CHARLOTTE, N.C. — Air pollution at a historic cemetery in Charlotte is speeding up the deterioration of headstones, some dating back to the 1760s.

The Steele Creek Presbyterian Church Cemetery is the burial site of 13 known revolutionary war veterans, according to the consulting preservation planner with the Charlotte-Mecklenburg Historic Landmarks Commission, Tommy Warlick.

"There are about 200 headstones that are between the years of 1763 and 1820,” he said.

Warlick adds that many of the headstones were carved by the Bingham family, the prominent stone carvers of the day.

“Of those 200 stones, 74 of them were created by the Bingham Family Stone Carvers Shop,” he said. “This is the biggest collection of Bingham stones known."

With so much history here, Warlick says the commission wants to save it.

The cemetery sits near the airport and off of a road with a lot of traffic.

Warlick says the commission thinks the increase in air traffic and road traffic is contributing to the deterioration.

“All the exhaust fumes that are coming from that, of course, contain sulfuric acid and contain nitric acid,” he said. "And when combined with water that creates acid rain and acid rain actually breaks down these stones. Most of the old headstones weren’t made out of granite or marble like they are today. They were primarily made of limestone or soapstone or sandstone and acid rain actually cause the constituent element of these stones to start breaking down or dissolving.”

He also referenced greenish-looking material growing on the headstones.

He pulled a piece off that was green on top and black on the bottom.

"So you see the black on the bottom side, that's the carbon that's generated by virtue of the sulfuric acid causing these stones to deteriorate away,” he said. “The green stuff then on the opposite side, that's the organic material that's eating this stuff. By virtue of it eating that carbon and living off that carbon, it's causing additional deterioration.”

He says sometimes it’s easy to clean off, but sometimes it’s not.

That’s why the commission cleans these stones with a biodegradable material called D2.

"Even after you leave, it sort of penetrates and it continues working and it will actually help preserve the stone for anywhere from eight to 10 years after it's been applied,” he said.

In honor of the commission’s 50th anniversary, they’re asking volunteers to come out on Saturday, April 22 to help clean the stones.

Here are the details:

• The Steele Creek Cemetery Headstone Preservation Event is Saturday, April 22 from 9 a.m. to noon
• It's at the Steele Creek Cemetery, 7311 Steele Creek Road, Charlotte (beside the former Steele Creek Presbyterian Church)
• The event is rain or shine
• Prepare to get wet and dirty! Suggestions: wear old clothing and closed-toe shoes
• No experience is necessary
• They will supply all the needed tools and supplies
• Please register by April 20 
• Questions? Contact them!

Warlick hopes people can join. He says it’s important to preserve this history.

“It’s the story of us,” he said. "That’s the thing that’s so interesting.”