethanol producers will not make enough of the product to meet demand for most of this year, and more ethanol imports, particularly from Brazil, will be needed to close the supply gap.

The current transition to ethanol caught some oil companies that were planning to eliminate MTBE at a later date off-guard.