A worker stands on top of a storage bin on July 27, 2011, at a drilling operation in Claysville, Pa. The dust is from powder mixed with water for hydraulic fracturing.
The sand keeps the cracks propped open so that oil and gas are released.
But sand is basically silica — and breathing in silica is one of the oldest known workplace dangers. Inside the lungs, exposure to the tiny particles has been shown to sometimes lead to serious diseases like silicosis and cancer.
Traditionally, silica exposure has been associated with jobs like mining, manufacturing and construction. But, as Esswein, a researcher with the National Institute for Occupational Safety and Health, and other safety experts have started to realize, some workers in the newly burgeoning fracking industry may be at risk, too, because of their exposure to silica dust.
"When sand was handled — that is, when it was transported by machines on site, or whenever these machines that move sand were refilled — dust, visible dust was created," Esswein says.
Dust blows off a pile of fracking sand at a mine near Chippewa Falls, Wis., on Dec. 15, 2011. Some of the air samples the National Institute for Occupational Safety and Health experts collected at fracking sites had such high levels of silica that the respirators typically worn by workers wouldn't offer enough protection, according to NIOSH standards.
He was visiting fracking sites because he wanted to study the potential chemical hazards for oil and gas workers, and he initially figured he and his colleagues would probably assess workers' exposures to chemicals like drilling fluids. But when he saw the plumes of dust coming off the sand-handling machines and surrounding workers, he realized it could be a real hazard. The government has long set limits on how much workers can inhale.
"Knowing what I know about silica and respirable dust, that was the particular chemical that we chose to look at," Esswein says.
He and his colleagues visited 11 fracking sites in five states: Arkansas, Colorado, North Dakota, Pennsylvania and Texas. At every site, the researchers found high levels of silica in the air. It turned out that 79 percent of the collected samples exceeded the recommended exposure limit set by Esswein's agency.
There were some controls in place, says Esswein, who notes that "at every site that we went to, workers wore respirators."
But about one-third of the air samples they collected had such high levels of silica, the type of respirators typically worn wouldn't offer enough protection.
These unexpected findings have come just as federal safety officials are trying to set stricter controls on silica for all industries. Some proposed new rules have been under review at the White House Office of Management and Budget for more than two years.
Peg Seminario, director of safety and health with the AFL-CIO, a group of unions that has been pushing for stronger silica regulation, says the situation with fracking is a wake-up call.
"Hopefully it will give some impetus for the need for the silica regulation — that there is a whole other population at risk and those numbers are potentially growing," says Seminario.
A local contractor closes the valve on his tanker truck on July 27, 2011, after watering the roads to help keep down dust at a hydraulic fracturing operation in Claysville, Pa.
Workplace inspectors with the Occupational Safety and Health Administration wouldn't have been aware of this potential risk for fracking workers before this recent study because, unless they receive a complaint or there's an accident, they generally don't see the process of hydraulic fracturing. That part of setting up a well happens quickly — and once a well is up and running, contractors move on to the next one.
Government officials and the fracking industry say they're now working together to reduce workers' exposures. They started with quick fixes, like putting up warning signs and simply closing hatches on sand-moving machines.
Some oil and gas companies are also testing new technologies. Tim Hicks, a safety expert with Encana Corp., says they've been trying vacuum systems that attach to sand-moving machines and suck up the dust.
The results so far are encouraging, Hicks says, but his company is still testing to see how much of a reduction in airborne silica is reasonably achievable.
"We'd like to envision a site that, you know, we could handle sand and sequester it all, and perhaps someday not need to use respirators," says Hicks.
He says he's not sure whether that goal is possible, or how long it would take to get to that point. "But I can say that at the rate we're going," Hicks says, "we're much more likely to hit that [target] than we were prior to this issue being recognized."
Hicks says he has only been working in this part of the oil and gas business for a few years and couldn't speculate as to why the industry didn't recognize this potential health risk earlier. People, he says, seemed to think the dust was basically just dirt.