DTE Energy witness defends Detroit’s air quality in Zug Island trial testimony

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A toxicologist challenged a Harvard epidemiologist’s conclusions about Zug Island pollution during Wednesday federal court testimony.

Kathryn Kelly, president of Delta Toxicology, was called as a defense witness in the bench trial of the Environmental Protection Agency’s Clean Air Act lawsuit against EES Coke Battery and DTE Energy. 

Joel Schwartz — a professor at the Harvard T.H. Chan School of Public Health who testified for the government Sept. 18 that pollution from EES Coke Battery causes premature deaths — is incorrect, Kelly said.

Schwartz used methodology inconsistent with best practices, made misleading conclusions about exposure to sulfur dioxide and PM 2.5, and miscalculated the social costs of EES Coke Battery’s pollution, Kelly said.

Kelly calculates those social costs at $5.95 per ton, rather than the figure of $66 per ton of excess sulfur dioxide emitted that Schwartz gave. 

The toxicology expert said Schwartz did not make a site visit to the coke battery or surrounding areas, and did not use local air monitoring data in his analysis. Kelly visited the facility and Windsor on May 7, 2024 to look for “evidence of effect,” she said. 

“I didn’t smell anything in Windsor. Around the facility, I saw people fishing, riding bikes,” Kelly said.

Detroit’s air quality is very good: Defense witness

U.S. attorney Samantha Ricci showed Kelly key findings from the American Lung Association’s 2025 State of the Air Report during cross-examination. 

Detroit ranks sixth worst for annual particulate matter pollution in the report, with over 12 micrograms per cubic meter of particulate matter on an annual basis.

The EPA set the health-based annual PM 2.5 standard at 9 micrograms per cubic meter last year. 

Kelly said she does not know what nonattainment means or how it relates to the National Ambient Air Quality Standards. Kelly is not an epidemiologist or expert on pollution controls, she said: she’s a toxicologist who integrates epidemiology, biostatistics, and “many pieces of the puzzle” to get a full picture.

Ricci showed the court the transcript of a deposition Kelly gave in which she was asked whether the lung association — a nonprofit, public health organization established in 1904 — is a credible source. Kelly said no.

The lung association lobbies on behalf of the EPA, Kelly said in court Wednesday.

“I’m (a) data girl, when it comes to policy I’m the person that takes a closer look at what they don’t want us to look at. Policy is not relevant to toxicology,” she said. 

When asked by Ricci whether she believes air quality in Detroit is “very good,” Kelly said it is, and the country has “done a great job” in reducing criteria air pollutants, which are regulated by the EPA under the Clean Air Act. 

The EPA’s website says air quality based on concentration of criteria pollutants has improved since 1980, though around 140 million people nationwide live in counties with pollution levels above National Ambient Air Quality Standards.

Rhiana Dornbos, vice president and director of project management excellence at NTH Consultants, testified for the defense Wednesday on EES Coke Battery’s good faith compliance with permits and regulations. 

From 2018 to 2019, Dornbos said she was not aware that EES Coke’s sulfur dioxide emissions surpassed the levels stated in the facility’s 2014 permit. 

In 2021, U.S. Steel, also located on Zug Island, announced its facility was being idled, and that’s when Dornbos noticed a change in emissions occurred, she said. 

DTE is one of NTH Consultants’ top clients, Dornbos  said. 

Julie Brunner, engineer manager of renewable operating permits at the Michigan Department of Environment, Great Lakes, and Energy, was also called to testify by the defense Wednesday. 

Brunner said she reviewed permits for EES Coke Battery in 2012 and 2013, including a temporary permit for a minor source action.

When asked during cross-examination by Ricci whether EES Coke Battery told EGLE of an increase in emissions, and whether the company came to EGLE to seek a major modification permit, Brunner said no.

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