DEQ finds Sterling data center emissions below permit limits

Loudoun County, July 21, 2026

The Vantage VA2 data center in Sterling released 38.9 tons of fine particulate matter, airborne particles small enough to reach the lungs and bloodstream, in 2025, 69% of its permitted annual limit, according to an April 27, 2026 assessment by the Virginia Department of Environmental Quality. The state review disputes a February 27, 2026 report commissioned by the Piedmont Environmental Council that modeled health damages from the facility's maximum allowed emissions.

Eight natural gas turbines serve as the primary power source at the Glenn Drive site, with 42 diesel generators reserved for emergencies and testing. DEQ issued the facility's air permit on September 15, 2023, and the turbines began normal operations on April 1, 2024. Across five regulated pollutants, the agency put 2025 emissions at 28% to 69% of permitted caps, drawing on facility reports and a September 2024 stack test.

Why the estimates differ

The PEC report, conducted by Michael Cork, projected that emissions at the permitted maximum could cause $53 million to $99 million a year in health-related damages and an added 3.4 to 6.5 deaths annually across the affected region, Loudoun Now reported. Those projections assumed emissions at the full permitted level; the study did not measure the facility's actual output.

DEQ's assessment responds that the report treated every turbine and generator as one combined source even though the units do not run at the same time outside maintenance, and that it relied on two federal screening models the agency considers unsuited to judging a single facility. On that basis, DEQ concluded the report's health estimates were overstated at least tenfold.

PEC President Chris Miller told Loudoun Now that cumulative emissions from many small permits go uncounted across the region. In an April 30, 2026 response, the council said the two organizations were measuring different things: DEQ permit compliance, PEC health risk.

What the air monitors show

Since February 25, 2026, DEQ has operated small air sensors across the Sterling and Ashburn area under an EPA-funded monitoring project, tracking fine particles, carbon monoxide and nitrogen dioxide near the county's data center cluster.

In a July 2, 2026 analysis covering March 3 through July 1, the agency reported daily fine-particle averages below both federal benchmarks at every site, with site means between 3.8 and 5.9 micrograms per cubic meter against the 9.0 annual standard. Peak hourly carbon monoxide readings reached 3.0 parts per million; the hourly standard is 35. DEQ cautions that the sensors establish trends but cannot determine formal compliance, which requires regulatory monitors.

Vantage vice president Mark Freeman told Loudoun Now the company consistently operates below its permitted limits. Vantage also confirmed to DEQ in March 2026 that it plans to shut down the turbines and take primary power from the grid; the assessment states that timing depends on Dominion Energy's schedule for upgrading transmission lines in Loudoun County.

The monitoring project continues through summer 2026, with DEQ targeting updated analyses each Friday. The sensors move next to Prince William County's data center corridor, on a start date DEQ lists as undetermined.