Charleston International Airport is monitoring air quality in some construction areas of the terminal after asbestos-laced materials were discovered during demolition on two exterior walls.

The two areas include the front wall, which is being ripped away to be replaced with glass to allow more light into the building, and behind the outside wall of Concourse A. That area is being expanded to include a new consolidated security checkpoint and upper-floor administrative offices.

The 29-year-old terminal is in the throes of a $189 million makeover. Exposure to asbestos has been linked to cancer.

"The uncovering of concealed asbestos-containing material is not unusual in a building that is nearly 30 years old and in a construction project of this magnitude," said John Connell, deputy director of engineering and planning for the Charleston County Aviation Authority.

Preliminary test results indicate that the glue used to install vapor barriers or waterproofing material when the building was constructed in 1985 contain asbestos materials, the agency said in a statement.

"While we were demolishing those areas, we discovered that material," Connell said Wednesday. "It was concealed behind the walls. We stopped work immediately, had it tested and it was confirmed that it contained asbestos."

Airport officials notified the state Department of Health and Environmental Control, which was sending someone to the site Wednesday for an inspection and advice on remediation.

"We will proceed with the appropriate removal," Connell said.

The affected areas were already barricaded from the public through temporary construction walls when the materials with asbestos were discovered.

"They are not in a public area," Connell said.

The discovery is not expected to affect air travelers or visitors to the airport.

"We don't expect any impact on the operation of the airport," Connell said. "The airport remains a safe place to work and travel through."

Airport spokeswoman Charlene Gunnells said workers and tenants at the airport have already been notified of the asbestos discovery.

"The airport is acting swiftly to address this, and we want the traveling public to know that the airport is safe," she said.

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Before renovations began, the Aviation Authority hired experts to survey and test for any asbestos that might be in the terminal. Testing found limited asbestos-containing materials in the glue under vinyl flooring in a handful of areas in the airport, and it is being removed under state and federal guidelines.

Connell did not know if the work stoppage in affected areas will delay construction.

"It will add to the cost," Airports Director Paul Campbell said.

Efforts will be made to remove the material without disturbing it so it will not become airborne, Campbell said.

Terminal expansion and renovation involves adding five new gates, a third baggage carousel, a new rental car pavilion, consolidated security, a dome over the central hall, numerous other structural and cosmetic changes and lots more natural lighting.

The project is expected to be completed in August 2015.

Reach Warren L. Wise at 937-5524 or