The burning starts in October, when sugarcane companies begin to set fire to nearly 400,000 acres on the shores of Florida’s Lake Okeechobee, clearing away the leaves to prepare the plants for harvest. When the flames die down, machines roll in to chop down the stalks and shunt them off to nearby mills for processing.

For the people who live nearby, the burning means something else. Every year, for eight months, bursts of thick smoke billow from the fields into the air, causing an ash the locals call “black snow” to drift down from the sky. The particles coat their homes, their cars, and their clothes. They’re ingested by children, who develop higher rates of asthma, and by expectant mothers, who are more likely to lose the pregnancy.

That’s according to two residents, Clover Coffie and Jennie Thompson, who on Tuesday filed a federal class-action lawsuit in the Southern District of Florida. The plaintiffs are seeking damages from the negative health effects of burning sugar cane fields, a practice that the South Florida Sun-Sentinel reports has been going on for decades.

“They would be monitoring the health of the residents there who have been exposed to pollutants from sugar cane burning in order to identify and begin to treat any health conditions that are created in that population as a result of the sugar cane burning,” said Zach West, an attorney who filed the suit, at a press conference. “We’re also seeking full reimbursement for the depression of property values in that area related to the sugar cane burning. The costs of such a program are going to be enormous.”

The Sun Sentinel reports West was joined by former Florida state senator Joe Abruzzo and Frank Biden, brother of Joe, both of whom work for the Berman Law Group. Standing with them was Fred Taylor, a former NFL running back who grew up breathing black snow in Belle Glade, Florida, where the town motto is “her soil is her fortune.”

A tall, perennial grass that resembles bamboo, sugarcane is an essential source of the refined sugar we eat in America. The plant accounts for 40 percent of all sweeteners consumed, according to Jack Roney, the director of policy for the American Sugar Alliance. Corn syrup and beet sugar account for the rest.

The crop thrives in tropical climates; in America, it is grown in the Louisiana Delta and the lower Rio Grande Valley in Texas. The primary growing state is Florida, however, where the sugarcane industry took off after the U.S. stopped imports from Cuba in 1960, according to USDA’s Economic Research Service. Today, the Sunshine State is responsible for up to 17 million tons of sugarcane harvest every year, grown principally in the acreage along the southern and southeastern shores of Lake Okeechobee. Palm Beach, where the plaintiffs live, is by far its most productive county. Yet the fields are “so compact that most Florida visitors never even see a sugarcane field,” the state Farm Bureau gloats.

And this is where the burning comes in. During the growing season, from October to April, growers set their fields aflame to rid the plants of leaves and vegetation, leaving “nothing standing but the cane,” as an environmental engineer puts it. That’s partly a matter of harvesting efficiency, but also, burning can evaporate the water in the stalks, which bumps up their sugar content, the lawsuit alleges.

The sugar industry, for its part, says that burning off all that sugar-free biomass isn’t just about getting the most out of the yield, or harvesting more efficiently. Other alternatives, like mulching the leaves, are “just not feasible,” the president of the Sugar Cane Growers Cooperative told the Sun-Sentinel, because leaving them on the ground would smother the next crop growing in the muck. That’s disputed by environmentalists like the Sierra Club, who allege that sugarcane growers in Australia and Brazil have been able harvest without burning, and that there are other uses for the leaves (e.g., creating biofuels).

Clearly, the practice is controversial: Michael Grisham, who leads sugarcane research for the USDA’s Agricultural Research Service, refused to comment to The New Food Economy on the efficacy of pre-harvest burning, saying that while there could be agricultural benefits like higher yields, growers were nevertheless “sensitive” to related health issues. Like, for example, the kidney damage that sugarcane field workers suffer, and respiratory issues suffered by people who come into contact with the smoke. Arturo Rojas, a chemical and environmental engineer, cautioned residents in San Antonio to stay inside during the “May Murkies,” or the annual haze caused by burning sugarcane fields, drifting up from Mexico.

In the complaint, the plaintiffs also allege that the “black snow” from the fires discolors cars, homes, and office buildings, which incurs cleanup costs and tanks property values.

Other effects are more lethal. During the harvest season, the plaintiffs allege, residents breath air concentrated with toxic particles, at a rate that’s 15 times higher than it is in the summer. As a result, mothers fret about “putting their kids to bed at night” while the cane is burning, according to a video the attorneys released. One mother, who has lived in Belle Glade for 23 years, said her four-month-old son has already been diagnosed with asthma. All told, Abruzzo said, there were nearly 700 asthma-related hospitalizations for every 100,000 residents in Palm Beach County, which the Sun Sentinel says is almost five times the state average.

What’s particularly galling, according to Abruzzo, is that this is disproportionately affecting poor people. He says he wasn’t aware of the issue until 2017, when the wind shifted and blew ashes into Boca Raton, causing an uproar among “politically active retirees,” as the Sun-Sentinel put it. Generally, he says, the sugar companies will only burn the fields when the wind blows west, which disperses the ash onto the poorer communities of Belle Glade, Pahokee, and South Bay.

As the Tampa Bay Times reports, those residents of the western Everglades are mostly low-income blacks and foreign laborers. At a church meeting held a year ago, attendees explained what life was like for them. The pastor, for instance, says he took his “heavy breathing and allergy flare-ups for granted,” until he went to college in Michigan, and it disappeared. Today, his son uses some kind of a “breathing machine” during the burn season. A teacher said when her students were outside, they wore garbage bags over their heads so they wouldn’t inhale ash (perhaps not a best practice).

While none of the defendants we contacted offered comment, a spokesperson for U.S. Sugar told the Sun-Sentinel that its “farming practices are safe, environmentally sound, highly regulated and closely monitored.” Florida Crystals, meanwhile, told local station WPBF that its burns are “regulated and permitted” by the Florida Forest Service.

The plaintiffs have demanded a jury trial, and as of press time, the companies have not responded to their complaint.