Hazard Alert - Exposure to Silica

8/18/2019 Hazard Alert - Exposure to Silica

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Worker Exposure to Silica during HydraulicFracturing

The National Institute for Occupational Safety and Health (NIOSH) identied exposureto air!orne silica as a health ha"ard to #orkers conducting so$e hydraulic fracturing

operations during recent eld studies% Crystalline silica is a common mineral found in the earth’s crust. It occurs primarily as quartz andis a major component of the sand, clay and stone materials used to make every day products

such as concrete, brick and glass.

Respirable crystalline silica is the portion of crystalline silica that is small enough to enter thegas-echange regions of the lungs if inhaled! this includes particles "ith aerodynamic diameters

less than approimately #$ micrometers %&m'.

Introduction

(ydraulic fracturing or )fracking) is a process used to )stimulate) "ell production in the oil andgas industry. It is not a ne" process, but its use has increased signi*cantly in the last #$ years

because of ne" horizontal drilling and multi-stage fracking %or )completions)' technologies thatimprove access to natural gas and oil deposits. It involves pumping large volumes of "ater and

sand into a "ell at high pressure to fracture shale and other tight formations, allo"ing oil and gasto +o" into the "ell.

I(/s recent *eld studies sho" that "orkers may be eposed to dust "ith high levels of respira!le crystalline silica %called )silica) in this (azard 0lert' during hydraulic fracturing.

1his (azard 0lert discusses the health hazards associated "ith hydraulic fracturing and focuseson "orker eposures to silica in the air. It covers the health e2ects of breathing silica,

recommends "ays to protect "orkers, and describes ho" (0 and I( can help. 3orkers andemployers need to be a"are of the hazard that silica dust poses. 4mployers must ensure that"orkers are properly protected from eposure to silica. 1his (azard 0lert also provides a brief

summary of other health and safety hazards to "orkers conducting hydraulic fracturing activities.


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Silica dust cloud !y #orker deli&ering sand fro$ sand $o&er to transfer !elt%'hoto credit NIOSH

OSH and the NIOSH have been investigating "orker safety and health hazards in oil and gasetraction, including chemical eposures during hydraulic fracturing operations.

OSH has jurisdiction over the safety and health of "orkers, including "orkers involved inupstream oil and gas operations. 1he 5eneral 6uty Clause of the ccupational afety and (ealth%(' 0ct and (0/s 5eneral Industry tandards %78 C9: #8#$' apply to the upstream industry.0s part of the enforcement of these regulations, *ve (0 regions located in areas of signi*cant

upstream activities use national, regional, and local emphasis programs to inspect oil*eld"orksites, including those that may have ongoing hydraulic fracturing operations.

NIOSH made safety and health in the oil and gas etraction industry a priority focus area in 7$$;by creating the ational ccupational :esearch 0genda %:0' il and 5as 4traction Council,"hich includes (0 and industry leaders in a cooperative e2ort to address occupational safetyand health issues. 1o address an eisting lack of information on occupational dust and chemicaleposures associated "ith hydraulic fracturing, I( established speci*c industry partnershipsand initiated the NIOSH Field Efort to Assess Chemical Exposure Risks to Gas and Oil Workers ?69, @ pagesA. 4posure to silica during hydraulic fracturing has been the focus of the I(

study to date.

Why is silica a concern for #orkers during hydraulic fracturing*

+ecent NIOSH eld studies identied o&erexposure to air!orne silica as a healthha"ard to #orkers%

Silica dust clouds fro$ deli&ery trucks loading into sand $o&ers%'hoto credit NIOSH

http://www.cdc.gov/niosh/docs/2010-130/pdfs/2010-130.pdfhttp://www.cdc.gov/niosh/docs/2010-130/pdfs/2010-130.pdfhttp://www.cdc.gov/niosh/docs/2010-130/pdfs/2010-130.pdf


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Barge quantities of silica sand are used during hydraulic fracturing. and is delivered via truckand then loaded into sand movers, "here it is subsequently transferred via conveyer belt and

blended "ith other hydraulic fracturing +uids prior to high pressure injection into the drilling hole. 1ransporting, moving, and re*lling silica sand into and through sand movers, along transfer belts,and into blender hoppers can release dusts containing silica into the air. 3orkers can be eposed

if they breathe the dust into their lungs.

I( identi*ed seven primary sources of silica dust eposure during hydraulic fracturingoperations

6ust ejected from thief hatches %access ports' on top of the sand movers during re*lling

operations "hile the machines are running %hot loading'.

6ust ejected and pulsed through open side *ll ports on the sand movers during re*lling

operations

6ust generated by on-site vehicle traDc.

6ust released from the transfer belt under the sand movers.

6ust created as sand drops into, or is agitated in, the blender hopper and on transfer

belts.

6ust released from operations of transfer belts bet"een the sand mover and the blender!

and

6ust released from the top of the end of the sand transfer belt %dragon’s tail' on sand

movers.

n O&er&ie# of the ,Fracking, 'rocess

1he process kno"n as )fracking) has long been used to etract oil from depleted "ells. It is no""idely used across the country to tap previously unreachable oil and natural gas locked "ithindeep rock formations.


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#. 3ell may be bored usingdirectional drilling, a methodthat allo"s drilling in verticaland horizontal directions to

depths of more than #$,$$$ ft.%E,$@F m'

7. Barge amounts of "ater,sand and chemicals are

injected into the "ell at highpressure, causing *ssures in

the shale

E. and +o"s into the *ssures,keeping them open so that the

oil or natural gas from theshale can +o" up and out of

the "ell

5raphic 6oug tevensCopytright 7$#7, Bos 0ngeles 1imes

:eprinted "ith permission.

9racturing +uid is made up of a base +uid, proppant, and chemical additives. 3ater accounts forabout 8$ percent of the fracturing miture and sand accounts for about 8.; percent. Chemicalsaccount for the remaining one half of one percent of the miture. 1he base +uid applies pressureto the formation and delivers the proppant to the fractures.

1he !ase -uid is usually "ater, but can include methanol, liquid carbon dioide, and lique*ed

petroleum gas.

'roppant consists of particles that hold open the fractures created by hydraulic fracturing,allo"ing the oil and gas to +o" out of the formation and into the "ell bore. Silica sand isfrequently used as a proppant. ther proppants can include sintered bauite or ceramics, andresin-coated sand.

.he$ical additi&es include friction reducers, scale inhibitors, solvents, acids, gelling agents,and biocides that are added to protect equipment, reduce pumping requirements, and maintainthe integrity of the oil or gas formation.

1he (0 general industry ?4B for quartz, the common form of crystalline silica found in sand, isan F-hour time-"eighted average eposure to respirable dust calculated from the follo"ing

formula.

!

"E# $

%& Silica' ( )

1he ?4B is approimately equal to $.# mgGmE for pure quartz silica.

1he ?4B is outlined in 78 C9: #8#$.#$$$ 1able H-E. If other forms of crystalline silica are present,the ?4B calculation must be modi*ed per 1able H-E.

1he I( :4B is a *ed value of $.$; mgGmE.

NIOSH Findings on Worker Exposures to Silica

In cooperation "ith oil and gas industry partners, I( collected ## full shift air samples at ##hydraulic fracturing sites in *ve states %0rkansas, Colorado, orth 6akota, ?ennsylvania, and

1eas' to determine the levels of "orker eposure to silica at various jobs at the "orksites. =anyair samples sho"ed silica levels for "orkers in and around the dust generation points above

de*ned occupational eposure limits.i

f the ## samples collected

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9994https://www.osha.gov/dts/hazardalerts/hydraulic_frac_hazard_alert.html#ihttps://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=standards&p_id=9994https://www.osha.gov/dts/hazardalerts/hydraulic_frac_hazard_alert.html#i


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@JK sho"ed silica eposures greater than the calculated (0 ?4B.

J8K sho"ed silica eposures greater than the I( :4B of $.$; milligrams per cubic

meter %mgGmE'.

8K of all samples sho"ed silica eposures #$ or more times the ?4B, "ith one sample

more than 7; times the ?4B.

E#K of all samples sho"ed silica eposures #$ or more times the :4B, "ith one sample

more than #$$ times the :4B.

Silica dust !y #orker conducting sand transfer operations% 'hoto sho#s sand $o&er and transfersyste$%

'hoto credit NIOSH

/eter$ining #orker exposure le&els is i$portant for selecting the right type of control$easures0 including engineering controls and respiratory protection% For exa$ple0half1face respirators are not protecti&e for silica le&els o&er 23 ti$es the exposure

li$it%

I( found that sand mover and blender operators, and "orkers do"n"ind of these operations%especially during hot loading', had the highest silica eposures. 3orkers up"ind and not in the

immediate area of sand movers %sand delivery truck spotters' also had eposures above theI( :4B, possibly from the dust created by traDc at the "ell site. 3orker and area samples

collected in enclosed but non-*ltered cab vehicles %e.g., chemical and blender trucks' "ere abovethe :4B, even "hen spending most of the day in the cab. 3orker and area samples collected in

enclosed vehicles "ith air conditioning and *ltration %e.g., data vans' had silica eposures belo"the I( :4B.

i 4mployers are required to take actions to reduce "orker eposures if air samples sho" levels above(0’s calculated ?ermissible 4posure Bimit %?4B'. 1he (0 ?4B is the legally enforceable regulatorylimit. 1he I( :ecommended 4posure Bimit %:4B' is a non-mandatory, recommended occupationaleposure limit. (o"ever, because (0 recognizes that many of its ?4Bs are outdated and inadequate

measures of "orker safety, both (0 and I( recommend that employers take actions to keep"orker eposures belo" the I( :4B.

Health Ha"ards of Silica


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(ydraulic fracturing sand contains up to 88K silica. >reathing silica can cause silicosis. ilicosis isa lung disease "here lung tissue around trapped silica particles reacts, causing in+ammation andscarring and reducing the lungs/ ability to take in oygen.ii 3orkers "ho breathe silica day afterday are at greater risk of developing silicosis. ilica can also cause lung cancer and has been

linked to other diseases, such as tuberculosis, chronic obstructive pulmonary disease, and kidneyand autoimmune disease.iii

ii I(


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What can !e done at hydraulic fracturing #orksites to protect#orkers fro$ exposure to silica*

Lnder the ccupational afety and (ealth 0ct of #8J$, employers are responsible for providingsafe and healthy "orking conditions for their "orkers. 4mployers must determine "hich jobs

epose "orkers to silica and take actions to control overeposures and protect "orkers. 0

combination of engineering controls, "ork practice, protective equipment, and productsubstitution "here feasible, along "ith "orker training, is needed to protect "orkers "ho are

eposed to silica during hydraulic fracturing operations.

One .a, to reduce silica exposures is to use alternati/e proppants %e0*0- sintered 1auxite-ceramics- resin2coated sand' .here 3easi1le. (o"ever, before using other proppants, it is

important to evaluate the health hazards associated "ith them. If safe proppant alternatives arenot feasible, then employers should monitor "orker eposures, take measures to prevent

eposures to silica, and inform "orkers of hazards, as described belo".

5onitor the air to deter$ine #orker exposures to silica

Collect respira!le dust samples to determine "hich jobs epose "orkers to silica above

eposure limits. 4mployers should consult "ith a trained occupational safety and healthprofessional, such as a certi*ed industrial hygienist, or contact (0’s free on-siteconsultation service.

If air samples sho" levels above (0’s calculated ?4B, employers are required to take

actions to reduce "orker eposures. (o"ever, both (0 and I( recommend thatemployers take the actions belo" to keep "orker eposures belo" the I( :4B.

conceptual exa$ple of dust control technologies !eing used !y industry%'hoto credit Frac Sand /ust .ontrol 66.

conceptual exa$ple of a !aghouse asse$!ly on the !ack of a truck%I$age credit NO7 ppco

https://www.osha.gov/pls/oshaweb/owasrch.search_form?p_doc_type=OSHACT&p_toc_level=0https://www.osha.gov/pls/oshaweb/owasrch.search_form?p_doc_type=OSHACT&p_toc_level=0


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conceptual exa$ple of a scre# auger retrot asse$!ly%I$age credit NIOSH

.ontrol dust exposures !y i$pro&ing existing engineering controls and safe #ork practices

4ngineering controls and "ork practices provide the best protection for "orkers and must beimplemented *rst, before respiratory protection is used. 3orking "ith industry partners, I(

has identi*ed the follo"ing control options for hydraulic fracturing operations

Short1ter$ #ork practices and procedural changes that can !e i$ple$ented 8uickly

5andate the capping of unused ll ports (e%g%0 ca$ lock caps) on sand $o&ers .

ecuring unused *ll ports can help reduce the dust released, especially during *lling.

+educe the drop height !et#een the sand transfer !elt and T1!elts and !lender

hoppers. Bimiting the distance that sand falls through the air can help reduce dust.

6i$it the nu$!er of #orkers0 and the ti$e #orkers $ust spend in areas "heredust and silica levels may be elevated, and consider #ays to perfor$ dustyoperations re$otely to completely remove employees from these areas.

pply fresh #ater to roads and around the #ell site to reduce the dust%

Practices that involve equipment changes

Enclose points #here dust is released. Install thick plastic stilling or staging curtains

around the bottom sides of the sand movers to limit dusts released from belt operation.4nclosures can also be added along and at the ends of the sand transfer belt.

3here possible, use enclosed ca!s or !ooths% Consider con*guring operator cabs and

booths "ith (4?0 *ltration and climate controls to further protect "orkers.

9se local exhaust &entilation to collect silica-containing dusts and prevent dust

escape. Install dust collection systems onto machines or equipment that can release dust.

+eplace transfer !elts #ith scre# augers on sand $o&ers in ne# designs or

retrots. 6ust can be released from the sand moving belt under the sand movers fromthe actions of belt movement or vibration. =oving sand through an auger system ratherthan a belt "ill help contain the sand and reduce dust release.

'ro&ide respiratory protection #hen it is needed to protect #orkers


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3hen engineering and "ork practices controls are not feasible, "hile they are beingimplemented, or "hen they do not reduce silica eposures belo" (0 ?4Bs, employers mustprovide "orkers "ith respirators. 3henever respirators are used, the employer must have a

respiratory protection program that meets the requirements of (0’s :espiratory ?rotectiontandard %78 C9: #8#$.#E@'. 1his program must include proper respirator selection, *t testing,

medical evaluations, and training.

If respirators are provided, use at least a I(-approved 8; respirator. If the silica level

is more than #$ times the ?4B, a half-face respirator is not protective and a respirator thato2ers a greater level of protection %e.g., a full-facepiece respirator, "hich "ill protect"orkers at silica levels up to ;$ times the ?4B' must be used. 9ull-face po"ered air-purifying respirators %?0?:' provide more protection than half-face air-purifyingrespirators. In general, "orkers *nd ?0?:s to be more comfortable.

NIOSH1appro&ed N:; ltering facepiece (top) and elasto$eric (!otto$) half1face respirators can !eused only if silica concentrations are less than 23 ti$es the 'E6%

9or more information, see (0’s afety and (ealth 1opics page and e1ool on respiratoryprotection.

'ro&ide training and infor$ation to #orkers a!out the ha"ards of silica and otherche$icals

(0/s (azard Communication tandard requires that employers provide their "orkers "ithtraining and information about hazardous chemicals used in the "orkplace.Employers must

provide training and information to workers in a manner and language that the worker understands. 4mployers must

?repare and implement a "ritten hazard communication program.

?rovide training and information on the hazards of silica and other chemicals used in the

"orkplace.

?rovide "orkers access to afety 6ata heets %6s' on silica sand and other hazardous

chemicals they are eposed to during hydraulic fracturing operations

https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=12716https://www.osha.gov/SLTC/respiratoryprotection/index.htmlhttps://www.osha.gov/SLTC/etools/respiratory/index.htmlhttps://www.osha.gov/SLTC/etools/respiratory/index.htmlhttps://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10099https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=12716https://www.osha.gov/SLTC/respiratoryprotection/index.htmlhttps://www.osha.gov/SLTC/etools/respiratory/index.htmlhttps://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=STANDARDS&p_id=10099


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(0 recently revised the (azard Communication tandard to conform "ith the 5lobally(armonized ystem of Classi*cation and Babeling of Chemicals %5('. )=aterial afety 6ata

heets) %=6s' are no" referred to as 6s, and the information on 6s "ill be presented inthe standard #-section format. :efer to (0/s (azard Communications page to get more

information.

.onsider $edical $onitoring for #orkers #ho are exposed to silica

0s part of its ational 4mphasis ?rogram on ilica, (0 recommends that employers medicallymonitor all "orkers "ho may be eposed to silica dust levels at or above one-half the ?4B.

:ecommended medical tests include

0 medical eam that focuses on the respiratory system and includes a "ork and medical

history

0 chest N-ray, evaluated by a quali*ed professional as described in 6irective C?B $E-$$-

$$J

(0 recommends that these tests be repeated every three years if the employee has less than

#; years of silica eposure, every t"o years if the employee has #; to 7$ years of eposure, andevery year if the employee has 7$ or more years of eposure.

ee ) A Guide to Workin* Sa3el, With Silica0 I3 It4s Silica- It5s Not 6ust 7ust ) , 7# pagesA.%L.. 6epartment of Babor and I(' for more information about the hazards of silica andprotecting "orkers from silica eposures.

What additional health and safety ha"ards exist during hydraulicfracturing*

In addition to silica hazards, "orkers may be eposed to other "orksite health hazards that caninclude eposure to diesel particulate and ehaust gases from equipment, high or lo"

temperature etremes, high noise levels, and overeertion leading to sprains and strains. Inaddition, fatigue may be a concern due to long "orking hours.

(ydraulic fracturing sites also have safety ha"ards similar to those at other oil and gas drillingsites, including

>eing struck by moving equipment, including motor vehicle accidents %primarily "hen

traveling to and bet"een "ell sites', tools, and falling objects.

?oor lighting.

>eing caught in pinch points %such as hammer union "ings and hammers, pump iron, and

racks'.

9alling from heights.

>eing struck by high-pressure lines or unepected release of pressure %for eample,

mismatched or "orn hammer unions, line failure'.

9ires or eplosions from +o"back +uids containing ignitable materials %e.g., methane' and

other +ammable materials stored or used at the "ell site.

https://www.osha.gov/dsg/hazcom/index.htmlhttps://www.osha.gov/dsg/hazcom/index.htmlhttps://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=DIRECTIVES&p_id=3790https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=DIRECTIVES&p_id=3790http://www.cdc.gov/niosh/pdfs/silicax.pdfhttps://www.osha.gov/dsg/hazcom/index.htmlhttps://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=DIRECTIVES&p_id=3790https://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=DIRECTIVES&p_id=3790http://www.cdc.gov/niosh/pdfs/silicax.pdf


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3orking in con*ned spaces, such as sand storage trailers, frac tanks, and sand movers

"ithout taking the required precautions.

ee (0/s il and 5as 3ell 6rilling and ervicing e1ool "ebsite for more information on safetyand health hazards at oil and gas etraction sites.

Ho# .an OSH and NIOSH Help*

OSH has compliance assistance specialists throughout the nation "ho can provide informationto employers and "orkers about (0 standards, short educational programs on speci*c hazards

or (0 rights and responsibilities, and information on additional compliance assistanceresources. Contact your local (0 oDce for more information.

OSH


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:eceive information and training %in a language and vocabulary they understand' about

"orkplace hazards, methods to prevent them, and the (0 standards that apply to their"orkplace.

:evie" records of "ork-related injuries and illnesses.

5et copies of test results that *nd and measure hazards.

9ile a complaint asking (0 to inspect their "orkplace if they believe there is a serious

hazard or that their employer is not follo"ing (0’s rules. (0 "ill keep all identitiescon*dential.

4ercise their rights under the la" "ithout retaliation or discrimination

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Hazard Alert - Exposure to Silica

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