Small crystalline silica particles may be hard to see, but they can cause big damage
When Kalie Boot watches a truck hauling sand to a hydraulic fracturing well site, she recognizes the mix of minerals and rock particles in the vehicle’s bed as integral to the oil and gas extraction process. She also knows the sand contains a deadly hazard.
An industrial hygienist with Encana’s strategic environment, health and safety team in Calgary, Boot points out that when the sand is moved from the truck to storage containers and from storage to the well, the substance can throw up harmful crystalline silica, a basic component of soil, sand, granite and other minerals. When workers chip, cut or grind ?materials that contain silica, it’s reduced to small particles they can breathe in. If workers inhale too many of those tiny fragments, they ?could eventually contract incurable silicosis. ?Exposure to silica can also cause lung cancer, chronic obstructive pulmonary disease, kidney disease and rheumatoid arthritis.
Encana insists on stringent safety procedures to tackle the risk at its fracking sites: ventilators to clean the air, restricted access to the dust source and respirators to prevent inhalation. The company also trains its services firms to ensure everyone who works at its wells understands the danger and how to deal with it.
“We’re even suggesting that some of our frac providers offer employees powered air-purifying respirators,” Boot says. She points out that workers overseeing the frac mixture ?process often sit in blender crew cabs that lack high-efficiency air-filtration systems. Powered air-purifying ?respirators (PAPRs) help keep those workers from inhaling the dust, ?delivering a stream of clean air ?without requiring uncomfortable face pieces.
Encana isn’t the only company concerned about crystalline silica. Many producers and services firms see this substance as a hazard to mitigate.
Workers exposed to high silica levels
A government of Alberta report suggests silica levels at certain oil and gas operations exceed the province’s occupational exposure limit (OEL). The government measured silica exposure levels at fracking and oilsands operations and in bulk plants. ?Researchers found that at fracking sites, airborne respirable silica levels averaged 0.086mg/m3, well above Alberta’s OEL of 0.025mg/m3. Levels at oilsands mining sites averaged 0.026mg/m3 and reached as high as 0.13mg/m3. Although levels at bulk plants averaged just 0.021mg/m3, ?investigators measured highs up to 0.048mg/m3.
Researchers considered differences in work practices and protective equipment used at particular sites. The investigators discovered that companies generally address the risk of silica exposure well — but not perfectly. For example, at fracking and oilsands sites, most workers wore proper protective gear, and companies provided health assessments and safety training. But at bulk plants, engineering and administrative controls were less common.
Researchers also noticed that workers commonly used dry sweeping to clean up spilled materials. This method can create more airborne dust. The Canadian Centre for Occupational Health and Safety (CCOHS) recommends workers use vacuums with HEPA filters instead.
In some cases, workplace habits undermined safety. For instance, even though many of the vehicles workers used had ventilation systems, drivers often left the windows open so dust easily made its way into the cabs.
PPE usage was high, but not ?100 per cent. Researchers monitored 32 workers and found that seven did not wear respirators. Most of the unprotected workers were employed at bulk plants and oilsands operations.
“It could be they just weren’t aware of the exposure levels,” says Diane Radnoff, a senior occupational hygienist with Alberta’s Ministry of Jobs, Skills, Training and Labour in Edmonton. She led the team that conducted the silica exposure study. Until recently, the industry has lacked the information it needed to reduce exposure risks, she says. “Sometimes employers give workers respirators, but the employers don’t know if the respirators are the correct ones for the exposure levels or even if the workers need respirators in the first place.”
The Alberta government’s results are consistent with those the ?United States’ National Institute for ?Occupational Safety and Health (NIOSH) discovered when its researchers delved into the risks of silica dust in fracking. Last year, NIOSH reported that proppant transfer belt operators and sand-mover operators face extremely high respirable silica levels — 0.327mg/m3 and 0.259mg/m3 on average, respectively.
Industry takes action
As Radnoff and her team present their findings about exposure risks to companies and industry associations, they’re also recommending ways for the sector to take precautions and handle materials safely.
One of the first lines of defence against any risk is substitution: use a product that is safer than the hazardous material. Man-made ceramics stand as one alternative to sand. But ceramics are expensive, so most companies prefer sand.
Instead of substitution, producers and services firms use engineering and administrative controls to battle the hazard. Dave Ayriss, a ?senior occupational hygienist at Golder Associates in Calgary, says safety smart companies use auger screws to deposit sand onto conveyor belts — a gentler and less dusty method than conventional means. Silica-conscious companies also shut dust sources such as sand-mover nozzles and feed hatches to reduce exposure.
“We see these changes as obvious, but sometimes they’re right under people’s noses and they don’t realize it,” Ayriss says.
Some companies are investing in new technologies to bust silica dust. Encana, for one, is testing a dust-suppressing liquid, which is sprayed onto the sand early in the process.
“If we can apply this solution at the mine, we’ll be safeguarding the health of everyone down the line,” Boot says.
But certain technologies need to be tweaked to be effective. Ayriss notes that one of Golder’s clients installed a baghouse filter to manage the dust. So far, the system hasn’t significantly reduced silica levels.
“I’m not sure too many companies are looking at that control,” he says. The client plans to adjust the filter, though, and Golder will ?revisit the site to see if the new ?configuration helps.
Alongside amended work processes and new technologies, companies turn to PPE for individual workers. When it comes to airborne hazards like silica dust, respirators are the obvious choice. But not all respirators are created equal. CCOHS recommends different types of respirators for different silica dust levels (see sidebar).
Ayriss adds that half-mask respirators are only acceptable where silica dust levels are less than 10 times the OEL. That fact means that in Alberta, workers should only use half-mask respirators where dust levels are less than 0.25mg/m3.
“In many cases at frac sites, silica concentrations are found in excess of 0.25mg/m3, so full-face respirators are required,” he says.
Set competition aside
Protective gear, ventilators, worker training and work flow analyses all play important roles in the industry’s fight against silica dust exposure. Co-operation may be another essential tool. Boot recommends producers and services firms collaborate through industry associations such as the Canadian Association of Petroleum Producers (CAPP) and the Petroleum Services Association of Canada (PSAC) ?to share as much information as possible. Working together, ?companies will better understand the hazard and uncover new methods to address it.
“Although it’s a competitive advantage to be ahead of another frac provider or producer from a business perspective, I don’t think it’s an advantage from a workers’ health perspective,” Boot says. “If we can pool information, it’s a great way to learn if the solutions are working.”
The Canadian Centre for Occupational Health and Safety recommends different types of respirators for different silica dust levels.
•Up to 0.5mg/m3: Particulate respirators equipped with N95, R95 or P95 filtering face pieces, except quarter-mask respirators. Additional acceptable filters are N99, R99, P99, N100, R100 and P100.
•Up to 1.25mg/m3: PAPRs with HEPA filters, or supplied-air respirators operated in a continuous-flow mode.
•Up to 2.5mg/m3: Air-purifying full-face piece respirators with N100, R100 or P100 filters, or PAPRs with tight-fitting face pieces and HEPA filters.
•Up to 25 mg/m3: Supplied-air respirators operated in pressure-demand or another positive-pressure mode.
Stefan Dubowski is a freelance writer based in Ottawa. He can be reached at email@example.com.
This article originally appeared in the Autumn 2014 issue of Canadian Oil & Gas Safety.
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