Run your hand across a window sill in Curtis Bay, and you’re likely to come up with a dark film coating your fingers.

For decades, residents of the industrialized South Baltimore neighborhood have said this dust is coal that wafts off the property from CSX piers next door, where millions of tons of coal pass through each year. Residents have said this dust is harming them; some describe routinely hosing down their homes and report stories of respiratory problems and childhood asthma.

About six months ago, Maryland environmental regulators released a report that confirmed what Curtis Bay residents had said all along: there’s coal dust throughout their neighborhood.

But one key party, the company whose trains deliver the coal into Curtis Bay from Appalachia, isn’t convinced.

Last month, CSX Transportation released a 121-page response to the coal dust report — a collaboration between researchers at the Johns Hopkins University and the University of Maryland, citizen scientists and the Maryland Department of the Environment — attempting to dismantle its findings, writing that researchers “relied on flawed approaches to draw unfounded conclusions.”

CSX argues that many of the methods deployed by the community’s researchers, including low-cost air quality monitors, tape strips and statistical models, were flawed. Experts hired by the Jacksonville, Florida-based company argue that the community report dubiously assumes that certain dust compounds found in the neighborhood were coal from their terminal, despite the presence of dozens of other industrial polluters in South Baltimore.

The question of coal dust’s consequences for the neighborhood “may warrant further study,” argued Raghu Chatrathi, CSX’s senior director of public safety, health and the environment, in a cover letter to the analysis, but the state-backed report doesn’t provide evidence to prove that dust from the CSX site has had a significant impact on the neighborhood’s air quality.

The lengthy rebuttal comes as state environmental regulators are preparing to release a new, five-year operating permit for the CSX coal piers, its first since an explosion at the site rocked Curtis Bay in late 2021. CSX says in their response, assembled by third-party scientists and consultants, that any regulatory decision based on this report would be “arbitrary and capricious, and not in compliance with Maryland law” — potentially laying groundwork for a lawsuit if the state comes out with a restrictive environmental permit.

At the same time, coal exports at the Port of Baltimore are booming. Between CSX and a separate terminal across the water, coal exports through the port surged to a historic peak last year — ballooning to nearly eight times the export volumes of two decades ago, driven largely by growing demand in India and other parts of Asia.

Advocates and community members in Curtis Bay have called on regulators to shut down the CSX terminal. Though the state environmental department has argued that such a step would go beyond its authority, regulators extended their permitting process in part so they could take the findings of the collaborative coal dust report into account in their permit decision. Secretary of the Environment Serena McIlwain said at the time the research would “lead the way” in the state’s permitting process, while her department called the report “the most advanced community-led air quality monitoring project ever undertaken in Maryland.”

Short of denying CSX its permit, the state regulators could mandate stricter protections against coal dust or even force the company to enclose its open-air terminal.

In an email, Maryland Department of the Environment spokesperson Jay Apperson said regulators are reviewing “all testimony, comments, data and science” as part of the record. “As with any permit application, our priority and goal is to protect the environment and public health.”

The coal piers are just across the street from homes, bars, a neighborhood rec center and playground, and barely a quarter-mile from Curtis Bay Elementary School.

Over three rounds of testing last fall, researchers found coal dust in 100% of samples taken across eight different sites in Curtis Bay, ranging from adjacent to the CSX terminal to three-quarters of a mile away. Air monitors detected coal dust drifting over the CSX fence line close to once every 1 1/2 hours, while incidents of high intensity coal dust proliferation spanned an average of six minutes, with the longest lasting for 137 minutes.

Russell Dickerson, a professor in the Department of Atmospheric and Oceanic Science at the University of Maryland who assisted in the collaborative report, said the CSX rebuttal attempts to muddy the waters by arguing that researchers failed to prove the harms of coal dust to the neighborhood.

In reality, researchers set out to answer a “yes” or “no” question, Dickerson said: Is any coal dust from the CSX pier getting into the community? The answer, unequivocally, is yes, said Dickerson, who said researchers found mixtures of all sorts of particles, including dust from other minerals, bits of metal, organic matter and “absolutely, coal dust.”

“There definitely is coal dust there,” he said. “It is minimally a nuisance and possibly a health hazard.”

CSX has argued that it is already taking necessary steps to address pollution, including through spraying its coal piles with water and installing a fence-line monitoring system.

Among other things, the company’s rebuttal alleges that researchers did not adequately account for the heavy presence of diesel truck traffic in the industrialized neighborhood, which the third-party scientists argue is a key contributor to black soot found around the neighborhood. In one instance, the state-sponsored report presents photo evidence of a dark plume hovering over a CSX coal pile, which CSX says is in fact exhaust from a nearby ship — not coal dust.

At the same time, the community report relied on a problematic statistical model as well as unreliable and inconsistent air monitoring methods, the rebuttal states.

A “major flaw” of the collaborative report, CSX’s experts argue, is researchers’ focus on an indicator of coal dust — a particle compound referred to throughout the community report as “putative coal dust” — may in fact come from other sources.

Dickerson quipped that “lawyers and scientists have very different approaches to discovering the truth” and said the substance he reviewed could only have been coal dust.

Researchers are working on a scientific response to the CSX rebuttal, and Dickerson said there’s more work still to be done to determine just how much of the dark soot on Curtis Bay homes is coal. But he said that judging from the samples he studied, much of the compound he viewed under the microscope was coal — maybe even most of it.

In a statement, the Community of Curtis Bay Association, also a partner in last year’s coal dust report, said the community is not surprised that the rail giant “paid consultants to cast doubt on the truth: that CSX moves a large volume of coal through our neighborhood, and coal dust trespasses onto our homes, schools, and churches daily.”

The association reiterated demands for state officials to end coal exports from their neighborhood and enclose the open-air terminal to prevent dust from escaping into the community, and also pointed to CSX’s recent, $1.75 million settlement with Curtis Bay residents over the 2021 explosion. Though CSX admitted no fault in the court agreement, the community association said the settlement was reached “in light of the plain truth of the matter” and “to address the harm they caused.”

The CSX rebuttal lays out many factually correct points that distract from the community and researcher’s central finding, said Dickerson. For instance, the CSX response notes that small particulates found in the neighborhood fall within federal environmental air quality requirements.

While true, Dickerson said, “that doesn’t mean that there’s no problem.”