OSHA has jurisdiction over the safety and health of workers, including workers involved in upstream oil and gas operations. OSHA's General Industry Standards (29 CFR 1910) and the General Duty Clause of the Occupational Safety and Health (OSH) Act both apply to the upstream industry. As part of the enforcement of these regulations, five OSHA regions located in areas of significant upstream activities use national, regional, and local emphasis programs to inspect oilfield worksites, including those that may have ongoing hydraulic fracturing operations.

The OSHA Permissible Exposure Limit (PEL) for silica is outlined in the OSHA Air Contaminants standard (29 CFR 1910.1000 Table Z-3.) The PEL for quartz, the common form of crystalline silica found in sand, is an 8-hour time-weighted average exposure to respirable dust calculated from the following formula:

PEL = 10 / [(% Silica) + 2]

The PEL is approximately equal to 0.1 mg/m³ for pure quartz silica. If other forms of crystalline silica are present, the PEL calculation must be modified per Table Z-3. Additionally, OSHA Directive CPL 03-00-007 National Emphasis Program – Crystalline Silica, has detailed information on silica hazards, guidelines for air sampling, guidance on calculating PELs for dust containing silica, and other compliance information.

Several OSHA standards and directives also cover operations that may expose workers to silica, including:

• Hazard Communication (29 CFR 1910.1200)
• Respiratory Protection (29 CFR 1910.134)

In addition to silica hazards, workers may be exposed to other worksite health hazards that can include exposure to diesel particulate and exhaust gases from equipment, high or low temperature extremes, high noise levels, and overexertion leading to sprains and strains. In addition, fatigue may be a concern due to long working hours. See OSHA's Oil and Gas Well Drilling and Servicing eTool website for more information about the standards that cover safety and health hazards at oil and gas extraction sites.

OSHA and the NIOSH have both been investigating worker safety and health hazards in oil and gas extraction, including chemical exposures during hydraulic fracturing operations. In general, OSHA acts in a regulatory capacity while NIOSH acts in a research capacity.

OSHA has jurisdiction over the safety and health of workers, including workers involved in upstream oil and gas operations. OSHA's General Industry Standards (29 CFR 1910) and the General Duty Clause of the Occupational Safety and Health (OSH) Act both apply to the upstream industry. As part of the enforcement of these regulations, five OSHA regions located in areas of significant upstream activities use national, regional, and local emphasis programs to inspect oilfield worksites, including those that may have ongoing hydraulic fracturing operations.

NIOSH made safety and health in the oil and gas extraction industry a priority focus area in 2005 by creating the Oil and Gas Extraction Council as a result National Occupational Research Agenda (NORA). The Council includes OSHA and industry leaders working cooperatively to address occupational safety and health issues, including an existing lack of information on occupational dust and chemical exposures associated with hydraulic fracturing. NIOSH established specific industry partnerships and initiated the NIOSH Field Effort to Assess Chemical Exposures to Oil and Gas Extraction Workers. Exposure to silica during hydraulic fracturing has been the focus of the NIOSH study to date.

Employers must determine which jobs expose workers to silica by collecting respirable dust samples and comparing the results to current exposure limits. Employers should consult with a trained occupational safety and health professional, such as a certified industrial hygienist, or contact OSHA's free on-site consultation service.

OSHA Directive CPL 03-00-007 National Emphasis Program – Crystalline Silica, has detailed information on silica hazards, guidelines for air sampling, guidance on calculating PELs for dust containing silica, and other compliance information.

If air samples show levels above OSHA's calculated PEL, employers are required to take actions to reduce worker exposures. However, both OSHA and NIOSH recommend that employers take action to keep worker exposures below the NIOSH REL.

In their study, NIOSH identified seven primary sources of silica dust exposure during hydraulic fracturing operations:

• Dust ejected from thief hatches (access ports) on top of the sand movers during refilling operations while the machines are running (hot loading).
• Dust ejected and pulsed through open side fill ports on the sand movers during refilling operations
• Dust generated by on-site vehicle traffic.
• Dust released from the transfer belt under the sand movers.
• Dust created as sand drops into, or is agitated in, the blender hopper and on transfer belts
• Dust released from operations of transfer belts between the sand mover and the blender
• Dust released from the top of the end of the sand transfer belt (dragon's tail) on sand movers.

OSHA sets enforceable permissible exposure limits (PELs) to protect workers against the health effects of exposure to hazardous substances. PELs are regulatory limits on the amount or concentration of a substance in the air. The OSHA general industry PEL for quartz, the common form of crystalline silica found in sand, is an 8-hour time-weighted average exposure to respirable dust calculated from the following formula:

PEL = 10 / [(% Silica) + 2]

The PEL is approximately equal to 0.1 mg/m³ for pure quartz silica. The PEL is outlined in 29 CFR 1910.1000 Table Z-3. If other forms of crystalline silica are present, the PEL calculation must be modified per Table Z-3.

The OSHA PEL is the legally enforceable regulatory limit. Employers are required to take actions to reduce worker exposures if air samples show levels above OSHA's calculated Permissible Exposure Limit (PEL).

The NIOSH Recommended Exposure Limit (REL) is a non-mandatory, recommended occupational exposure limit.

However, because OSHA recognizes that many of its PELs are outdated and inadequate measures of worker safety, both OSHA and NIOSH recommend that employers take actions to keep worker exposures below the NIOSH REL.

Silica sand is frequently used as a proppant during hydraulic fracturing. Other proppants can include sintered bauxite, ceramics, and resin-coated sand. Using alternative proppants is one way to reduce silica exposures. However, before using other proppants, it is important to evaluate the health hazards associated with them. If safe proppant alternatives are not feasible, then employers should monitor worker exposures, take measures to prevent exposures to silica, and inform workers of hazards. If appropriate precautions are taken, then the risks associated with using sand can be mitigated.

In addition to silica hazards, workers may be exposed to other worksite health hazards that can include exposure to diesel particulate and exhaust gases from equipment, high or low temperature extremes, high noise levels, and overexertion leading to sprains and strains. In addition, fatigue may be a concern due to long working hours.

Hydraulic fracturing sites also have safety hazards similar to those at other oil and gas drilling sites, including:

• Being struck by moving equipment, including motor vehicle accidents (primarily when traveling to and between well sites), tools, and falling objects.
• Poor lighting.
• Being caught in pinch points (such as hammer union wings and hammers, pump iron, and racks).
• Falling from heights.
• Being struck by high-pressure lines or unexpected release of pressure (for example, mismatched or worn hammer unions, line failure).
• Fires or explosions from flowback fluids containing ignitable materials (e.g., methane) and other flammable materials stored or used at the well site.
• Working in confined spaces, such as sand storage trailers, frac tanks, and sand movers without taking the required precautions.

See OSHA's Oil and Gas Well Drilling and Servicing eTool website for more information on safety and health hazards at oil and gas extraction sites.

OSHA's Hazard Communication Standard requires that employers provide their workers with training and information about hazardous chemicals used in the workplace. Employers must provide training and information to workers in a manner and language that the worker understands. Employers must prepare and implement a written hazard communication program, provide training and information on the hazards of silica and other chemicals used in the workplace, and provide workers access to Safety Data Sheets (SDSs) on silica sand and other hazardous chemicals they are exposed to during hydraulic fracturing operations.