Waterford — The union that represents security guards at the Millstone Power Station has filed a complaint with the federal Occupational Safety and Health Administration over exposure to possibly harmful dust particles generated by a contractor working at Unit 2.  

James Foley, vice president of the United Government Security Officers of America Local 19, said the complaint was filed last week after a contractor doing maintenance work at the plant did drilling work that spread cement dust and other substances into the air around the worksite.

The worksite was not covered or contained, and security guards in the area were not provided with respiratory protective equipment, he said.

He said OSHA investigators were at the site on Monday to begin an inquiry into what happened. Officials at the OSHA office in Hartford confirmed that there is a pending complaint but would not provide further details.

The complaint was filed against G4S, the Florida-based company that provides security services at the nuclear power plant. There are about 200 security guards in the union, Foley said.

Foley said the union asked the contractor doing the work for a Safety Data Sheet on the substances being drilled, and none was provided. OSHA requires that companies keep SDS documents with information about the potentially hazardous substances in the workplace.

Foley said one security guard sought medical treatment for the exposure. The guard had an allergic reaction and respiratory problems, he said.

He said the contractor stopped working at the site after the complaint was filed. Dominion Resources, which owns Millstone, placed one of its site safety officials at the site to oversee the resumption of work, Foley said. The cement dust also has been cleaned from the area.

Foley said the complaint was added to one filed earlier by the union pertaining to security-related equipment.

G4S issued a statement Tuesday afternoon stating that it is committed to providing safe working conditions for employees.

"The concrete grinding work was stopped and the alleged hazards were investigated and necessary modifications were made by the Millstone Safety Department," the statement said.

Ken Holt, spokesman for Millstone, said the problem apparently occurred because of a faulty vacuum cleaner.

The workers, who he said were removing concrete on an intake structure, "were using a vacuum cleaner that wasn't working properly. The work was stopped until we determined that appropriate safety controls are in place."

He said the vacuum cleaner is now functioning properly and that the project has resumed.

"The health and safety of our workers is always our top priority," he said.

j.benson@theday.com

Twitter: @BensonJudy