A new legal fight aims to stop the harvest season burning of South Florida sugar cane fields, which can send smoke and ash billowing all the way to the coast.

Environmental groups Thursday filed a legal challenge asking the U.S. Environmental Protection Agency to overrule the state and start regulating the burning, now allowed on 400,000 acres of sugar cane fields in the farming region that stretches south of Lake Okeechobee.

The Sierra Club and Earthjustice argue that the burning pollutes the air and worsens everything from allergies to asthma.

“People living in these communities have to breathe hazardous, black smoke. There’s a foul odor in the air and ash raining down. It’s not right, and that’s why we are challenging the [state] permit,” said Frank Jackalone, of the Sierra Club.

Yet state health officials have maintained that sugar cane field burning doesn’t violate air pollution limits.

And sugar industry representatives defend the practice of burning the grassy fields as an efficient, safe way to expose the sugar-packed stalks sought during harvest.

The environmental groups’ arguments “already lost at the state level, [and] they are now attempting to shop the same discredited arguments with federal regulators,” U.S. Sugar spokeswoman Judy Sanchez said. “These petitions are motivated by a desire to inflict economic harm on our business, our farmers’ way of life, and our communities. We look forward to seeing this baseless petition dismissed.”

South Florida’s sugar cane harvest lasts from October to April and this year it’s expected to produce nearly 17 million tons of sugar cane, to be turned into more than 2 million tons of sugar.

Growers have long used controlled burns — often about 40 acres at a time — to get rid of the sugar-less, leafy portions of sugar cane surrounding the stalk. After the fast-burning fires die down, harvesting machines chop and gather the stalks that are taken to a sugar mill.

The Sierra Club and Earthjustice want federal regulators to veto the state permit for U.S. Sugar Corp.’s sugar mill in Clewiston.

The environmental groups maintain that the state permit that governs emissions from the mill fails to factor in the smoke from burning sugar cane fields, many of them in Palm Beach County.

The months of burning thousands of acres of land should be declared a “hazardous air pollutant” and linked to the mill’s emissions, according to the legal challenge.

“Burning sugar cane fields is an outdated practice that should be stopped. People living in South Florida have the right to breathe clean air, and allowing this company to conduct open burning on thousands of acres without Clean Air Act regulation is both unfair and unsafe,” Jackalone said in a statement released Thursday.

The Sierra Club and Earthjustice argue that some sugar producers in other countries, including Australia and Brazil, have stopped burning their fields. They say that instead of burning, the leafy portions of sugar cane plants could be cut and used for mulching the fields or taken and burned elsewhere as biofuel.