Air pollution from data center power projects is a rising concern amid build-out

In a rural county south of Columbus, Ohio, a company specializing in on-site power generation for data centers is facing pushback from critics who warn of air pollution from its latest natural gas-fired project.

One state to the east, advocacy groups are challenging an air quality permit that the Pennsylvania Department of Environmental Protection issued in November 2025 for the 4.4-gigawatt Homer City Combined Cycle Plant, which will power a 3,200-acre data center campus.

Similar concerns have recently been raised with data center power projects in North Carolina and Georgia.

Air pollution is a growing concern for scientists and groups that track impacts from the 547 hyperscale-owned data centers in the US, as well as the 395 facilities under construction, according to second-quarter data from 451 Research's S&P Global Data Center KnowledgeBase.

Local reviews have been mixed for the 800-megawatt PowerConneX natural gas-fired system, proposed for the new data center near the Village of Ashville in Ohio.

Labor unions are supporting the project, citing new jobs and local tax revenue. So does the local school district, which PowerConneX has promised a $77.4 million donation if the project is approved.

Many residents, however, have voiced concerns over water resources and emissions from the 74 natural gas turbines the company plans to install.

"These gas turbines will run 24/7, and the air will carry what they burn across our village, past our schools, our homes, our fields, and to neighborhoods beyond," Charlina Hoswell told the Ohio Power Siting Board during an Aug. 19 public hearing about the project. "This is the air we breathe."

The new data center will be less than a mile from her home, Hoswell added.

Emissions, health care costs

US data centers were getting more than 55% of their power from fossil fuel-fired power plants as of 2024, according to the International Energy Agency. That trend is expected to continue for the next few years as developers increasingly turn to behind-the-meter solutions to avoid grid constraints and delays.

A study published in February by researchers at Harvard University estimated that hyperscalers operating between May 2024 and May 2025 accounted for more than 52 million metric tons of carbon dioxide emissions, equivalent to emissions generated from driving more than 12 million gasoline-fueled passenger cars for a year.

Federal and state policymakers seeking to rein in data center impacts on power bills are missing an important part of the cost equation, former officials with the US Environmental Protection Agency said during a Sept. 10 call with reporters.

"This massive AI build-out can have enormous consequences for Americans' health," said Lynn Goldman, a pediatrician and epidemiologist who served as an EPA assistant administrator for toxic substances under President Bill Clinton.

Pollution from data center electricity demand is estimated to reach $20 billion in annual health care costs by 2028, Goldman said, citing a soon-to-be published study by researchers from UC Riverside, Caltech, and the Rochester Institute of Technology.

Goldman listed pollutants associated with data center power consumption that concern her most: soot, smog, mercury, arsenic, sulfur dioxide, nitrogen oxides, per- and polyfluoroalkyl substances, and formaldehyde.

Earlier this year, Texas regulators approved what power developer Pacifico Energy Group LLC called the largest data center air permit in US history. The permit allows the GW Energy Center in West Texas alone to release 33 million metric tons of CO₂ and thousands of metric tons of air pollutants annually from the 35 natural gas-fired turbines and backup generators Pacifico plans to install.

In March, three Senate Democrats launched an inquiry into the Texas project and several other major data center developments, whose pollution levels, the legislators said, will rival those of US coal-fired power plants.

Data center damages, benefits vary

Health and social costs from the data center boom vary across the US, depending on the number of facilities in each state and the generation resources its grid relies on, said Nick Muller, a professor of economics, engineering, and public policy at Carnegie Mellon University.

Such costs, known as gross external damages, ranged from $2 billion to $5 billion in 2025 for Texas and Virginia, two states with substantial data center infrastructure, according to a National Bureau of Economic Research paper that Muller published in April. The study focused on premature mortality risk from local air pollution and included impacts such as reduced agricultural output and destructive weather events when calculating damages from greenhouse gas emissions.

In all, damage from US data center power consumption ranged between $10 billion and $33 billion in 2025, Muller found.

"The size, location, and projected power use from those planned facilities is pretty stunning," Muller said during an interview. "So we need to think carefully about that, both in the public discourse and as policymakers."

Muller's research also showed that the economic benefits of data center development vary widely across states when weighed against health impacts. In North Dakota and Wyoming, states that rely heavily on coal-fired electricity generation for data centers, calculated damages are five times and two times higher, respectively, than the states' gross domestic product, Muller's modeling showed.

At the same time, states and municipalities weigh the role of taxes and economic development in their areas.

For example, the Virginia Department of Taxation estimated that the existing sales tax benefit for data centers totaled $1.94 billion in 2025 for the state, the highest in the country. Loudoun County, Virginia, estimates that data centers will pay about $1.14 billion in real and personal property taxes in 2026, equivalent to 42% of the county's local tax revenue. The county is home to the largest concentration of data centers in the world.

Muller said preliminary nationwide comparisons suggest that "damages attributable to AI-related energy use are small relative to potential productivity gains."

Ohio power developer challenges testimony

In Ohio, health impacts from data centers remain a point of contention.

If running at 57% capacity, the 74 gas-fired turbines PowerConneX plans to build and operate would annually release 165 metric tons of nitrogen oxides, 229 mt of fine particulate matter, 42 mt of sulfur dioxide, and 188 mt of volatile organic compounds, according to projections from John Bangsund, the director of science and technology at the Better Data Center Project.

Such emissions could cause up to 11 premature deaths, 17 cases of asthma onset, and 580 lost workdays a year, Bangsund said in comments to the Ohio Power Siting Board. The state regulatory board held Sept. 9-11 hearings about data center power needs.

Global data center developer EdgeConneX Inc., which created PowerConneX to build on-site power systems in markets with limited grid resources, could not be reached for comment. EdgeConneX is a subsidiary of private equity firm EQT AB.

An attorney for PowerConneX asked the regulators to strike Bangsund's testimony and that of several area residents and two researchers, saying the siting board was the wrong venue for issues related to air pollution and health impacts. The attorney also questioned Bangsund's use of a US Environmental Protection Agency COBRA tool, typically used to measure health benefits from clean energy programs, to estimate pollution impacts from the data center's power system.

The board twice denied the company's request to exclude the testimonies, according to the Ohio River Valley Institute, a clean energy think tank whose experts were among those PowerConneX sought to exclude from the hearing Sept. 10.