Rick Georgeson of the DEC said air regulations require Lafarge to control dust in nine ways at the Ravena plant, including the use of electrostatic precipitators on kilns and covers for conveyor belts that carry materials about the plant. Trucks leaving the site are sprayed down with water, as are roadways.
Dust could also originate at the nearby Callanan Industries facility or the limestone quarry.
"There are permit conditions for all three of those facilities that are supposed to reduce the dust," Gerorgeson said. "We haven't had very many complaints at all, maybe two in the last couple or years, from residents."
Georgeson went on to say DEC staff would be able to microscopically determine the origin of dust in the event of complaints.
Stone said his observations show dust mitigation measures aren't adequate.
The Department of Health is in the midst of a public health assessment study for the area surrounding the Lafarge plant that will take into account data sources collected since the plant's opening in 1962.
In September, Stone said his studies of heavy metal levels in area wildlife revealed heightened levels of mercury in plants and animals. The DEC is drafting new mercury emission regulations that would cap emissions at the Ravena factory at 176 pounds per year.
"We're still in the process of that, and right now we're deciding whether to have a public hearing for that," Georgeson said. "There's no real hard and fast deadline for that."
The federal Environmental Protection Agency is also looking into imposing stricter regulations that would cap Lafarge's plant at 70 to 80 pounds per year, according to Reagan.
Reagan pointed to DEC data from an air quality monitoring station in Columbia County showing the airborne mercury levels there to be below those found in Albany County, and both well below the federal air quality standard.