JACKSONVILLE, Fla. -- A sickness that recently took hold of several air traffic controllers at the Jacksonville International Airport has triggered some concerns about those who keep the skies safe for travelers.

Nearly one of every four air traffic controllers are on leave because of a problem at their workplace.

Air traffic controller and president of the local union Mike Flanagan said the people who work in a building next the JIA control tower had to breathe fumes that he said were hazardous.

He said those affected are the people who control most of the planes that fly over Northeast Florida.

"It was really a bad time," said Flanagan. "This is where the controllers work radar covering 6,200 miles of airspace, basically from Brunswick, Ga., to Cedar Key."

Flanagan said the problem began in late February during renovations. He said that was when adhesive poured on the roof leaked inside and released toxic fumes.

"Two of my co-workers became so seriously ill that we had to call the airport firefighters," Flanagan said.

The Federal Aviation Administration admitted there was a problem and that action was taken immediately, stating, "When a foul odor caused by re-roofing materials permeated the FAA approach control, FAA managers immediately took steps to correct the situation. Results of the air quality tests revealed levels were well below Occupational Safety and Health Administration standards."

The FAA said employees who reported they were affected by the odor have been permitted to take necessary leave to seek medical attention and to file necessary forms related to their medical conditions.

"They're absolutely, positively taking appropriate steps now, but for 11 days it was denial," Flanagan said.

He said during those 11 days, at least half the staff of 46 controllers reported some sort of symptoms, such as nausea, dizziness and breathing problems.

Flanagan said 10 remain out of work and that he's concerned those controllers might be forced into coming back too soon.

"It appears to me that there was no concern for the health and well-being of the controllers and that eventually trickles down to the health and well being of the flying public," Flanagan said.

The FAA said the illnesses did not put the flying public in danger. It said all of the shifts that are missed are filled by other workers, and that there is a limit to the number of days and hours any one controller can work.