Maryland environmental regulators imposed new restrictions Tuesday on the operations of a massive coal export terminal in South Baltimore, requiring its operator to erect a giant screen to keep dust from polluting the air of nearby neighborhoods.

CSX Transportation, the rail giant that operates the Curtis Bay terminal, has faced protests for years over the dark dust that often coats homes of nearby residents. Community members and environmental advocates have called on state regulators to deny the company a new permit and shut its facility down.

Maryland Department of the Environment officials, though, insist such steps are beyond its authority.

The new permit, which MDE described as among the most stringent in state history, requires CSX to surround its rail terminal with a “windscreen” higher than its coal piles to minimize dust blown offsite. The windscreen requirement differs from a draft version of the permit released nearly a year ago, in which MDE described required enclosures as a “physical barrier.”

“We are holding CSX to a higher standard by requiring an enclosure to control dust — a critical step to protect the health of the surrounding community,” Secretary of the Environment Serena McIlwain said in a statement. “This is the most protective permit ever issued for this site, reflecting our commitment to environmental justice.”

In a statement Monday evening, a CSX spokesperson said the company is reviewing the new permit and will have more to say at a later date.

The Jacksonville, Florida-based rail giant previously pushed back on claims it’s to blame for the dark dust coating Curtis Bay, a working-class neighborhood surrounding by other industrial sites.

The new permit is a long-time coming: CSX’s last permit was supposed to expire in September 2023, and this new license is the first for the coal piers since an explosion there rocked the surrounding Curtis Bay neighborhood in late 2021, blanketing much of the area with dust.

That incident helped galvanize opposition to the coal piers, and MDE extended its public feedback process in part to incorporate research, led by local university researchers and community members, into the extent of coal dust pollution in the neighborhood.

Other factors, such as the collapse of the Francis Scott Key Bridge in March 2024, further delayed the final permit.

The CSX terminal and a separate coal pier across the Patapsco River near Canton combine to make Baltimore the country’s second-largest exporter of coal. In recent years, exports of Appalachian black rock through Baltimore have boomed, with most of the coal traveling overseas to India.

The state’s final permit stops short of requiring CSX to enclose its terminal from above, as is the case with some storage facilities in other parts of the country. It in many ways resembles a draft version released last year, which community members and advocates criticized as insufficient for stopping dust pollution.

Last week, Johns Hopkins University researchers released new findings on the frequency of coal dust pollution from the CSX facility. Their study links high instances of dust pollution to times when the wind is blowing across the terminal, or when bulldozers are active on the site.

CSX already has a shorter windscreen set up at the property’s southern edge — one of the locations monitored by researchers in the latest Johns Hopkins report.

Even beyond the existing windscreen, researchers detected similar levels of coal dust escaping: “This suggests that off-site community air pollution burden is not reduced by wind screen netting mitigation strategies,” the report concluded.

Carlos Sanchez, an organizer with the South Baltimore Community Land Trust and co-author on the Johns Hopkins paper, said Monday night that this research makes it clear that the use of wind screens and water sprayers at the coal terminal isn’t enough. He criticized the permit for not setting specific limits on the amount of dust that can enter the community.

“No amount of coal dust is acceptable,” Sanchez said. “The State of Maryland should not ask any community to treat toxic pollution as a fact of life — yet that’s exactly what’s happening here.”

CSX, though, argued in lengthy comments to MDE, released Tuesday by the agency, that the “physical barrier” required under the draft permit was too burdensome.

To meet the requirement, CSX said it would have to either dramatically scale back volumes, an illegal infringement on railroad operations, or build barriers over 110 feet tall — “an engineering feat never before required or achieved” at a North American coal terminal, the company said.

In response to comments, MDE estimated that fully covering the terminal with a dome would cost around $50 million and said it opted for windscreens as a more affordable measure that wouldn’t significantly impede CSX operations.

According to the agency, the windscreen requirement isn’t designed to block or filter the coal dust itself, since those particles can be very fine. Instead, the screen would function as a kind of curtain to block wind from carrying coal off the CSX property.

CSX has 120 days to submit plans for the barrier to MDE, and 18 months after that to erect its screen.

In addition to the windscreen, the new permit requires CSX to replace existing water sprayers in its railcar unloading sheds with an automated system meant to more efficiently control dust.

The company has hinted before about the possibility of legally challenging a restrictive permit.

In its comments to regulators, CSX reiterated concerns about the state-backed community study on coal dust pollution, arguing that any regulatory decision based on those findings wouldn’t comply with Maryland law.