OSHA INFOSHEET

In May 2012, NIOSH reported that workers may be exposed to 

dust with high levels of respirable crystalline silica (silica) during 

hydraulic fracturing. Silica is a common mineral found in the earth’s 

crust. It occurs primarily as quartz and is a major component of the 

sand, clay and stone materials used to make everyday products 

such as concrete, brick and glass. Large amounts of sand are 

frequently used in hydraulic fracturing operations (“fracking”).

What are the health hazards of silica?

•	 Silicosis is a lung disease caused by breathing in very small particles 

of silica that cause inflammation and scarring in the lungs and 

reduces the lungs’ ability to use oxygen. Workers who breathe silica 

dust day after day are at greater risk of developing silicosis. 

•	 Breathing in silica also increases the risk of lung cancer and other 

diseases, such as tuberculosis, chronic obstructive pulmonary 

disease, and kidney and autoimmune diseases. 

How are workers exposed to silica on hydraulic 

fracturing sites?

Dust containing silica can be released when sand is off-loaded 

from transport trucks and transported through movers, along 

transfer belts, and into blender hoppers. You can be exposed to 

silica if you breathe the dust. 

Primary sources where dust can be released include: 

•	 Thief hatches (access ports) on top of the sand movers while the

machinery is running during refilling (hot loading).

•	 Open side-fill ports on the sand movers during refilling operations.

•	 On-site vehicle traffic, such as sand trucks.

•	 Transfer belts under the sand movers.

•	 Sand poured into, or mixed in, the blender hopper and on transfer

belts.

•	 Operation of transfer belts between the sand mover and the blender.

•	 End of the sand transfer belt (dragon’s tail) on sand movers.

How do you know if silica is being released into 

the air?

To determine silica exposure levels, your employer should collect

air samples using devices that measure the amount of silica in a 

worker’s breathing zone. This enables employers to determine

which jobs may expose workers to silica and the levels of silica in 

the air. The OSHA permissible exposure limit for worker exposure

to silica is approximately 0.1 mg/m3 for pure quartz silica. 

Silica Exposure during Hydraulic Fracturing

The National Institute for Occupational Safety and Health (NIOSH) identified exposure 

to airborne silica as a health hazard to workers conducting some hydraulic fracturing 

operations. This INFOSHEET discusses the hazards of silica, how you can be exposed, what

actions employers must take to reduce exposures, and your rights as a worker.

Silicosis-damaged lung.

Photo credit: CDC

Airborne silica dust at sand 

mover and transfer system.

Photo credit: NIOSH
How can worker exposures to silica in the air 

be reduced?

 Reduce the amount of silica dust.

Work practices that can be used now:

•	 Cap unused fill ports on sides of sand mover.

•	 Reduce distance that sand falls (e.g., between the end of the dragon’s

tail and T-belts).

•	 Limit the number of workers and the time that workers must spend in

areas where silica dust is in the air.

•	 Consider modifications to equipment so that dust operations can be

performed remotely.

•	 Apply water-based products to roads and around the well site to

reduce the amount of airborne dust.

Work practices that involve equipment modification:

•	 Enclose points where dust is released (e.g., skirting around bottom/

sides of sand movers, shrouding around and at the end of the 

dragon’s tail).

•	 Use door seals and HEPA filtration on enclosed operator cabs or

booths where possible. 

•	 Use local exhaust ventilation on machines or equipment to collect

dust.

•	 Replace transfer belts with screw augers on sand movers in new

designs or retrofits.

 Use respirators when required.

When respirators are required, your employer must have a 

respiratory protection program that meets the requirements of 

OSHA’s Respiratory Protection standard (29 CFR 1910.134). This

program must include proper respirator selection, fit testing, medical 

evaluations, and training. All respirators need to be NIOSH-approved.

 Inform and train workers on the hazards of silica and 

other chemicals. 

	 OSHA’s Hazard Communication standard requires your employer to

provide workers training and access to safety data sheets (SDSs) on 

silica sand and other hazardous chemicals used or produced during 

hydraulic fracturing operations.

WORKER RIGHTS

Under OSHA law, employers

have the responsibility to 

provide a safe workplace. 

Workers must receive 

information and training (in 

a language and vocabulary 

they can understand) about 

workplace hazards, methods to 

prevent them, and the OSHA

standards that apply. 

Workers can review records 

of work-related injuries and 

illnesses as well as get copies 

of test results that find and 

measure hazards. 

Workers may confidentially 

ask OSHA to inspect their

workplace if they believe that 

their employer is not following 

OSHA standards or that there

are serious hazards.

Workers have the right to 

use their rights under the law, 

including their right to report a 

work-related injury or illness, 

free from discrimination or 

retaliation. 

For more information, to ask a

question, or to file a complaint, 

visit www.OSHA.gov or call

1-800-321-OSHA (6742). It is

confidential.

This InfoSheet is advisory in nature and informational in content. It is not a standard or regulation, and it neither

creates new legal obligations nor alters existing obligations created by OSHA standards or the Occupational Safety 

and Health Act (OSH Act). Pursuant to the OSH Act, employers must comply with safety and health standards and

regulations issued and enforced either by OSHA or by an OSHA-approved state plan. In addition, the Act’s General

Duty Clause, Section 5(a)(1), requires employers to provide their employees with a workplace free from recognized

hazards likely to cause death or serious physical harm. The mention of any nongovernmental organization or li

to its web site in this InfoSheet does not constitute an endorsement by OSHA of that organization or its products,

services, or web site.

OSHA 3622-12 2012