Planning Director Michael Thompson told the County Commissioners at a Tuesday meeting that the EPA voided the county's Early Action Compact - the ozone pollution plan - as a result of the mistakes.
"We didn't do anything wrong," Thompson said. "The state of Virginia goofed it up."
County Associate Planner Jill Baker said by phone Tuesday that the Virginia Department of Environmental Quality completed an air quality modeling report for the county, which was part of the county's Early Action Compact.
Baker said she didn't know the details of the report or what the errors were, but said she thought they were minor.
The modeling report must be corrected and then resubmitted to the EPA, Baker said.
Bill Hayden, spokesman for the Virginia Department of Environmental Quality, said Tuesday that employees who do the modeling reports were out of the office and that he didn't have any information on what the errors might be.
A modeling report is a computer analysis of air quality and takes into account such factors as traffic patterns and industrial pollution and helps keep track of the type of pollution in the air and where the pollution might end up, Hayden said.
Ground level ozone, commonly known as smog, is a toxic gas that, when inhaled, can cause respiratory problems, chest pain, sore throats and other breathing problems, according to the EPA. Ozone is formed when hot summer sun mixes with pollution from vehicles, industry, consumer products and power plants.
Washington County's average ozone level is slightly above the national standard.
The EPA formerly measured ground-level ozone with a one-hour standard of 125 parts per billion. In 1997, the method was switched to eight-hour readings - once an hour for eight hours each day - and the cutoff switched to 85 parts per billion.
The county's 2002 average was 87 parts per billion.
While the county's air is cleaner than that in some other areas in the state, it sometimes has high ozone levels because of pollution floating in from upwind areas, such as the Ohio River Valley, and the county's proximity to the Washington/Baltimore metropolitan area, county and environmental officials have said.
The county usually has only a few high-level ozone days, which are typically muggy days in August.