A week after one of Pittsburgh’s most polluting steel plants closed in 2016, cardiovascular ER visits in the nearby communities dropped by 42 percent and continued to shrink every week for years, according to a recent study published in the journal Environmental Research Health. Cardiovascular and cerebrovascular hospitalizations also decreased.

While most research on air pollution makes associations between certain pollutants and health effects, there is little research on the specific health benefits of particular plants closing. But the New York University  study attempts to do just that. 

“It’s exciting to see something like this, especially as we are undergoing a huge energy transition in this country and in the world,” said Joan Casey, an environmental epidemiologist at the University of Washington who did not participate in the study. “How we characterize these co-benefits of the energy transition and how we calculate the huge potential health benefits is really important.” 

Researchers from NYU Langone Health looked at the closure of Shenango Inc., a steel coke plant in Pittsburgh, to assess the health benefits for nearby residents. A typical epidemiological study looks at two data sets—air pollution and health data—and then uses statistical methods to show the connection, said Lucas Henneman, an environmental engineer and assistant professor at George Mason University in Virginia whose research focuses on pollution and health and was not involved with the study. “But what makes this stand out is that they are looking at this very specific intervention.” 

Researchers compared the area exposed to the plant’s pollution, an area exposed to pollution from another plant and a third area without any exposure. Then they analyzed five years of air pollution and healthcare data. By looking at these three populations, they could control for other factors that could explain the drop in ER visits and hospitalizations, said George Thurston, the director of the Program in Exposure Assessment and Human Health Effects at NYU and one of the authors of the study. 

Researchers found the mean ambient sulfur dioxide levels dropped 90 percent  in the studied area after the plant closed. Sulfur dioxide is a gaseous air pollutant that reduces the lung’s ability to function, causes respiratory symptoms and has also been linked to heart disease. 

In this type of steel plant, coal is heated until it turns into coke, an ingredient used to make steel. When heated, coal releases carbon dioxide, sulfur dioxide and other pollutants. It also releases PM2.5, particles a hundred times thinner than a human hair that can reach people’s lungs and brains. Studies have found that working in a coke plant is a risk factor for developing chronic obstructive pulmonary disease, hypertension and cancer. 

“We do these accountability studies because we are taking more actions now to mitigate air pollution, and we want to see if there is an actual health benefit associated with it,” said Wuyue Yu, a Ph.D. candidate at NYU and the lead author of the study. “These kinds of studies should be done more to evaluate the actual health benefits to encourage more regulations.” 

The study’s authors  also hope this kind of research informs the type of regulations promulgated by government health and environment officials. For instance, the study found two components of PM2.5, sulfate and arsenic, dropped after the plant closed. This is important because research has recently shown that not all PM2.5 pollutants are created equal. 

“Sulfate particulate matter, the kind that is produced from coal, is worse for human health than other types of PM2.5. So, if you want to reduce one type, I would probably pick sulfate,” said Casey. “Understanding what the benefit is from removing a specific exposure is quite helpful to inform how we want to spend our policy dollars to improve people’s lives.” 

But the EPA regulates all particulate matter equally. 

“To protect public health, you don’t want to indiscriminately control any source,” Thurston said. “People are being made sick, and we want to know which type of pollution is doing it.” 

Although it’s hard to extrapolate the study’s findings to other coke plants, this is still evidence of what coke plants can do to nearby communities, which are often disadvantaged and don’t have the resources to deal with the health effects of air pollution, said Hanneman. 

“If the EPA is like,’ OK, we want to write a new regulation on coke plants,’ this should be the study that they go to first,” he said. 

The drop in hospitalizations and ER visits was more than researchers expected and was more significant for the elderly population, the study found. After three years, the total number of cardiovascular ER visits in the exposure site was 61 percent lower than expected and residents over 65 comprised 60 percent of this reduction.

In that sense, the EPA could be underestimating the health benefits of reducing fossil fuel pollution, said Thurston. 

“So many of the things we need to do to address climate change are good for us, and this is a good example,” Thurston said.