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U.S. DEPARTMENT OF LABOR Occupational Safety and Health Administration

DIRECTIVE NUMBER: CPL 02-02-080 EFFECTIVE DATE: 06/25/2020

SUBJECT: Inspection Procedures for the Respirable Crystalline Silica Standards

ABSTRACT

Purpose: This Instruction establishes inspection procedures and enforcement 

policies for the Respirable Crystalline Silica Standards, 29 CFR § 

1910.1053 and 29 CFR § 1926.1153. 

Scope: This Instruction applies OSHA-wide.

References: Federal Register, 81 FR at 16285-16890, 29 CFR §§ 1910, 1915, 1926, 

Occupational Exposure to Respirable Crystalline Silica; Final Rule,

March 25, 2016.

OSHA Instruction, CPL 02-00-164 Field Operations Manual (FOM), 

April 14, 2020. 

OSHA Instruction CPL 02-00-158, Inspection Procedures for the 

Respiratory Protection Standard, June 26, 2014. 

OSHA Instruction CPL 02-02-079, Inspection Procedures for the Hazard 

Communication Standard (HCS 2012), July 9, 2015.

OSHA Instruction TED 01-00-015, OSHA Technical Manual (OTM)-

Section II: Sampling, Measurement Methods and Instruments, Chapters 1-

3, February 11, 2014.

OSHA Instruction ADM 04-00-003, OSHA Safety and Health 

Management System, May 6, 2020.

Cancellations: None.

State Impact: Notice of intent required. States are expected to have accessible 

enforcement policies and procedures in place which are at least as 

effective as those in this Instruction. 
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Action Offices: OSHA National, Regional and Area Offices, and On-Site Consultation 

Programs.

Originating Office: Directorate of Enforcement Programs

Contact: Office of Health Enforcement

Directorate of Enforcement Programs

200 Constitution Ave., NW, Room N-3119

Washington, DC 20210

(202) 693-2190 

By and Under the Authority of

LOREN SWEATT

Principal Deputy Assistant Secretary 
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Executive Summary

This new Instruction establishes OSHA’s field inspection and enforcement procedures designed 

to ensure uniformity when addressing respirable crystalline silica exposures in the workplace. 

These two new expanded health standards, general industry/maritime (29 CFR § 1910.1053) and 

construction (29 CFR § 1926.1153), were published in the Federal Register on March 25, 2016,

and became effective June 23, 2016.

The two new standards adopted a new permissible exposure limit (PEL) of 50 micrograms of 

respirable crystalline silica per cubic meter of air (μg/m3) as an 8-hour time-weighted average. 

Except as noted below, general industry and maritime employers had until June 23, 2018, to 

comply with the requirements of 29 CFR § 1910.1053.

Beginning on June 23, 2018, general industry and maritime employers must have offered

medical surveillance to employees who will be exposed above the PEL for 30 or more days a 

year. On June 23, 2020, this requirement expanded to include employees who would be exposed

at or above the 25 μg/m3 action level (AL) for 30 or more days a year. Additionally, the 

obligation to implement engineering controls to limit exposures in hydraulic fracturing 

operations in the oil and gas industry to the new PEL do not commence until June 23, 2021. 

Until that time, hydraulic fracturing employers must provide employees exposed to respirable 

crystalline silica in hydraulic fracturing operations with respiratory protection and ensure its use 

if employee exposures exceed the PEL.

Construction industry employers were scheduled to be in compliance with all the standard’s

provisions, except for methods of sample analysis in paragraph (d)(2)(v), by June 23, 2017. 

However, on April 6, 2017, OSHA extended the initial compliance date to September 23, 2017. 

The compliance date for the methods of sample analysis requirements in paragraph (d)(2)(v)

remain unchanged; as of June 23, 2018, construction industry employers must be in compliance 

with that provision.
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Table of Contents

Chapter Page

I. Purpose. ....................................................................................................................... 1

II. Scope. ........................................................................................................................... 1

III. References. .................................................................................................................. 1

IV. Cancellations. .............................................................................................................. 2

V. Action Offices. ............................................................................................................. 2

VI. Federal Program Change. ......................................................................................... 2

VII. Significant Changes. .................................................................................................. 2

VIII. Background. ............................................................................................................... 3

IX. Inspection Procedures. .............................................................................................. 4

A. Scope and Application. .......................................................................................... 4

B. Definitions. ............................................................................................................. 9

C. Permissible Exposure Limit (PEL). ...................................................................... 12

D. Exposure Assessment. .......................................................................................... 19

E. Table 1- Specified exposure control methods (29 CFR § 1926.1153). ............... 30

F. Regulated Areas (General Industry/Maritime only). ............................................ 44

G. Methods of Compliance........................................................................................ 47

H. Respiratory Protection. ........................................................................................ 60

I. Housekeeping Practices. ....................................................................................... 64

J. Medical Surveillance. .......................................................................................... 68

K. Communication of Hazards.. ............................................................................... 76

L. Recordkeeping. .................................................................................................... 79

M. Dates. ................................................................................................................... 86

X. Multi-Employer. . ..................................................................................................... 87

XI. Temporary Workers. ............................................................................................... 87

XII. Drafting OSHA Citations for RCS Violations. ..................................................... 92

XIII. Training for OSHA Personnel. ............................................................................... 92

XIV. Medical Examinations for OSHA Personnel. ........................................................ 93

XV. Protection of OSHA Personnel. .............................................................................. 93

XVI. OSHA Information System (OIS) Coding Instructions. ..................................... 94
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Appendix A. .............................................................................................................................. A-1

Appendix B. .............................................................................................................................. B-1

Appendix C. .............................................................................................................................. C-1

Appendix D. .............................................................................................................................. D-1

Appendix E. ...............................................................................................................................E-1

Appendix F. ..............................................................................................................................F-1

Appendix G. .............................................................................................................................. G-1

Appendix H. .............................................................................................................................. H-1
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I. Purpose.

The purpose of this Instruction is to provide guidelines and establish uniform inspection 

and enforcement procedures for the respirable crystalline silica standards. The two silica 

standards, 29 CFR § 1910.1053 (General Industry and Maritime) and 29 CFR § 

1926.1153 (Construction), published in the Federal Register/ Vol. 81 No. 58/ Friday 

March 25, 2016, became effective on June 23, 2016.

II. Scope.

This Instruction applies OSHA-wide.

III. References.

A. Federal Register, 81 FR at 16285-16890, 29 CFR §§ 1910, 1915, 1926, 

Occupational Exposure to Respirable Crystalline Silica; Final Rule March 25, 

2016. https://www.gpo.gov/fdsys/pkg/FR-2016-03-25/pdf/2016-04800.pdf.

B. OSHA Instruction CPL 02-00-164, Field Operations Manual (FOM), April 14, 

2020. https://www.osha.gov/enforcement/directives/cpl-02-00-164.

C. OSHA Instruction CPL 02-00-158, Inspection Procedures for the Respiratory 

Protection Standard, June 26, 2014. 

https://www.osha.gov/enforcement/directives/cpl-02-00-158.

D. OSHA Instruction CPL 02-02-079, Inspection Procedures for the Hazard 

Communication Standard (HCS 2012), July 9, 2015. 

https://www.osha.gov/enforcement/directives/cpl-02-02-079.

E. OSHA Instruction TED 01-00-015, OSHA Technical Manual―Section II: 

Sampling, Measurement Methods and Instruments, Chapters 1- 3, February 11, 

2014. https://www.osha.gov/dts/osta/otm/index.html.

[Note, some information in this document does not reflect OSHA's respirable 

crystalline silica rule published on March 25, 2016.]

F. OSHA Instruction CPL 02-02-072, Rules of agency practice and procedure 

concerning OSHA access to employee medical records, August 22, 2007.

https://www.osha.gov/enforcement/directives/cpl-02-02-072.

G. OSHA Frequently Asked Questions (FAQs) for Occupational Exposure to 

Respirable Crystalline Silica in General Industry/Maritime (GI FAQs) and 

Construction (CON FAQs).

https://www.osha.gov/dsg/topics/silicacrystalline/SilicaGeneralIndustryFAQs.pdf.

https://www.osha.gov/dsg/topics/silicacrystalline/SilicaConstructionFAQs.pdf.
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H. OSHA Instruction ADM 04-00-003, Safety and Health Management System,

May 6, 2020. 

https://www.osha.gov/enforcement/directives/adm-04-00-003.

IV. Cancellations. None.

V. Action Offices.

A. Responsible Office. Directorate of Enforcement Programs (DEP), Office of 

Health Enforcement (OHE). 

B. Action Offices. National, Regional and Area Offices, State Plan and State 

Consultation Offices.

C. Information Offices. OSHA National Office.

VI. Federal Program Change. 

Notice of Intent and Equivalency Required. This Instruction describes a federal program 

change that establishes policies and procedures necessary for the enforcement of the 

silica standards. State Plans are required to establish enforcement policies and 

procedures that are at least as effective as those in this Instruction and are available for 

review. Within 60 days of the date of issuance of this Instruction, State Plans must 

submit a notice of intent indicating if the State Plan will adopt policies and procedures 

identical to those in this Instruction or will adopt or maintain policies and procedures that 

are different from the federal program.

If the State Plan adopts or maintains policies and procedures that differ from the federal 

program, the State Plan must identify the differences and either post its policies and 

procedures on its website and provide a link to OSHA, or submit an electronic copy to 

OSHA with information on how the public may obtain a copy. State Plan adoption, 

either identical or different, shall be accomplished within 6 months. Documentation of 

State Plan adoption, and the date of adoption, must be provided to OSHA within 60 days 

of the date on which the State Plan adopts the new procedures or decides to maintain its 

own inspection procedures. If the State adopts identical policies and procedures, it must 

provide the date of adoption to OSHA within 60 days of the date of adoption.

OSHA will post summary information of the State Plan responses to this Instruction on 

its website (www.osha.gov).

VII. Significant Changes.

A. This Instruction outlines the changes in enforcement due to the publication of the 

silica standards in the Federal Register, 81 FR at 16285 (Mar. 25, 2016).

The silica standards establish a PEL of 50 μg/m3 and an action level (AL) of 25

μg/m3 for the three major forms of crystalline silica (i.e., quartz, cristobalite, and 
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tridymite1) for the general, maritime, and construction industries. 

B. The new PEL represents a change from the preceding PELs, which were based on 

formulas and were inconsistent between industries and forms of silica. This 

change is particularly significant with regard to the preceding PEL for the 

construction and shipyard industries, which was based on a particle count method, 

expressed in terms of millions of particles per cubic foot (mppcf), and required 

the use of a conversion factor to yield results reported in mg/m3.

VIII. Background.

The term “silica” refers broadly to the mineral compound silicon dioxide (SiO2), which

can be crystalline or amorphous in molecular structure. The silica standards apply only 

to crystalline silica―not amorphous silica. Quartz is the most common form of 

crystalline silica, and cristobalite is also sometimes encountered in the workplace (e.g., 

refractory bricks containing quartz can convert to cristobalite when subjected to 

prolonged high temperatures). The silica standards focus on the health effects related to 

the inhalation of respirable dust, which is generally defined as particles that are capable 

of reaching the gas-exchange region of the lung (i.e., particles less than 10 microns (μm) 

in aerodynamic diameter).

Exposure to crystalline forms of silica is associated with a number of health effects, 

including silicosis (an irreversible and potentially deadly lung disease), lung cancer, other 

non-malignant respiratory diseases (such as chronic bronchitis, emphysema, or chronic 

obstructive pulmonary disease), kidney disease, immunological effects, and activation of 

latent tuberculosis (TB) infections. Crystalline silica has been classified as a Group 1

carcinogen―Carcinogenic to Humans―by the International Agency for Research on 

Cancer (IARC) [IARC, 2012], https://monographs.iarc.fr. The National Toxicology 

Program (NTP) has also listed respirable crystalline silica as a known human carcinogen 

since 2000 [NTP, 2016], https://ntp.niehs.nih.gov/annualreport/2016. Appendix D of this 

Instruction provides further information on silica, including its sources and industrial

uses, as well as on the adverse health effects of silica exposure.

Occupational exposure to crystalline silica occurs in a variety of workplace settings, 

including mining, manufacturing, construction, and shipyards. Processes associated with 

high rates of silica exposure include sandblasting, sand-casting in foundry operations, 

tunneling, cement cutting and demolition of concrete, working with masonry, and cutting

and grinding of stone and artificial stone. 

Reducing and ultimately eliminating the workplace-related incidence of silicosis has been 

a primary goal of OSHA since its inception. In 1972, OSHA issued guidelines for 

conducting inspections in workplaces with significant crystalline silica exposure. In the 

early 1980s, OSHA placed a special emphasis on the prevention of silicosis in foundries, 

 

1 Tridymite is rarely found in nature and rarely reported in the workplace.
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and in 1996 OSHA implemented a Special Emphasis Program (SEP) to reduce the 

workplace incidence of silicosis. Twelve years later, on January 24, 2008, OSHA 

implemented a National Emphasis Program (NEP) to identify and reduce or eliminate the 

health hazards associated with occupational exposure to crystalline silica. Due to the new 

2016 standard, OSHA cancelled the 2008 NEP on October 26, 2017. A revised silica 

NEP was issued in FY 2020.

The two new silica standards, 29 CFR § 1910.1053 for general industry/maritime and 

§ 1926.1153 for construction, provide equivalent protection for workers, to the extent 

feasible, while taking into account the variety of work activities and anticipated 

exposures and conditions that occur in these industries.

IX. Inspection Procedures.

A. Scope and Application.

1. The silica standards, 29 CFR § 1910.1053 (for general industry/maritime) 

and 29 CFR § 1926.1153 (for construction), apply to all occupational 

exposures to respirable crystalline silica, with some limited exceptions. 

The silica standards do not cover exposure to amorphous forms of silica, 

such as silica gel. There are certain other exemptions and exclusions from 

these standards as noted in this Instruction.

2. The general industry/maritime standard applies to shipyard employment 

(29 CFR § 1915) through cross-reference in 29 CFR § 1915.1053). While 

OSHA does not anticipate silica exposure in marine terminals or 

longshoring operations, if there is exposure, 29 CFR § 1910.1053 is 

applicable through 29 CFR § 1917.1(a)(2)(xiii) and 29 CFR § 

1918.1(b)(9), respectively, which reference 29 CFR § 1910, Subpart Z. 

Therefore, compliance with the silica standard under 29 CFR § 1910.1053 

is required at marine terminals and longshoring facilities where silica 

exposure exists.

3. The general industry/maritime silica standard does not apply to 

construction as defined in 29 CFR § 1910.12(b).

4. The general industry/maritime silica standard does not apply to 

agricultural operations covered under 29 CFR Part 1928.

5. The general industry/maritime silica standard does not apply to exposures 

that result from processing of sorptive clays.

Note: Sorptive clays are a discreet subset of deposits found in certain 

regions of the U.S. that exists as either amorphous silica or as geologically 

ancient, occluded quartz. Although the silica standard does not apply to 

exposures that result from the processing, packaging, and distribution of 
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sorptive clays, 29 CFR § 1910.1000 Table Z-3, the preceding general 

industry PEL (i.e., the formula that is approximately equivalent to 100 

μg/m3) continues to apply to sorptive clay exposures. The PEL for 

sorptive clays should be calculated as specified in Table Z-3.

6. The silica standard also allows general industry and maritime employers to 

comply with the construction standard (29 CFR § 1926.1153), instead of 

the general industry and maritime silica standard, in certain circumstances. 

Specifically, 29 CFR § 1910.1053 does not apply to general industry and 

maritime employers if all the following conditions are met:

a. The employer complies with all applicable provisions of the 

construction standard (29 CFR § 1926.1153).

• For example, the employer must comply with requirements in 

29 CFR § 1926.1153(g) to designate a competent person to 

implement the written exposure control plan. 

b. The task performed is indistinguishable from a construction task 

listed on Table 1-Specified Exposure Control Methods

(29 CFR § 1926.1153(c)).

• Indistinguishable tasks are those performed primarily during 

maintenance and repair activities in general industry or maritime 

settings, and involve a task described in the construction standard’s 

Table 1. These tasks must be of the same nature and type as those 

in construction.

o An example of an indistinguishable task is using a handheld 

drill during repair or maintenance of existing power delivery 

lines, which is considered a general industry task. This task is 

indistinguishable from using a handheld drill during the 

installation of new power delivery lines, which is a 

construction task. 

c. The task will not be performed regularly in the same environment 

and conditions. This exception is intended for situations where the 

tasks will be performed in different environments and conditions, 

rather than in a stable and predictable environment.

• For example, an employer whose business includes chipping out 

concrete from inside the drums of ready-mixed concrete trucks 

using pneumatic chipping tools would be engaged in a task that 

will be regularly performed in a relatively stable and predictable 

environment. Such activity is not covered by Table 1, which is 

intended in part to accommodate situations where the tasks will be 
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performed in different environments and conditions. Another 

example is the sanding or cutting of concrete blocks in a concrete 

block manufacturing plant because the task is performed regularly 

in the same environment and conditions.

Note 1: This exemption applies by task. In other words, an employer who 

is following the construction standard for a task that meets the criteria 

described above (Sections IX.A. 6a, b, and c) must continue to follow the 

standard for general industry and maritime for other tasks covered under 

the standard unless the other tasks also meet the criteria. 

Note 2: If the employer fails to comply with an applicable provision, 

including meeting the criteria described in above Sections IX.A. 6a, b, and 

c, the exemption does not apply. If an employer claims this exception,

CSHOs should evaluate the standard’s three key conditions as stated in 

this section (Section IX.A.6). If the employer fails to meet any of these 

conditions, the CSHO should refer to the general industry/maritime 

standard (29 CFR § 1910.1053) and cite the employer for any violations of 

that standard. 

7. The standard for general industry and maritime does not apply where the 

employer has objective data demonstrating that employee exposures to 

respirable crystalline silica will remain below 25 μg/m3 as an 8-hour timeweighted average (TWA) under any foreseeable conditions (see GI FAQ

#1).

Note 1: The exception related to employee exposure levels is based on 

total respirable crystalline silica exposures from all sources and must take 

into account all conditions that may add or contribute to the employee’s 

overall exposure level.

a. Where an employer claims exclusion from the standard on the

basis of objective data, the data must meet the following criteria: 

o Demonstrate employee exposure to respirable crystalline silica 

associated with a particular product or material or a specific 

process, task, or activity on which the objective data were 

based and 

o Reflect workplace conditions closely resembling or with a 

higher exposure potential than the processes, types of material, 

control methods, work practices, and environmental conditions 

in the employer's current operations.

• The data must demonstrate that employee exposure will remain 

below 25 μg/m3 as an 8-hour TWA under any foreseeable 
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conditions.

• The data must be sufficient to accurately characterize employee 

exposures to respirable crystalline silica. See Section IX. B.4, for 

the discussion on objective data, and Sections IX.D.2 and IX.D 3, 

for inspection and citation guidelines for air sampling and 

exposure assessments. 

Note 2: For more information on the definition of objective data, see

29 CFR § 1910.1053(b) and Section IX. B.4.

b. The term "closely resembling" refers to circumstances where the 

major workplace conditions (e.g., processes, materials, control 

methods, work practices, and environmental conditions) which 

have contributed to the levels of historical exposure are no more 

protective than in the current workplace. OSHA’s intent is to 

allow data reflecting past exposures to be used to predict current 

exposures only when the conditions of the earlier job were not 

more protective (e.g., it would not be acceptable to use data 

obtained from a task performed outdoors to assess exposures when 

the task is performed indoors).

c. The phrase “any foreseeable conditions” means situations that can 

reasonably be anticipated. Because OSHA considers the potential

failure of most controls to be a foreseeable condition, the exception 

applies only where exposures below 25 μg/m3 as an 8-hour TWA 

are expected or achieved without the use of controls.

• For example, if an employer controls employee silica exposures 

using an engineering control such as local exhaust ventilation or a 

conveyor containment system, the potential failure of those 

controls is a foreseeable condition, and the employer will not be 

exempt from the standard on the basis of data showing that 

exposures are below 25 μg/m3 as an 8-hour TWA when the 

ventilation or containment system is used. 

o Employers need not account for the potential failure of 

some types of controls (e.g., substitution of non-silicacontaining materials for materials that contain silica, fixed 

walls that are a permanent part of a building’s structure) 

when it is not a foreseeable condition when determining 

whether employee exposure to silica will remain below 25 

μg/m3 calculated as an 8-hour TWA under any foreseeable 

conditions.

o Employers need not account for the potential failure of 
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measures that may contribute, in a limited fashion, to 

reducing silica exposures, but that are not adopted for that 

specific purpose (i.e., general building ventilation or 

heating, ventilation, and air conditioning (HVAC)

systems). 

8. The construction standard does not apply where employee exposure will 

remain below 25 μg/m3 as an 8-hour TWA under any foreseeable 

conditions (including the malfunction or failure of engineering controls 

implemented to reduce exposures to respirable crystalline silica). 

a. In general, OSHA anticipates employee exposure would be 25 

μg/m3 or greater when performing any of the tasks on Table 1, 

abrasive blasting, and tunnel boring, except under the conditions in 

(b).

b. The following tasks, when performed in isolation from other silicagenerating tasks, do not typically generate silica at or above 25 

μg/m3 as an 8-hour TWA under any foreseeable conditions: mixing 

small amounts of mortar; mixing bagged drywall compound that 

contains crystalline silica only as a trace contaminant; mixing 

bagged exterior insulation finishing system base and finish coat; 

removing concrete formwork; using block or tile splitters; using 

manual (i.e., non-powered) chisels, shears, and utility knives; and 

pouring concrete footers, slab foundation, and foundation walls

(see CON FAQ #1).

Note: Exposures could exceed 25 μg/m3 as an 8-hr TWA in situations 

where employees are working with drywall or sanding joint compound for 

long periods of time in very dusty conditions. Although exposures to 

respirable crystalline silica may be low during drywall finishing when 

trace amounts of crystalline silica content joint compound is used, CSHOs 

should be aware of the potential for exposures to exceed the PEL for 

particulates not otherwise regulated (PNOR) (see 29 CFR § 1926.55). 

Sample these operations when appropriate.

c. In many cases, tasks performed for very short periods of time, in 

isolation from activities that generate significant exposure to silica,

will result in exposures below 25 μg/m3 as an 8-hour TWA under 

any foreseeable conditions (see CON FAQ #2).

d. In determining whether short-term tasks will result in exposures 

below 25 μg/m3 as an 8-hour TWA under any foreseeable 

conditions, take into account the following:

• An individual employee’s exposures to respirable crystalline silica 
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from all sources;

• All conditions that may add or contribute to the employee’s overall 

exposure levels (e.g., enclosed spaces); and,

• If the employee is engaged in a combination of short-term 

construction tasks that collectively result in a longer duration of 

exposure, which could exceed 25 μg/m3.

e. The construction standard does not require the employer to have 

objective data demonstrating that employee exposure to respirable 

crystalline silica will remain below 25 μg/m3 as an 8-hour TWA 

under any foreseeable conditions to support the exception.

B. Definitions.

Terms used in the preamble and regulatory text of the Silica standards:

1. Action level (AL) means a concentration of airborne respirable crystalline 

silica of 25 μg/m3, calculated as an 8-hour TWA. 

Note: Employee exposure at or above the AL under any foreseeable 

conditions triggers applicability of the construction and general 

industry/maritime standards. In general industry and maritime employers 

must assess the exposure of each employee who is or may reasonably be 

expected to be exposed at or above the AL. Additionally, beginning June 

23, 2020, the medical surveillance requirement in the general 

industry/maritime standard (but not the construction standard) is triggered 

by employee exposures at or above the AL for 30 or more days per year.

2. Air monitoring data refers to any air monitoring conducted by the 

employer to comply with the requirements of the silica standard, including

compliance with the prescribed accuracy and confidence requirements (see

29 CFR § 1910.1053(d)(5) and 29 CFR § 1926.1153(d)(2)(v), and

Appendix A of the silica standards) (see GI FAQ #8).

3. Competent person means an individual who is capable of identifying 

existing and foreseeable respirable crystalline silica hazards in the 

workplace and who has the authority to take prompt corrective measures 

to eliminate or minimize them. The competent person must have the 

knowledge and ability necessary to fulfill the responsibilities set forth in 

Section 1926.1153(g) (e.g., make frequent and regular inspections of job 

sites, materials, and equipment to implement the written exposure control 

plan (ECP)). A competent person is not required under the Silica standard 

for general industry/maritime.

a. The employer can designate any employee to be a competent
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person if the employee has the necessary capabilities (whether 

acquired through training, education or work experience.)

b. An employee (including one who participates in silica-generating 

tasks on a job) could be designated as a competent person if he/she

can properly implement the employer’s written ECP (i.e., knows

the tasks involving silica exposure; the engineering controls, work 

practices, and respiratory protection needed to limit exposure; 

procedures used to restrict access, where necessary), and has 

authority to take prompt corrective measures to implement the

ECP.

c. Competent person training is performance-based. The employer is 

responsible for ensuring the competent person has the knowledge 

and ability to implement the written ECP (see CON FAQs #6, 37,

and 38). The training needed will depend on the types of work 

done. In some cases, successfully completing training required 

under the Silica standard and OSHA’s Hazard Communication 

Standard (HCS), 29 CFR § 1910.1200, may be enough (e.g., for 

small construction companies that perform limited silicagenerating tasks). In other cases, additional training may be 

needed, but that would vary among construction companies. For 

more information on training requirements for a competent person 

(see Section IX G.7 and G.8 of this Instruction and 81 FR at 

16811).

4. Objective data means information, such as air monitoring data from 

industry-wide surveys or calculations based on the composition of a 

substance, demonstrating employee exposure to respirable crystalline 

silica associated with a particular product or material or a specific process, 

task, or activity. The data must reflect workplace conditions closely 

resembling or with a higher exposure potential than the processes, types of 

material, control methods, work practices, and environmental conditions 

in the employer’s current operations. See 29 CFR § 1910.1053(b) and 29 

CFR § 1926.1153(b).

a. Types of data and exposure assessment strategies that may qualify 

as objective data include (see GI FAQ #8 and CON FAQ #19): 

• Data from industry-wide surveys;

• Data provided by equipment manufacturers;

• Data provided by trade or professional associations;

• Exposure mapping (determining exposures associated with 
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particular locations based on information obtained from sources 

that may include personal samples, area samples, and directreading instruments), (see GI FAQ #11);

• Calculations based on the composition of a substance; 

• Calculations based on the chemical and physical properties of a 

substance (in those instances where a substance’s physical and 

chemical properties demonstrate employee exposure to silica 

associated with a particular product or material or a specific 

process, task, or activity); and

• The employer’s historical air monitoring data, including data 

obtained prior to the effective date of the standard.

Note: The silica standards do not limit when objective data can be used to 

characterize exposure. OSHA notes that the same types of objective data 

that can be used to assess employee exposures under the performance 

option may be used to demonstrate that employee exposure to silica will 

remain below the AL of 25 μg/m3 calculated as an 8-hour TWA under any 

foreseeable conditions for purposes of ascertaining coverage under 

29 CFR § 1910.1053(a)(2) (see GI FAQ #8).

To ensure adequate employee protection, the objective data can be used to 

represent current exposures only when the conditions under which the 

objective data was gathered were not more protective (i.e., it would not be 

acceptable to use objective data obtained from a task performed outdoors 

to assess exposures when the task is performed indoors). Refer to the 

above definition of objective data to determine whether the employer 

accurately characterized employee exposure. 

An employer using the performance option can use data reflecting 

conditions that are standard across an industry to assess exposures of 

employees at individual facilities provided that the requirements in the 

standard are met (see GI FAQ #14).

5. Permissible exposure limit (PEL) means an airborne concentration of 

respirable crystalline silica of 50 μg/m3, calculated as an 8-hour TWA.

6. Physician or other licensed healthcare professional (PLHCP) means an 

individual whose legally permitted scope of practice (i.e., license, 

registration, or certification) allows him or her to independently provide or 

be delegated the responsibility to provide some or all of the particular 

health care services required by 29 CFR § 1910.1053(i) and 29 CFR § 

1926.1153(h).
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Note: A PLHCP can conduct medical examinations and procedures 

required under the Silica standards when he or she is licensed, registered, 

or certified by their respective state law to do so. Licensing and scope of 

practice definitions may vary from state to state. Questions regarding 

PLHCPs and their scope of practice may be directed to the Office of 

Occupational Medicine and Nursing (OOMN) in the National Office.

7. Regulated area means an area, demarcated by the employer, where an 

employee's exposure to airborne concentrations of respirable crystalline 

silica exceeds, or can reasonably be expected to exceed, the PEL.

8. Respirable crystalline silica means quartz, cristobalite, and/or tridymite 

contained in airborne particles that are determined to be respirable by a 

sampling device designed to meet the characteristics for respirableparticle-size-selective samplers specified in the International Organization 

for Standardization (ISO) 7708:1995: Air Quality―Particle Size Fraction 

Definitions for Health-Related Sampling. 

9. Specialist means an American Board Certified Specialist in Pulmonary 

Disease or an American Board Certified Specialist in Occupational

Medicine.

10. All other definitions in the standard are for terms previously used by 

OSHA in other health standards, and the terms are similarly defined and 

used in the new Silica standards. These terms include “Assistant 

Secretary,” “Director,” “employee exposure,” and “high-efficiency 

particulate air (HEPA) filter.” 

C. Permissible Exposure Limit (PEL).

1. General Information. 29 CFR § 1910.1053(c) and 29 CFR § 

1926.1153(d)(1) establish a PEL of 50 μg/m3 as an 8-hour TWA. 

Employers must ensure that no employee is exposed to an airborne 

concentration of respirable crystalline silica above that PEL. 

• An AL of 25 μg/m3 is also established for both standards

(29 CFR § 1910.1053(b) and 29 CFR § 1926.1153(b)).

Note: Employers that have fully and properly implemented the 

engineering controls, work practices, and respiratory protection for each 

employee performing a task listed in Table 1 of the construction standard 

(29 CFR § 1926.1153(c)) do not need to comply with the requirements of 

29 CFR § 1926.1153(d), including the PEL.

2. Inspection Guidelines.
13

a. CSHOs should be prepared to collect personal breathing zone 

samples on the first day of the inspection, whenever possible. 

When sampling is conducted, collect personal samples to measure 

the 8-hour TWA for the silica operations likely to exceed the PEL, 

in accordance with the OSHA Technical Manual (OTM) (TED 01-

00-015), Section II, Chapter 1, and OSHA sampling method ID142.

• Ensure that samples are collected in the employee’s breathing zone 

(i.e., in a hemisphere forward of the shoulders within a radius of 

approximately six to nine inches).

• Based on the specific situation or conditions observed, use 

discretion to determine whether to sample for a full shift.

• If CSHOs determine that full-shift sampling is not necessary, 

document this in the case file.

• If an air sampling filter becomes overloaded with dusts or other air 

contaminants while sampling, the result will not be valid. To 

avoid this situation where high loading of the filter is likely (such 

as when sampling abrasive blasting operations or grinding tasks), 

the exposure monitoring should be conducted using consecutive air 

samples over shorter sampling periods.

• When sampling “dusty” operations, such as abrasive blasting 

operations or grinding tasks, periodically inspect the sampling 

apparatus. If a sampling pump begins to sound different because 

of heavy loading of the filter, or if the filter appears fully brown or 

gray with particulates, then the sampling cassette should be 

replaced. Such overloading may occur in as short a time as 30 

minutes or within a few hours depending on the operation. 

• If the operations/processes are not active during the course of the 

inspection, as appropriate, CSHOs should request from the 

employer the next available time the process(es) will resume and 

return to monitor.

Note: Refer to Appendix B of this Instruction for more detailed 

instructions for collecting air samples.

b. Review the employer’s written ECP to determine which workplace 

tasks involve exposure to respirable crystalline silica and the

engineering controls and work practices the employer planned to 

implement to limit employee exposures during each listed task.
14

c. Review the employer’s exposure records or other data the 

employer used to assess exposures to determine what exposure 

levels might be expected before entering the work area:

• If the employer’s air monitoring records indicate overexposures, 

obtain copies of the employer’s exposure data for the case file;

• Any other related attachments or separate documents, such as 

laboratory analytical results or chain of custody sample forms, 

should also be placed into the case file. 

• Collect samples if the employer has not assessed exposure, if the 

employer’s assessment indicates exposures could exceed the PEL, 

or if the employer’s assessment may not be representative (e.g., 

new or different operations are occurring in the workplace that do 

not closely resemble the operations represented by the employer’s 

exposure data). 

d. Construction employers that have not fully and properly 

implemented Table 1 (or are performing a task or using equipment 

not listed on Table 1) must comply with § 1926.1153(d), and the 

guidelines in this section should be followed to assess compliance

with the PEL. 

• The following guidance applies when employees perform both 

Table 1 and non-Table 1 tasks: 

o Where the employer is fully and properly implementing the 

specified controls for Table 1 tasks, the CSHO does not need to 

collect personal air samples for those tasks.

o Where the employer is not fully and properly implementing the 

specified controls for Table 1 tasks, the CSHO should sample 

one or more employees engaged in those tasks, as necessary.

o Where the same employee is performing Table 1 tasks and also 

non-Table 1 tasks but the employer has not fully and properly 

implemented the specified controls, the CSHO should sample 

if exposures from the combined tasks are likely to exceed the 

PEL.

o Where an employee is performing non-Table 1 tasks, the 

CSHO should collect samples for the non-Table 1 

tasks/operations that are likely to result in exposures over the 

PEL.
15

Note: Some examples of silica-generating tools/tasks not on Table 1 

include: reciprocating cutting tools, concrete chain saws, wire saws, 

abrasive blasting and tunnel boring.

o Where sampling two or more tasks, CSHOs should collect fullshift personal samples and document the amount of time spent 

in each of the separate tasks/operations.

Note: CSHOs should consult with the Salt Lake Technical Center if there 

is a need for guidance.

• If an overexposure is found and it appears that the employer was 

using appropriate engineering controls and work practices, then to 

the extent feasible: 

o CSHOs should evaluate the employer’s respiratory protection 

program. Any deficiencies should be addressed in accordance 

with Section IX.H (Respiratory Protection) of this Instruction;

o Where the CSHO documents an employee exposure exceeding 

the PEL, but all feasible engineering and work practice controls 

were instituted and all required appropriate personal protective 

equipment was provided, a violation of the PEL may not be 

cited. Examples of circumstances where this might be 

expected include work done in confined spaces or within an 

abrasive blasting containment area or enclosure. The CSHO’s 

assessment of feasibility must be made on a case-by-case basis.

Note: See also OSHA Letter, Use of feasible engineering/work practice 

controls for exposure to hexavalent chromium, (Cr(VI)) for welding in 

confined spaces; housekeeping and disposal of large/bulky waste 

materials, May 31, 2007.

• If CSHOs must enter a regulated area or other areas where 

anticipated exposures are above the PEL, they should discuss the 

need with their Area Director (AD) or supervisor prior to entering 

a regulated area. The CSHO must wear the personal protective 

equipment (PPE) and clothing required by the employer or as 

appropriate for the CSHO’s inspection or sampling activity. 

However, CSHOs must be conservative about time spent in areas 

where high concentrations exist or are suspected. 

e. When sampling employee exposures, CSHOs should:

• Select a suitable remote location from which to view the operation 

or frequent the work areas often enough to keep the sampling 
16

under surveillance; and

• Review Sections XIII - XV of this Instruction for specific policies 

and precautions to minimize exposures of OSHA personnel.

3. Variability in sampling. There may be differences in exposures that may

occur due to workplace conditions such as fluctuations in environmental 

conditions or air movement. For additional information see the OTM at: 

https://www.osha.gov/dts/osta/otm/otm_toc.html. 

a. If a CSHO obtains a sample showing exposures above the PEL but 

believes, based on the employer’s exposure data, that the results 

may be due to unpreventable exposure variability, the AD may 

consider whether to conduct a follow-up inspection in lieu of 

issuing a citation. The CSHO will compare both sets of exposure 

data to determine whether the employer’s data are representative. 

The evaluation shall:

• Review the employer’s long-term body of data to determine their 

documented exposure pattern; and,

• Review whether the employer’s records were obtained for 

tasks/operations that are representative of those under OSHA’s 

evaluation.

b. The employer has the burden to demonstrate that the CSHO's 

samples are not representative of normal exposure levels. To meet 

its burden, the employer must: 

• Provide data consisting of a series of full-shift measurements 

representative of the exposure of the employee(s) under 

consideration (e.g., related to specific job activity or tasks); 

• Demonstrate that the measurements were taken within the last 

year; and,

• Show that random fluctuations in the TWA exposures above the 

PEL occur due to circumstances beyond the control of the 

employer (e.g., environmental conditions or air movement);

c. After reviewing the employer’s sampling/documentation, the 

CSHO should confer with the AD or Assistant Area Director 

(AAD) regarding the existence (or not) of a violation and whether 

it is necessary to re-sample or re-inspect at a later date (see 81 FR 

at 16757).
17

In general, re-sampling is rarely necessary. The employer is 

responsible for demonstrating that the CSHO’s one-day sample is 

not representative of normal exposure levels.

d. If the CSHO is not able to re-inspect/resample (e.g., at a 

construction site or the operation ceased), then the CSHO and AD 

should consider the following factors before determining whether a 

citation should be issued:

• Whether compliance with the PEL can be achieved (based on air 

monitoring data and/or objective data) in the task/operation for the 

majority of time that the work is performed (e.g., exposures above 

the PEL would be rare occurrences);

• Whether the employer was appropriately maintaining and/or 

monitoring feasible engineering controls and ensuring adherence to

work practice controls; and,

• If the employer’s previous exposure monitoring records adequately 

demonstrate the exposure pattern for tasks/operations that are 

representative of those under OSHA’s evaluation.

4. Citation Guidelines. Citations for violations of the PEL should be issued 

as follows: 

a. For general industry/maritime employers:

• If samples collected show employee exposure above the PEL of 50 

μg/m3, cite 29 CFR § 1910.1053(c). For citations involving 

failures to properly implement engineering and work practice 

controls and require use of respiratory protection follow citation 

procedures for combining and grouping violations in CPL 02-00-

164. Where appropriate, 29 CFR § 1910.1053(f)(1) should be 

cited and grouped with 29 CFR § 1910.1053(c) and any applicable 

subparagraphs of 29 CFR § 1910.1053(g).

• If samples collected show that employees are exposed to respirable 

crystalline silica over the PEL of 50 μg/m3, but the employer has 

instituted all feasible engineering and work practice controls and 

employees are adequately protected by an effective respiratory 

protection program, then there is no PEL violation. 

Note: Hydraulic fracturing operations in the oil and gas industry have 

until June 23, 2021, to implement feasible engineering controls to achieve 

the PEL. See Appendix G of this Instruction for guidance on hydraulic 

fracturing inspections. 
18

b. For construction employers:

• Where the employer has fully and properly implemented the 

engineering controls, work practices, and respiratory protection 

specified on Table 1, then there is no PEL violation;

• Where the employer has not fully and properly implemented the 

engineering controls, work practices, and respiratory protection 

specified on Table 1 and sampling shows exposure over the PEL, 

the CSHO should cite § 1926.1153(c)(1) and paragraph (d)(1) as 

grouped violations;

• Where sampling shows an overexposure for tasks not on Table 1 

and the employer has not instituted all feasible engineering and 

work practice controls or adequately protected employees by an 

effective respiratory protection program, then the CSHO should 

cite the overexposure as a violation of 29 CFR § 1926.1153(d)(1);

Deficiencies in any of the requirements for engineering and work 

practice controls and respiratory protection (29 CFR § 1910.134) 

should be cited in accordance with the citation procedures for 

combining and grouping violations in the current FOM. Where 

appropriate, 29 CFR § 1926.1153(d)(3) and paragraph (e) should 

also be grouped with the violation related to the overexposure.

c. For both construction and general industry/maritime employers:

• If the CSHO obtains a sample showing exposures above the PEL 

but has reason to think, based on the employer’s exposure data, 

that the results may be due to unpreventable exposure variability, 

then the AD may consider whether to conduct a follow-up 

inspection in lieu of issuing a citation. For more information about 

how to proceed in such situations, refer to the variability in 

sampling guidance in Section IX. C.3.

• Area Offices (AO) will use OSHA’s standard practice of 

accounting for sampling and analytical error providing a margin of 

error above the PEL before OSHA issues a citation for violating 

the PEL.

• A violation is established if the measured exposure exceeds the 

PEL after applying sampling and analytical error (SAE) 

corrections and applying a 95 percent limit (refer to SAE 

instructions in the OTM, TED 01-00-015). Document silica 

exposures by ensuring that all available exposure data whether 
19

provided by the employer or obtained during the inspection are 

copied to the case file.

5. Follow-up Inspections.

a. To determine whether the employer has eliminated hazards or 

reduced exposures below the PEL, follow-up inspections are

conducted in accordance with the FOM Chapter 3, VII.K based on 

available resources. Where exposures could not feasibly be 

reduced to or below the PEL, engineering controls and work 

practice controls should still be implemented to reduce exposures 

to the extent feasible, and workers provided with adequate 

respiratory protection.

b. For those employers where follow-ups cannot be performed (e.g., 

certain construction sites or temporary abrasive blasting 

operations), the AO should ask the employer to provide written 

updates to document the progress of the abatement efforts, in 

accordance with 29 CFR § 1903.19.

c. A follow-up inspection is not required when the AO has specific 

knowledge and documentation indicating that the employer is no 

longer using respirable crystalline silica or there are no workers 

exposed to respirable crystalline silica.

D. Exposure Assessment.

An exposure assessment is required so that the employer can select the proper 

control methods to be used and evaluate the effectiveness of those selected 

methods. 

29 CFR § 1910.1053(d)(1) and 29 CFR § 1926.1153(d)(2)(i) require employers to 

assess the exposure of each employee who is, or may reasonably be expected to 

be, exposed to respirable crystalline silica at or above the AL using either a 

performance option or a scheduled monitoring option. 

Note: In construction, employers that fully and properly implement the 

engineering controls, work practices, and respiratory protection as specified on

Table 1 do not have to assess the exposure of employees engaged in the task, and 

the following guidance in this section does not apply.

29 CFR § 1910.1053(d)(4) and 29 CFR § 1926.1153(d)(2)(iv) require 

reassessment whenever there is a change in the production, process, control 

equipment, personnel, or work practices that may reasonably be expected to result 

in new or additional exposures at or above the AL, or when the employer has any 

reason to believe that new or additional exposures at or above the AL may have 

occurred. 
20

1. Assessment options. Employers have two options for assessing the

exposure of employees: a) the performance option (29 CFR § 1910 

1053(d)(2) or 29 CFR § 1926.1153(d)(2)(ii)), or b) the scheduled 

monitoring option (29 CFR § 1910.1053(d)(3) or 29 CFR § 

1926.1153(d)(2)(iii)).

Note: An employer may use a combination of these two exposure 

assessment approaches in a single facility as long as the employer ensures 

that each employee’s exposure is adequately assessed. For each individual 

employee, the employer may choose to use either the performance option 

or the scheduled monitoring option (see GI FAQs #6 and #7 and CON 

FAQs #19 and #20).

a. Performance Option. This option allows the employer some 

flexibility to assess the 8-hour TWA exposure of each employee on 

the basis of any combination of air monitoring data or objective 

data sufficient to accurately characterize each employee’s exposure 

to respirable crystalline silica. The employer is responsible for 

ensuring that the data accurately characterizes employee exposure.

Note 1: See definition section for further guidance on use of objective 

data.

Employers choosing the performance option must:

• Assess exposures before work commences and continue to 

reassess, as warranted (see GI FAQ #15);

• Ensure that employee exposures have been accurately

characterized and that the data reflects each shift, each job 

classification, and each work area; and,

• Comply with the remaining exposure assessment provisions, where 

applicable (i.e., reassessment of exposures, methods of sample 

analysis for air monitoring, employee notification of assessment 

results, and observation of monitoring, per 29 CFR §§

1910.1053(d)(4)-(7) and 29 CFR § 1926.1153(d)(2)(iv)-(vii), 

respectively). 

In addition:

• Employers may characterize employee exposure within a range to 

account for variability in exposure (e.g., employee exposure is 

between the AL and the PEL) and may also use this option to show 

that exposures exceed the PEL by a certain level (such as less than 
21

10 times the PEL) after using all feasible controls. The employer 

would then know the minimum assigned protection factor (APF)

necessary (in this example, respiratory protection with an APF of 

at least 10) (see GI FAQ #9);

• Historical air monitoring data, including monitoring data obtained 

prior to the standards’ effective dates, may qualify as objective 

data to characterize employee exposures. However, the employer 

has to ensure the data reflect workplace conditions (e.g., processes, 

types of material, control methods, work practices) and 

environmental conditions closely resembling or with a higher 

exposure potential than those in the employer’s current operations 

(see GI FAQ #10);

• OSHA permits employers to rely on objective data even where 

exposures reflected in the data may exceed the AL or PEL. This

provides employers with flexibility to assess employee exposures

to respirable crystalline silica, and to ensure that the data used are 

accurate in characterizing employee exposures.

Note 2: Objective data, such as historical monitoring data, reflecting 

“worst case” conditions is helpful in characterizing employee exposure.

• An employer could determine that there are no differences between 

the exposures of two employees in a certain job classification who 

perform the same task on different shifts. In this case,

the employer could characterize the exposure of the second 

employee based on the characterization of the first employee’s 

exposure.

• While there is no set schedule for reassessment of exposures under 

the performance option, employers have an ongoing duty to 

accurately characterize employee exposure. Under 29 CFR § 

1910.1053(d)(4) and 29 CFR § 1926.1153(d)(2)(iv), an employer

must reassess exposures whenever a change in the production, 

process, control equipment, personnel, or work practices may 

reasonably be expected to result in new or additional exposures at 

or above the AL or when the employer has any reason to believe 

that new or additional exposures at or above the AL have occurred.

b. Scheduled Monitoring Option. This option requires that employers

perform initial monitoring and follow-up monitoring at specific 

intervals based on monitoring results. See 29 CFR §

1910.1053(d)(3) and 29 CFR § 1926.1153(d)(2)(iii). Monitoring 

must assess the 8-hour TWA exposure for each employee on the 

basis of one or more personal breathing zone air samples reflecting
22

the exposures of employees on each shift and in each job

classification and work area.

Employers following the scheduled monitoring option must do the 

following:

• Conduct initial monitoring as soon as work begins so that they are 

aware of exposure levels and where control measures are needed; 

and,

• Where several employees perform the same job tasks on the same 

shift and in the same work area, employers may sample a 

representative number of employees. Representative sampling

involves monitoring the employee(s) reasonably expected to have 

the highest exposure to respirable crystalline silica. This exposure 

is then assigned to the other employees in the group who perform 

the same tasks on the same shift and in the same work area (see GI 

FAQ #17).

Sample results:

• Results may be used to represent several employees who perform 

similar work with silica exposures of similar duration and 

magnitude:

o For example, monitoring results of the respirable crystalline 

silica exposure of the employee closest to an exposure source 

may also be attributed to other employees who are similarly 

exposed.

• If initial monitoring measures exposures below the AL of 25 

μg/m3, the employer may discontinue monitoring for employees

whose results are represented by that monitoring (in accordance 

with 29 CFR § 1910.1053(d)(3)(ii) and 29 CFR § 

1926.1153(d)(2)(iii)(B));

• If the most recent exposure monitoring indicates exposures are at 

or above the AL, but at or below the PEL, the employer must

repeat monitoring every six months (in accordance with

29 CFR § 1910.1053(d)(3)(iii) and 29 CFR § 

1926.1153(d)(2)(iii)(C));

• If the most recent exposure monitoring indicates exposures are 

above the PEL, the employer must repeat monitoring every three 

months (in accordance with 29 CFR § 1910.1053(d)(3)(iv) and 

29 CFR § 1926.1153(d)(2)(iii)(D)); and,
23

• Where the most recent (non-initial) monitoring indicates that 

employee exposures have dropped below the AL, monitoring must 

be repeated within six months until two consecutive 

measurements, taken seven or more days apart, are below the AL. 

At that time, the employer may discontinue monitoring for those 

employees whose exposures are represented by such monitoring, 

except as otherwise provided in 29 CFR § 1910.1053(d)(4) and 29 

CFR § 1926.1153(d)(2)(iv) (in accordance with 29 CFR § 

1910.1053(d)(3)(v) and 29 CFR § 1926.1153(d)(2)(iii)(E)).

Note: Following the initial monitoring, construction employers can 

continue to perform scheduled monitoring at the frequency specified in the 

standard in new work areas, provided that the task and the workplace 

conditions in new work areas are substantially similar to tasks and 

conditions at the time of initial monitoring (i.e., they are not reasonably 

expected to result in exposures above those detected during the most 

recent monitoring. (29 CFR §1926.1153(d)(2)(iii) and paragraph 

(d)(2)(iv)) (see CON FAQ #21).

c. Switching Between Exposure Assessment Options. An employer 

may switch from the scheduled monitoring option to the 

performance option, and may use air monitoring data generated 

during repeated scheduled monitoring as objective data under the 

performance option, provided the data are sufficient to accurately 

characterize employee exposures. This may be useful in certain 

workplaces (e.g., for silica operations that are intermittent, 

variable, and of short duration) or in silica operations where 

conditions do not normally change and periodic monitoring would 

provide little information and no added protection for employees 

(e.g., abrasive blasting operations that greatly and consistently 

exceed the PEL).

2. Inspection Guidelines.

a. CSHOs should review all air monitoring and/or objective data the 

employer relied on to assess employee exposure to determine 

whether the employer has accurately characterized the employees’ 

exposures. CSHOs should verify that the employer’s assessment

was conducted in accordance with either the performance option or 

the scheduled monitoring option, as outlined above in Sections IX.

D.1.a or b (Exposure Assessment) of this Instruction:

• If an employer has not conducted an exposure assessment for any 

employee working in conditions the CSHO believes are reasonably 

likely to result in exposures at or above the AL, the CSHO should 
24

conduct personal sampling. In the event sampling cannot be 

conducted, other evidence should be considered in order to 

establish that an employee’s exposure is reasonably expected to be 

at or above the AL. For example, the CSHO could review the 

employer’s written exposure control plan, data provided by the 

equipment manufacturer or trade/professional associations, and 

exposure data for the relevant task from the rulemaking record. 

The CSHO should also gather evidence regarding all potential 

silica-generating tasks/sources and duration of employee 

exposure(s);

• If there is any uncertainty regarding the accuracy of the employer’s 

exposure assessment, the CSHO should conduct personal 

sampling. Refer to the previous guidance on air sampling under 

Section IX. C, Permissible Exposure Limit;

• CSHOs should be aware that for all industries multiple 

operations/tasks occurring at the same time in the same area may 

result in higher worker exposures than those found during 

individual operations/tasks; and,

• If there is uncertainty about whether an employer’s sample times 

were representative, CSHOs should consider requesting and 

reviewing the employer’s production records to aid in determining 

whether the employer’s monitoring was representative. 

b. CSHOs should interview employees to determine which shifts and 

tasks have the greatest exposures, and review the time periods for 

the samples collected to determine whether the sample times were 

representative of the work hours and also whether samples were 

collected in the employee’s breathing zone.

c. The 8-hour TWA exposure is generally best measured by

collecting at least one 8-hour air sample from the representative

employee, or by collecting two consecutive 4-hour samples. 

However, the employer (or CSHO) may encounter some situations

in which it might be more effective to collect a short-term sample 

during each task, such as where multiple and different silica 

exposure tasks are performed throughout the work shift, or the 

work shift is longer than 8 hours.

• Although it is preferable to sample between 7 and 8 hours of

exposure, if an employee’s silica exposure is known to be limited 

to a portion of the 8-hour work shift, exposure may be determined

by sampling only during the exposure period and documenting 

that there was no additional silica exposure during the remainder 
25

of the employee’s work shift. See OTM Section II: Chapter 1-

Personal Sampling for Air Contaminants guidance.

Note: If an employer appears to have switched sampling options from 

scheduled monitoring to performance, CSHOs should evaluate the 

employer’s equipment and work practices to ensure they reflect the 

operations upon which the assessment was based (see GI FAQ # 7).

3. Citation Guidelines. 

The following citation guidelines apply whenever employee exposure is 

reasonably expected to exceed the AL (Inspection Guidelines above has

more information on determining reasonably expected exposure levels).

a. For construction employers with employees engaged in a task 

identified on Table 1, a citation should not be issued for failure to 

assess when the employer has fully and properly implemented the 

specified engineering controls, work practices, and respiratory 

protection on Table 1 (see Section IX.E.1.a.).

• If a construction employer has not fully and properly implemented 

the specified engineering controls, work practices, and respiratory 

protection on Table 1 and has not conducted an exposure 

assessment, the employer should be cited for a grouped violation 

of 29 CFR § 1926.1153(c)(1) and paragraph (d)(2). Any other 

noted deficiencies should be separately cited (e.g., hazard 

communication). 

b. For general industry/maritime employers or for construction tasks 

not listed in Table 1:

• If the employer has not conducted an exposure assessment, the

employer should be cited for a violation of 29 CFR §

1910.1053(d)(1) or 29 CFR § 1926.1153(d)(2)(i), as appropriate.

• If the CSHO determines that the employer’s assessment of an 

employee’s full-shift exposure is inadequate because of 

insufficient sampling time and/or insufficient documentation, then 

cite 29 CFR § 1910.1053(d)(1) (grouped with 29 CFR §

1910.1053(d)(2) or paragraph (d)(3), as appropriate) in general 

industry or 29 CFR § 1926.1153(d)(2)(i) (grouped with 29 CFR §

1926.1153(d)(2)(ii) or paragraph (d)(2)(iii), as appropriate) in 

construction.

• If the employer is using the performance option and the CSHO

determines that significant differences exist between the air 
26

monitoring and/or objective data and current conditions which 

could cause the employee exposure to be underestimated or the 

employer’s assessment was inadequate because the employer 

failed to assess exposures on all shifts for each job in each work 

area (e.g., the data do not meet the criteria discussed above), then 

cite 29 CFR § 1910.1053(d)(2) or 29 CFR §1926.1153(d)(2)(ii), as 

well as any other applicable paragraphs.

• If the employer is using the scheduled monitoring option, but 

samples are inappropriately-applied area (environmental) samples 

or other non-personal results, or if the employer’s personal air 

samples are not representative of employees on each shift, each 

job, and in each work area, then cite 29 CFR §1910.1053(d)(3)(i) 

or 29 CFR § 1926.1153(d)(2)(iii)(A), as appropriate. In making 

this determination, evaluate whether:

o The samples are area (environmental) samples and do not

represent personal exposures; 

o The employer’s personal air samples do not cover the entire 

exposure period or all tasks; or

o The employer is using representative sampling, but the 

employer’s personal air samples are not representative, or the 

employer failed to sample the employee(s) who were expected 

to have the highest exposure to respirable crystalline silica.

• If the employer is using the scheduled monitoring option and the 

employer failed to repeat required monitoring within the specified 

timeframe, then cite 29 CFR § 1910.1053(d)(3)(iii)-(v) or 29 CFR 

§ 1926.1153(d)(2)(iii)(C)-(E) as applicable.

5. Reassessment of exposures. 29 CFR § 1910.1053(d)(4) and 29 CFR § 

1926.1153(d)(2)(iv) require employers to reassess exposures as follows:

When a change in production, process, control equipment, personnel or 

work practices may reasonably be expected to result in new or additional 

exposures at or above the AL.

• Whenever an employee performs a different operation and/or

moves to a different work location that may result in new or 

additional exposures at/or above the AL unless the original 

determination considered these operations; 

• Reassessment is not required when the same task is moved from an 

indoor to an outdoor location, or when a product is replaced with
27

another product that has lower crystalline silica content in the same 

process.

6. Inspection Guidelines.

a. When the employer’s exposure assessment does not reflect the 

exposures being observed, ask the employer and employees about 

any changes in the production, process, control equipment, 

personnel, or work practices that could affect respirable crystalline 

silica exposures. If operations changed, review documentation of 

the employer’s assessment of the new exposure scenario(s).

b. CSHOs should conduct sampling as necessary to determine 

whether employers have accurately characterized the exposure of 

each employee to respirable crystalline silica, and to document 

exposures the employer failed to assess. Refer to the previous 

guidance on air sampling under Section IX.C, Permissible 

Exposure Limit.

7. Citation Guidelines.

If the employer failed to reassess exposures when there was a change in 

the production, process, control equipment, personnel, or work practices 

that may reasonably be expected to result in new or additional exposures 

at or above the AL, or the employer had reason to believe new or 

additional exposures at or above the AL occurred, CSHOs should cite 

29 CFR § 1910.1053(d)(4) or 29 CFR §1926.1153(d)(2)(iv), as 

appropriate.

8. Methods of sample analysis. 29 CFR § 1910.1053(d)(5) and 29 CFR § 

1926.1153(d)(2)(v) require that all air monitoring samples taken to satisfy 

the monitoring requirements of paragraph (d) must be evaluated by a 

laboratory that analyzes air samples for respirable crystalline silica in 

accordance with the procedures in Appendix A of the silica standards.

a. The employer must ensure that the laboratory is accredited and 

follows the specifications outlined in Appendix A to the silica 

standards. The employer must include the identity of the 

laboratory on its air monitoring data.

Note: Refer to the silica standards’ Appendix A for more requirements. 

Also, the AIHA Laboratory Accreditation Programs maintains a website 

where the public can check on the accreditation status of labs at:

http://www.aihaaccreditedlabs.org/AccreditedLabs/Pages/default.aspx.
28

9. Inspection Guidelines.

Refer to the previous guidance on sampling under Section IX.C,

Permissible Exposure Limit and Appendix B of this Instruction for 

detailed instructions for collecting air samples. The silica standards allow 

employers to use any sampling device that conforms to the International 

Organization for Standardization (ISO) and the European Committee for 

Standardization (CEN) convention. OSHA uses the Dorr-Oliver cyclone 

with a flow rate of 1.7 L/min.

10. Citation Guidelines.

If the employer fails to follow the requirements for sample analysis in 

Appendix A of the silica standards, CSHOs should cite the employer 

under 29 CFR § 1910.1053(d)(5) or 29 CFR §1926.1153(d)(2)(v),

accordingly.

11. Employee notification. 29 CFR § 1910.1053(d)(6) and 29 CFR § 

1926.1153(d)(2)(vi) require employee notification of assessment results. 

If the employer assesses exposure in accordance with the performance 

option, the period for notification begins when the employer completes the

assessment. The exposure assessment under the performance option is 

considered completed when the employer has characterized an employee’s 

8-hour TWA exposure to respirable silica based on air monitoring data, 

objective data, or a combination of the two.

If the employer assesses exposure in accordance with the scheduled 

monitoring option, the period for notification begins when the employer 

receives the monitoring results. This is the case whether the employer 

conducts the exposure assessment internally or uses a third party to 

perform the exposure assessment. The standard does not provide extra 

time for notification in cases when it takes longer than the time permitted 

under the standard for the employer to analyze the sampling results or put 

them into a report.

General Industry and Maritime.

a. 29 CFR § 1910.1053(d)(6)(i) requires employers to notify each 

affected employee individually, in writing, of the results of the 

exposure assessment within 15 working days after completing an 

exposure assessment in accordance with paragraph (d) of the 

standard. The employer has the option to post the results in an 

appropriate location accessible to all affected employees (instead 

of notifying each affected employee individually) (see GI FAQ 

#23).
29

b. 29 CFR § 1910.1053(d)(6)(ii) requires that whenever an exposure 

assessment indicates that employee exposure is above the PEL, the 

employer must further describe in the written notification the 

corrective action being taken to reduce employee exposure to or 

below the PEL.

Construction.

c. 29 CFR § 1926.1153(d)(2)(vi)(A) requires construction employers 

to notify each affected employee in writing of the results of an 

assessment, or post the results in an appropriate location accessible 

to all affected employees within five working days after 

completing an exposure assessment. 

d. 29 CFR § 1926.1153(d)(2)(vi)(B) requires that when an exposure 

assessment indicates employee exposure above the PEL, the 

employer’s written notification must further describe the corrective 

action being taken to reduce employee exposure to or below the 

PEL.

Note: The term “affected” means all employees whose exposures were 

assessed, including employees whose exposures were determined by 

representative sampling and employees whose exposures were determined 

by objective data.

12. Inspection Guidelines.

The CSHO should ask employees whether and when they were given copies 

of the results of their exposure assessment, or when and where the results 

were posted.

13. Citation Guidelines.

If employees have not been notified of their exposure assessment results 

within timeframes specified above, CSHOs should cite 29 CFR § 

1910.1053(d)(6)(i) or 29 CFR § 1926.1153(d)(2)(vi)(A) for the relevant 

industry. If the employer’s written notification did not explain corrective 

action being taken for exposures exceeding the PEL, then cite 

29 CFR § 1910.1053(d)(6)(ii) or 29 CFR § 1926.1153(d)(2)(vi)(B) for the 

relevant industry.

14. Observation of monitoring. 29 CFR § 1910.1053(d)(7) and 29 CFR § 

1926.1153(d)(2)(vii) provide affected employees or their designated 

representatives with an opportunity to observe air monitoring conducted to 

assess silica exposures. 
30

a. Employers are required to provide the employee or the employee’s 

designee with protective clothing and equipment at no cost, when 

observation of monitoring requires entry into an area where the use 

of protective clothing or equipment is required for any workplace 

hazard. The employer must ensure that observers, including 

observers not employed by the employer, use such clothing and 

equipment.

15. Inspection Guidelines.

a. Ask affected employees or their designated representative if they 

were given the opportunity to observe any monitoring of employee 

exposure and whether they were provided with the appropriate 

protective clothing and equipment.

b. Ask affected employees or their representative if the protective 

clothing and equipment were worn.

16. Citation Guidelines:

a. If affected employees or their representatives were not provided 

the opportunity to observe monitoring, or were not provided with 

the appropriate protective clothing or equipment at no cost during 

observation, CSHOs should cite 29 CFR § 1910.1053(d)(7)(i) 

and/or paragraph (d)(7)(ii) or 29 CFR § 1926.1153(d)(2)(vii)(A) 

and/or paragraph (d)(2)(vii)(B), as appropriate.

b. If the employer did not ensure affected employees and/or their 

representative observing monitoring used the provided protective 

clothing and equipment, CSHOs should cite § 1910.1053(d)(7)(ii) 

or § 1926.1153(d)(2)(vii)(B).

E. Table 1- Specified exposure control methods (29 CFR § 1926.1153).

1. The construction standard requires employers to control their employees’ 

exposure to respirable crystalline silica. The standard provides employers 

with two options for achieving compliance. The first option is to use the 

Specified exposure control methods approach in 29 CFR § 1926.1153(c). 

For each employee engaged in a task identified on Table 1, paragraph 

(c)(1) requires employers to fully and properly implement the engineering 

controls, work practices, and respiratory protection set forth for the 

relevant task on Table 1. Table 1 includes some common construction 

tasks and equipment that are known to generate high exposures to 

respirable crystalline silica. 
31

The second option is to follow 29 CFR § 1926.1153(d), Alternative 

exposure control methods. For tasks not listed on Table 1, or where the 

employer does not fully and properly implement the engineering controls, 

work practices, and respiratory protection described on Table 1, the 

employer must comply with 29 CFR § 1926.1153(d).

a. Employees Engaged in a Table 1 Task. The phrase “employees 

engaged in Table 1 tasks” includes employees involved in the 

Table 1 task, even if they are not operating the equipment listed on 

Table 1 (e.g., laborers and other employees, including supervisors, 

who are assisting with the task or have some responsibility for the 

completion of the task). When respiratory protection is required 

for a task, all employees engaged in that task must be provided 

with the required protection. 

• For example, where an employee is assisting another employee 

operating a walk-behind saw indoors by guiding the saw, both the 

saw operator and the helper who is assisting the operator are 

considered engaged in the task and would need to wear a 

respirator.

• Similarly, employees assisting a worker jackhammering outdoors 

(e.g., a crew member using a water hose to spray and wet the 

concrete) would be considered to be engaged in the task and would 

also be required to wear a respirator for work lasting more than 

four hours.

• An employee directing traffic around another employee 

jackhammering would not be considered engaged in the task, and,

therefore, would not be covered by Table 1.

b. Fully and properly implementing the specified exposure control 

methods. The presence of the specified controls is not sufficient to 

constitute “fully and properly” implementing these controls. In 

order to be in compliance with paragraph (c)(1), employers must 

ensure that the controls are present, implemented and maintained,

and that employees understand the proper use of these controls and 

use them accordingly. 

2. Specified Engineering and Work Practice Controls. The controls on Table 

1 involve use of ventilation, wet methods, enclosed cabs, and, for some 

tasks, respiratory protection in addition to engineering and work practice 

controls. The following criteria apply to particular types of engineering 

controls and work practices or specific pieces of equipment listed on Table

1:
32

a. Dust Collection Systems. Some entries on Table 1 specify the use 

of a tool that is equipped with or uses a dust collection system. For 

example, one of the required engineering controls in paragraph

(c)(1)(xi) for employees using a handheld grinder for mortar 

removal (i.e., tuckpointing) is using a grinder equipped with a 

commercially available shroud and dust collection system.

A dust collection system typically consists of an industrial vacuum 

with an exhaust filter, a hose that connects the vacuum to the tool, 

and a shroud or cowling or, in the case of milling machines and 

vehicle-mounted drilling rigs, an enclosure that contains the source 

of the dust. Full and proper implementation of a dust collection 

system typically includes the following:

• The shroud or cowling must be properly sized, intact, and installed 

in accordance with the manufacturer’s instructions;

• The hose connecting the tool to the vacuum must be intact and 

without kinks or tight bends that reduce the suction. Employers 

must use the hose lengths specified by the manufacturer (extension

hoses or the addition of multiple inlets will reduce the air flow);

• The filter(s) on the vacuum must be cleaned or changed in 

accordance with the manufacturer’s instructions to prevent 

overflowing or clogging, which reduces suction and would prevent 

the vacuum system from operating effectively;

• The filters and dust should be handled so as to minimize worker 

exposures to silica dust. This could involve disposing of filters and 

dust in sealed containers, such as heavy-duty plastic bags, to 

prevent the release of dust into the air;

• The vacuum system must provide the air flow specified on Table 1,

or where no air flow is specified, the air flow recommended by the 

equipment manufacturer;

• The vacuum system must have a filter with a 99 percent or greater 

efficiency;

• For most entries, Table 1 requires the vacuum system to have a 

filter-cleaning mechanism; in some cases (e.g., paragraph (c)(1)(xi) 

handheld grinders for mortar removal and paragraph (c)(1)(xii) 

handheld grinders for uses other than mortar removal), a cyclonic 

pre-separator can be used as an alternative to a filter-cleaning 

mechanism. If so equipped, it may be necessary to activate a backpulse filter cleaning mechanism several times during the course of 
33

a shift; and,

• The dust collection bags/container must be emptied regularly to 

avoid overfilling, which would prevent the vacuum system from 

operating effectively.

Note: Several of the entries on Table 1 specify that the dust collection 

system must be commercially available. This ensures that employers use 

equipment that is appropriately designed for the tool being used and that 

will be effective in capturing dust generated from using the tool. Products 

that are custom-made by aftermarket manufacturers and that are intended 

to fit the make and model of the tool are considered commercially 

available. This requirement is intended to exclude do-it-yourself on-site 

attempts at dust control using substandard or otherwise inappropriate 

control equipment. Employers who use controls other than those specified 

on Table 1 must comply with 29 CFR § 1926.1153(d).

b. Wet methods: Most of the eighteen entries on Table 1 specify the 

use of wet methods to control exposures: 

• For example, paragraph (c)(1)(xiv), small drivable milling 

machines (less than half-lane), specifies the use of a machine 

equipped with supplemental water sprays designed to suppress 

dust;

• Some of the entries on Table 1 that specify the use of wet methods 

require that the delivery system must be "integrated" into the tool. 

For example, paragraph (c)(1)(i), stationary masonry saws,

requires the use of a saw equipped with an integrated water 

delivery system that continuously feeds water to the blade. An 

integrated water delivery system is one developed by the 

manufacturer in conjunction with the tool. Integrated systems are 

able to control dust emissions more effectively by applying water 

at the appropriate dust emission points (e.g., where the blade meets 

the work piece) based on tool configuration;

• Where Table 1 requires an integrated control system, employers 

that use a non-integrated system (e.g., a worker spraying water 

from a hose on material that another worker is cutting with a 

stationary masonry saw) have not fully and properly implemented 

the controls specified on Table 1 and must comply with all the 

requirements of 29 CFR § 1926.1153(d);

• Where wet methods are implemented for dust control, full and 

proper implementation of controls under Table 1 involves ensuring 

the following:
34

o The availability of a sufficient supply of water on-site to 

suppress the dust. Where connection to a water main or outlet

is not available, water must be provided using portable tanks or 

water trucks;

o A steady spray of water is directed at the point of dust 

generation at the flow rate sufficient to minimize release of 

visible dust; and

o A reliable water delivery system, which would include

frequent checking for clogging of the spray nozzles.

Note: The possibility for freezing may occur during water application in 

some regions. Employers should consider using heated water or shelters,

or adding environmentally-friendly anti-freeze to the water where work is

performed in sub-freezing temperatures. Precautions must be taken to 

ensure that use of water in freezing temperatures does not create a slip 

hazard.

c. Enclosed cabs: Four of the entries on Table 1 specify the use of an 

enclosed cab or booth. For example, 29 CFR §

1926.1153(c)(1)(xvii), heavy equipment and utility vehicles used 

to abrade or fracture silica-containing materials (e.g., hoe-ramming

or rock ripping) or used during demolition activities involving 

silica-containing materials, specifies that the equipment must be 

operated from within an enclosed cab. As described below, 29 

CFR § 1926.1153(c)(2)(iii) contains further requirements for an 

enclosed cab or booth.

Note: In this context, abrade means scraping or wearing away silicacontaining materials through friction.

3. Manufacturer’s instructions. Most of the entries on Table 1 require that 

the equipment must be operated and maintained in accordance with 

manufacturer’s instructions to minimize dust emissions. This means that 

employers must follow manufacturer instructions that are related to dust 

control. In determining which instructions might relate to dust control, 

employers should consider whether the failure to follow the particular 

instruction would increase employee exposure to silica. Examples of 

manufacturer instructions for minimizing dust emissions, as listed in CON

FAQ #9, could include: 

a. Instructions on the use of water, water supply, and flow rates, 

including installation and maintenance of integrated water delivery 

systems.
35

b. Instructions on when to change water, where water supply is 

reused.

c. Instructions on the use, installation, and maintenance of dust 

collectors or vacuums, including recommended flow rate (cubic 

feet per minute (CFM)), HEPA filters, and capacity.

d. Instructions on the maintenance and replacement of blades.

e. Instructions on the rotation (e.g., speed, direction) of blades.

Examples of manufacturer instructions that are not generally related to 

minimizing dust emissions include:

a. Warnings related to electrical, guarding, and noise hazards.

b. Instructions regarding the use of personal protective equipment 

(including respiratory protection).

c. Instructions on fueling and refueling.

d. Instructions on transporting the tool from worksite to worksite.

Where a given instruction is reasonably related to the level of dust 

generated, the standard requires employers to follow that 

instruction, regardless of whether that instruction serves more than 

one purpose. OSHA recognizes that sometimes manufacturers 

adopt particular instructions to serve multiple purposes, and the 

manufacturers’ instructions that do not relate to minimizing dust 

emissions may still be relevant to compliance with other OSHA 

standards and the OSH Act (see CON FAQ #9).

4. Heavy equipment and utility vehicles. Under 29 CFR §

1926.1153(c)(1)(xvii), engineering controls and work practices must be 

used when heavy equipment or utility vehicles are used to abrade or 

fracture silica-containing materials (e.g., hoe-ramming, rock-ripping) or 

used during demolition activities involving silica-containing materials. 

Employees engaged in this task operate a variety of wheeled or tracked 

vehicles ranging in size from large heavy construction equipment, such as 

bulldozers, scrapers, loaders, cranes and road graders, to smaller and 

medium sized utility vehicles, such as tractors, bobcats and backhoes, with 

attached tools that are used to move, fracture, or abrade rock and 

demolition debris. 
36

Equipment operators typically perform activities such as the demolition of 

concrete or masonry structures. Some activities vary in amounts of dust 

generated and thus the level of silica exposure for employees engaged in 

particular operations could also vary. 

a. When operating heavy equipment and utility vehicles used to 

abrade or fracture silica-containing materials or used for 

demolition activities involving silica-containing materials, Table 1 

requires the equipment operator to be in an enclosed cab. Some 

types of heavy equipment already come equipped with enclosed, 

filtered cabs that meet the requirements of Table 1. The use of an 

enclosed cab as the only control is an option if the operator is the 

only employee engaged in the task. However, if other employees 

outside the cab are engaged in the task, water and/or dust 

suppressants must be applied as necessary to minimize dust 

emissions.

b. No respiratory protection is required for employees engaged in this 

task when the requirements of paragraphs (c)(1)(xvii) and 

(c)(2)(iii) are met:

For example, heavy equipment and utility vehicles used for tasks

such as grading and excavating do not typically generate high 

levels of dust. Table 1 requires that water and/or dust suppressants 

must be applied as necessary to minimize dust emissions. 

(29 CFR § 1926.1153(c)(1)(xviii)). Alternatively, if the equipment 

operator is the only employee engaged in the task, the operator can 

operate the equipment from within an enclosed cab (instead of 

using wet methods and/or dust suppressants). In either case, no 

respiratory protection is required.

Note: The railroad industry also uses heavy equipment to dump and grade 

silica-containing ballast in track work to support the ties and rails. Such 

track work is generally subject to OSHA’s construction standards 

including the silica standards for those employees working outside the 

cab, while the employee inside the cab is covered by Federal Railroad 

Administration standards.

5. Respiratory protection. Six of the entries on Table 1 specify the use of 

respiratory protection in certain specified circumstances and indicate the 

minimum APF. For a number of these entries, whether respiratory 

protection is required by Table 1 depends on the task location and the task 

duration. 

a. Task Location. Some entries (e.g., 29 CFR § 1926.1153(c)(1)(iv), 

walk-behind saws) require respirators when the task is performed 

indoors or in an enclosed area. This includes any area where, 
37

without the assistance of forced ventilation, the dispersal of 

airborne dust can be impeded and concentrations can accumulate

(see CON FAQ #13).

• For example, a work area with only a roof that does not affect the 

dispersal of dust would not be considered enclosed; however, an 

open-top structure with three walls and limited air movement could 

be considered enclosed. Parking garages, pits, trenches, and 

swimming pools may qualify as an enclosed area.

b. Task Duration. For some entries on Table 1 (e.g., 

29 CFR § 1926.1153(c)(1)(x), jackhammers and handheld 

powered chipping tools) respirator requirements are based on the 

duration the task is performed, i.e., “less than or equal to four 

hours/shift” or “greater than four hours/shift.” If respiratory 

protection is required for either or both of these time periods, the 

applicable column in the respiratory protection column on Table 1 

specifies the minimum APF required.

Before the task is performed, the employer must make a good-faith 

judgment of the task’s anticipated duration over the work shift, and 

whether the task is performed continuously or intermittently. The 

estimate should be based on previous experience and other 

available information. If the employer anticipates that an 

employee will be engaged in a task for more than four hours, 

measured from the beginning of the task, the employer must 

provide the employee with the required respiratory protection at 

the beginning of the shift (see CON FAQ #14). 

Where tasks are anticipated to last four hours or less, but

employees encounter an unforeseen delay that could extend the 

task duration beyond four hours, the employer must provide the 

respiratory protection required in the “greater than four 

hours/shift” column as soon as it becomes evident that the total 

task duration may exceed four hours. 

• If Table 1 indicates that respiratory protection is required 

whenever the anticipated task duration exceeds four hours,

employees engaged in the task must wear the specified respirator 

during the entire time that the task is conducted (i.e., at the start of 

the task), not just the period of time that exceeds four hours;

• When determining the silica-related task duration, the duration 

begins when the tool or equipment is first put into operation and 

continues until the employee completes the task. This time 
38

includes intermittent breaks in tool usage and clean-up. If, 

however, there are extended intervals with no silica exposures, the 

time intervals during which the employee performs tasks not listed 

on Table 1 need not be included in calculation of the silica-related 

task duration.

c. Calculating Task Duration. 29 CFR § 1926.1153(c)(3) explains 

how the task duration factor should be calculated where an 

employee performs more than one task on Table 1 during the 

course of a shift. If an employee performed more than one Table 1 

task in a shift, the duration of the task (and thus the required 

respiratory protection) is determined by the combined total 

duration of all the Table 1 tasks. 

• Where an employee performs more than one task on Table 1 

during the course of a shift, and the total duration of all tasks 

combined is less than 4 hours, the required respiratory protection 

(if any) for each task is the protection specified in the 4 hours or 

less column. 

• If the total duration of all Table 1 tasks combined is more than 4 

hours per shift, the required respiratory protection for each task is 

the protection specified in the more than 4 hours per shift column. 

The following examples illustrate this concept:

o Example 1: An employee plans to use a handheld grinder 

(Table 1, (xii)) for 3 hours outdoors to grind/smooth concrete 

surfaces, and then run a chipping hammer (Table 1, (x)) for 2 

hours outdoors, for a total duration of five hours. No respirator 

is required when grinding outdoors using a grinder equipped 

with either a water delivery system or a vacuum dust collection 

system. Table 1 requires the use of a respirator with an APF of 

10 when using the chipping hammer for more than 4 hours. 

Because the combined duration of both tasks is more than 4 

hours, a respirator is required the entire time the employee uses 

the chipping hammer.

o Example 2: An employee plans to use a handheld grinder 

(Table 1, (xii)) indoors for 3 hours with a dust collector to 

grind/smooth concrete walls, and then uses a chipping hammer 

(Table 1, (x)) outdoors for 2 hours during the same shift. The 

combined duration is 5 hours. The employee must use 

respiratory protection during the entire 5 hours while

performing both tasks, not just the period of time that exceeds 
39

4 hours, because both tasks require a respirator for more than 4 

hours/shift. 

o Example 3: An employee plans to use a handheld grinder 

(Table 1, (xii)) with a dust collector to grind/smooth concrete 

for 3 hours indoors in the morning, and then for 2 hours for 

mortar removal (i.e., tuckpointing), (Table 1, (xi)), outdoors in 

the afternoon. The combined duration is 5 hours. The use of a 

respirator is required for both tasks because the first task 

requires a respirator with an APF of 10 for more than 4 hours 

and the second task requires a respirator with an APF of 25 for 

task durations greater than 4 hours. In this scenario, the 

employee must either wear the respirator with an APF of 10 

while using the grinder to grind/smooth concrete, and then a 

respirator with an APF of 25 while using the grinder for mortar 

removal or tuckpointing, or use a respirator with an APF of 25 

for the entire 5 hours.

Note: If multiple tasks are estimated to last 4 hours or less, but the tasks 

will take more than 4 hours total, the employer must immediately reexamine the respiratory protection requirements to determine whether a 

respirator, or a respirator with a higher assigned protection factor, is 

needed.

6. Additional Specifications. 29 CFR § 1926.1153(c)(2) contains additional 

specifications that apply when implementing the control measures 

specified in Table 1. To fully and properly implement Table 1, employers 

must follow these specifications, when applicable:

a. For tasks performed indoors or in an enclosed area, paragraph

(c)(2)(i) requires employers to provide a means of exhaust as 

needed to minimize the accumulation of visible airborne dust;

• The means of exhaust could include dilution ventilation through 

the use of portable fans (e.g., box fans, floor fans, axial fans) to 

introduce air into the space, portable ventilation systems, or other 

systems that increase air movement and assist in the removal and 

dispersion of airborne dust. To be effective, the ventilation must 

be set up so that movements of employees during work, or the 

opening of doors and windows, will not negatively affect the 

airflow (i.e., so that it does not contribute to an employee’s 

exposure). 
40

b. For tasks performed using wet methods, paragraph (c)(2)(ii) 

requires employers to apply water at flow rates sufficient to 

minimize release of visible dust; and

• Adequate dust capture is dependent on a variety of factors such as 

dust particle size, blade velocity, spray nozzle size and location, 

use of surfactants or other binders, and environmental factors 

(water hardness, humidity, and weather) that must be considered 

when implementing wet methods.

c. For measures implemented that include an enclosed cab or booth, 

paragraph (c)(2)(iii) requires employers to ensure that the cab or 

booth:

• Is maintained as free as practicable from settled dust;

• Has door seals and closing mechanisms that work properly;

• Has gaskets and seals that are in good condition and work 

properly;

• Is under positive pressure maintained through continuous delivery 

of fresh air;

• Has intake air through a filter that is 95 percent efficient in the 0.3-

10.0 μm range (e.g., Minimum Efficiency Reporting Value or 

MERV-16 or better); and

• Has heating and cooling capabilities.

7. Inspection Guidelines for Table 1- Specified Exposure Control Methods.

a. 29 CFR § 1926.1153(c)(1)-Table 1: The CSHO should determine 

whether any employees are engaged in a task listed on Table 1 or 

using the tools or equipment listed on Table 1 on materials 

containing crystalline silica. If so, the CSHO should consult Table 

1 to determine whether the employees are using the engineering 

controls, work practices, and respiratory protection specified on 

Table 1 for that particular task or equipment, including following 

the additional specifications contained in paragraphs (c)(2) and 

(c)(3).

b. If the CSHO determines that the employees are not using any of 

the engineering controls, work practices, and/or respiratory 

protection specified on Table 1 for a particular Table 1 task or 

equipment, the CSHO should conduct air sampling, as necessary.
41

Note: Table 1 operations requiring respirator use will likely exceed the 

PEL.

c. If the CSHO determines that the employees are using all of the

engineering controls, work practices, and/or respiratory protection 

specified on Table 1 for that particular task or equipment, then the 

CSHO should evaluate whether the employer has “fully and

properly implemented” the specified control methods. For further 

guidance, see this Instruction’s Appendix A.

d. To determine if the employer is fully and properly implementing 

the specified control methods described on Table 1, the CSHO 

should:

• Request and review the employer’s written ECP and other relevant 

programs (e.g., respiratory protection, hazard communication, etc.)

and observe the work operation(s);

Note: As described in more detail in Section IX.G.4 of this Instruction, an 

employer’s written ECP must list the specific tasks that involve exposure 

to respirable crystalline silica, and for each task, a description of 

engineering controls, work practice controls, and the respiratory protection 

that will be implemented (see GI FAQs #32 - #34, CON FAQs #30 - #38).

• Interview employees to gather all pertinent information regarding 

the task, including the materials used and the length of time spent 

on each task;

• Take photos/videos of tools/equipment and controls and note the 

make/model of tools or equipment used;

• Where the applicable entry on Table 1 references the 

manufacturer’s instructions, request and view those instructions;

• Visually observe the level of dust generated during the 

performance of a Table 1 task. The presence of large amounts of 

visible dust generally indicates that controls have not been fully 

and properly implemented. A small amount of dust can be 

expected even with equipment operating as intended by the 

manufacturer; however, a noticeable increase in dust generation 

during the operation of the equipment can be an indication that the 

dust controls are not operating correctly; and

• Evaluate the employer’s equipment maintenance program and its 

respiratory protection program.
42

e. Construction tasks/operations that are not included on Table 1 and 

Table 1 tasks where the employers have implemented controls 

other than those specified on Table 1 are covered under

§ 1926.1153(d) - Alternative exposure control methods. This 

includes the requirement to conduct an employee exposure 

assessment.

f. If the CSHO has questions about whether an employer has fully 

and properly implemented the controls specified on Table 1 and 

observes a hazardous condition (e.g., excessive silica dust), air 

monitoring should be conducted as necessary to determine the 

level of exposure. 

g. The CSHO should determine the task location through employee 

interviews and observation (i.e., whether an area is outdoors, 

indoors, or enclosed). 

• If a task is performed indoors or in an enclosed area the CSHO 

should:

o Document the task location by taking pictures of the structure 

and any presence/accumulation of airborne dust. 

o Ask the employees whether airborne dust builds up while they 

are performing their tasks. 

o Determine whether employers are providing a means of

exhaust (e.g., portable fans or other systems that increase air 

movement and assist in the removal and dispersion of airborne 

dust) to minimize accumulation of visible airborne dust, as 

required by paragraph (c)(2)(i). 

h. If employees are engaged in tasks on Table 1 that require the use 

of wet methods, the CSHO should request and review the 

equipment’s instructions, observe the equipment in use, and 

interview employees to determine whether the water is being 

applied at flow rates (e.g., those recommended by the tool 

manufacturer) sufficient to minimize release of visible dust, as 

required by paragraph (c)(2)(ii). 

i. If employees are engaged in a task on Table 1 that requires the use 

of control measures that include an enclosed cab or booth, the 

CSHO should request and review the equipment manufacturer’s 

instructions, inspect the equipment, and interview employees to 

determine whether the equipment complies with paragraphs

(c)(2)(iii)(A)-(F).
43

j. The CSHO should interview employees, the competent person, and 

the employer representative(s) to determine: in what task(s) 

employees are engaged; how long each task is estimated to take; 

how long the task(s) actually took; whether the employer provided 

respirators in accordance with Table 1; whether the employees 

wore respirators while engaged in the task(s) requiring its use; and, 

if so, what the APF was for the respirators worn.

8. Citation Guidelines for tasks listed on Table 1:

a. Where a construction employer is performing a task listed on Table 

1 and is not following the specified controls, the employer is 

required to assess and limit exposure in accordance with

29 CFR § 1926.1153(d). If employee sampling shows exposure 

over the PEL and the employer fails to implement feasible 

engineering and work practice controls to reduce employee 

exposure to or below the PEL, the CSHO should cite applicable 

sections of both 29 CFR § 1926.1153(c) and paragraph (d) and 

group them.

• Example: If an employee is dry cutting with a stationary masonry 

saw (i.e., no water is used), no employer exposure assessment was 

conducted, and sampling shows exposure over the PEL, the CSHO 

should cite paragraphs (c)(1)(i) and (d)(1), (d)(2)(i), and (d)(3)(i)

as a grouped violation.

b. Where the employer is using but not fully and properly 

implementing the Table 1 controls and sampling shows

overexposure, then cite the appropriate section of 29 CFR § 

1926.1153(c) and paragraph (d)(1) as a grouped violation, and any 

other noted deficiencies (e.g. hazard communication) as separate 

violations. 

• Example: If an employee is using a handheld power saw indoors 

but not fully and properly implementing the Table 1 controls (e.g., 

not using the manufacturer’s recommended airflow or greater),

then cite 29 CFR § 1926.1153(c)(1)(ii) and paragraph (d) as 

grouped violations.

Note: If a construction employer has not fully and properly implemented 

the specified controls for a Table 1 operation or task, the CSHO should

first assess whether the employer is in compliance with 29 CFR §

1926.1153(d), Alternative exposure control methods. Conduct sampling 

as necessary to determine employee exposure, i.e., whether exposures are 

at or above the AL or have exceeded the PEL.
44

c. CSHOs may encounter multiple silica-generating tasks being 

performed close to each other. Where it appears that one or more 

tasks are not fully and properly controlled by following Table 1,

CSHOs should sample the uncontrolled task(s). Where results 

show an overexposure, then cite the employer for the overexposure 

along with failure to restrict access to work areas 

(29 CFR § 1926.1153(g)(1)(iv)) and any observed deficiencies 

related to competent person oversight (29 CFR § 1926.1153(g)(4))

as separate violations. 

Note: Where the construction employer has not fully or properly 

implemented the controls on Table 1 or conducted an exposure 

assessment, but the CSHO has not been able to collect an air sample, 

consult with the AD before considering citations under 29 CFR §

1926.1153(c) and paragraph (d).

d. If the CSHO determines that respirator requirements on Table 1 

were not fully and properly implemented, the employer falls under 

paragraph (d), and the CSHO should conduct air sampling, as 

necessary to determine whether there is an overexposure. Any 

violation(s) under paragraph (d) shall be grouped with any 

violations of paragraph (c)(1) and (c)(3), as applicable.

F. Regulated Areas (General Industry/Maritime only).

The term “regulated area” is defined as an area where an employee’s silica 

exposure exceeds, or can reasonably be expected to exceed, the PEL 

(see 29 CFR § 1910.1053(b) and GI FAQs #25).

1. Establishing Regulated Areas. 29 CFR § 1910.1053(e)(1) requires the 

employer to establish a regulated area wherever an employee’s exposure 

to respirable crystalline silica is, or can reasonably be expected to be, in 

excess of the PEL.

Note: Regulated areas are not included in the construction standard. 

However, construction employers must comply with 29 CFR §

1926.1153(g)(1)(iv) and ensure that their written ECPs describe 

procedures for restricting access to silica work areas, when necessary, to 

minimize the number of employees exposed to respirable crystalline silica 

and their level of exposure. 

a. Regulated areas limit exposure to as few employees as possible. If

an employer has, and adequately enforces, work rules precluding 

employees from entering a particular area where exposures are 
45

reasonably expected to exceed the PEL, then the employer does 

not need to treat that location as a regulated area. OSHA notes that 

if one or more employees will enter the area long enough that it is

reasonable to expect their 8-hour TWA exposures to exceed the 

PEL, the employer must establish a regulated area and all 

employees entering that area must wear respirators (even those not 

in the area long enough for their exposures to exceed the PEL) (see

GI FAQ #25).

Note: Respirable crystalline silica levels in some areas, such as sand 

towers or traps under the shakeout operations in foundries or areas where 

employees are performing abrasive blasting, may be so high that any 

exposure could reasonably be expected to be in excess of the PEL. In 

such cases, the regulated area requirements in 29 CFR § 1910.1053(e) 

would apply, regardless of any employer work rules limiting (but not 

precluding) employee entry.

b. Paragraph (e)(2) requires employers to demarcate regulated areas 

from the rest of the workplace in a manner that minimizes the 

number of employees exposed to respirable crystalline silica within 

those areas and post signs at all entrances to regulated areas that 

bear the legend specified in 29 CFR § 1910.1053(j)(2). 

c. Traffic cones, stanchions, tape, barricades, lines, or textured 

flooring may all be effective means of demarcating the boundaries 

of regulated areas. In determining how to demarcate regulated 

areas, employers may consider factors such as the configuration of 

the area, whether the regulated area is permanent, the airborne 

respirable crystalline silica concentration, the number of 

employees in adjacent areas, and the period of time the area is 

expected to have exposure levels above the PEL (see GI FAQ 

#27).

d. Employers must post signs at all entrances to regulated areas with 

the prescribed hazard language in 29 CFR § 1910.1053(e)(2)(ii), 

(j)(2) (see GI FAQ #27). These signs must include the following

language:

DANGER

RESPIRABLE CRYSTALLINE SILICA

MAY CAUSE CANCER

CAUSES DAMAGE TO LUNGS

WEAR RESPIRATORY PROTECTION IN THIS AREA

AUTHORIZED PERSONNEL ONLY

Note: Employers may choose to include additional information on the 

signs required under the general industry/maritime standard, provided that 
46

the additional information included is not confusing or misleading and 

does not detract from warnings required by the standard.

e. Employers must limit regulated area access to employees 

authorized by the employer and required by work duties to be 

present in the regulated area, persons observing exposure 

monitoring, or any person authorized by the Occupational Safety 

and Health (OSH) Act or regulations issued under it to be in a 

regulated area, 29 CFR § 1910.1053(e)(3) (see GI FAQ #29).

f. Employers must provide each employee and the employee’s 

designated representative entering a regulated area with an 

appropriate respirator, in accordance with 1910.1053(g). 

Employers must require each employee or designated 

representative to use the respirator while in the regulated area, 

regardless of the length of time spent (see 29 CFR § 

1910.1053(e)(4)).

Note: Where the standard requires the use of respiratory protection, 

employers must institute a respiratory protection program in accordance 

with 29 CFR § 1910.134 (see 29 CFR § 1910.1053(g)(1)).

2. Inspection Guidelines.

a. If the employer has established a regulated area, observe the 

demarcation area and persons entering and exiting. Determine 

whether the employer has adequately demarcated a regulated area 

and whether the demarcation effectively warns employees not to 

enter unless they are authorized. CSHOs should:

• Ask employees whether they enter regulated areas and, if so, why;

and,

• Take photographs to document instances where regulated areas are 

not demarcated and where signs are not posted at entrances.

3. Citation Guidelines.

a. If CSHO air monitoring results indicate that exposures are above 

the PEL and the employer has not established a regulated area, cite 

29 CFR § 1910.1053(e)(1).

b. If the employer failed to demarcate the regulated area or post the 

required signage, cite 29 CFR § 1910.1053(e)(2)(i) and/or 

29 CFR § 1910.1053(e)(2)(ii), as appropriate. 
47

c. If non-compliance is related to signage, group the violation with 

29 CFR § 1910.1053(j)(2), as appropriate.

d. If the employer failed to limit access to the regulated area to those 

authorized by the standard, cite 29 CFR § 1910.1053(e)(3).

4. Respiratory Protection within a regulated area. 29 CFR § 1910.1053(e)(4) 

requires that employers must provide each employee and the employee’s 

designated representative entering a regulated area with an appropriate 

respirator in accordance with 29 CFR § 1910.1053(g) and shall require 

each employee and the designated representative to use the respirator 

while in the regulated area, regardless of the length of time spent in the 

regulated area.

5. Inspection Guidelines.

a. CSHOs should observe employees when they are entering and 

working inside the regulated areas.

b. CSHOs should interview employees, as well as their designated 

representatives, and document any observed deficiencies.

6. Citation Guidelines.

If the employer failed to provide each employee (or the employee’s

designated representative) entering a regulated area with an appropriate 

respirator, or failed to require the use of necessary respiratory protection, 

cite 29 CFR § 1910.1053(e)(4) and group with 29 CFR § 

1910.1053(g)(1)(iv).

G. Methods of Compliance.

1. Engineering and Work Practice Controls. 29 CFR § 1910.1053(f)(1) and

29 CFR § 1926.1153(d)(3)(i) establish that feasible engineering and work 

practice control methods shall be used by employers to reduce exposures 

to and maintain exposures at or below the PEL. In the case of the

construction PEL and exposure assessment requirements (see Sections 

IX.C and IX.D in this Instruction), these requirements apply for tasks not 

listed on Table 1, or where the employer does not fully and properly 

implement the specified control methods in 29 CFR § 1926.1153(c), Table 

1. For more information on Table 1, see Section IX.E of this Instruction. 

a. The silica standards require that employers institute feasible 

engineering and work practice controls (e.g., administrative 

controls) as the primary means to reduce and maintain employee 
48

exposures to respirable crystalline silica to levels at or below the 

PEL. 

However, if exposures remain above the PEL but the employer can 

demonstrate it has implemented all feasible engineering and work 

practice controls, then the employer is in compliance with 29 CFR 

§ 1910.1053(f)(1) and 29 CFR § 1926.1153(d)(3)(assuming the 

provision and use of required respiratory protection is in 

accordance with the standard).

b. Engineering controls prevent the release of silica-containing dust 

particles at the source of exposure and include process 

modification, enclosure or containment, substitution of less toxic 

materials, worker isolation, general and local ventilation with dust 

collection systems, and dust suppressants like water.

c. Work practice controls systematically modify how employees 

perform an operation, and often relate to the way employees use 

engineering controls, such as periodic inspection and maintenance 

of process and control equipment or housekeeping. 

d. If a particular engineering or work practice control not already 

implemented is feasible, the control shall be considered as an 

appropriate abatement method if other controls are not successful 

at reducing exposures to or below the PEL.

e. The silica standards do not prohibit the rotation of employees (a 

type of administrative control) to limit employee exposures. 

However, this practice is discouraged as a means of avoiding 

implementation of engineering and other work practice controls, 

due to potential difficulty maintaining employees’ exposures at/or 

below the PEL solely using rotation. Moreover, the use of rotation 

may require the employer to provide medical surveillance to 

additional workers and to train many workers on multiple jobs (see

GI FAQ # 30).

Note: Hydraulic fracturing operations in the oil and gas industry have 

until June 23, 2021, to implement feasible engineering controls to achieve 

the new PEL, 29 CFR § 1910.1053(l)(3)(ii). Until that time, when 

employee exposures exceed the PEL, employers must provide their 

employees with appropriate respiratory protection and ensure its use.

2. Inspection Guidelines. The CSHO should verify compliance with the 

engineering control and work practice requirements:

a. Observe employees using (or ask the employer to describe and/or 
49

demonstrate) the engineering and work practice controls to ensure 

that controls are present and appropriate.

b. If controls are implemented and exposures are still over the PEL 

and the employer claims that additional engineering or work 

practice controls are infeasible, it is the employer’s burden to 

prove infeasibility. The CSHO should ask the employer to provide 

information specific to the particular operation supporting its claim 

of infeasibility.

c. To assess whether an employer has reduced exposures to the 

lowest feasible level, evaluate its efforts to control exposures. 

Examples of evidence employers might offer to show that they 

have implemented all feasible engineering and work practice 

controls and reached the lowest feasible level of exposure include:

• Results of past control efforts;

• Evidence of previous/current efforts to control dust sources using 

widely recognized control measures; or

• Air monitoring results from before and after controls were 

implemented.

d. Evaluate employer efforts to prevent or fix malfunctions that 

would result in increased exposures (e.g., review whether the 

employer inspects and maintains controls, request preventive 

maintenance schedules and service records).

e. Evaluate the implementation of work practice controls, for 

example:

• Observe whether tools that use water to control dust spray water at 

the point of dust generation;

• Observe positioning of local exhaust hoods. 

f. In construction, for tasks not listed on Table 1 or where the 

employer has not fully and properly implemented the controls and 

respiratory protection on Table 1, the employer must comply with 

the requirements of 29 CFR § 1926.1153(d). The CSHO should

conduct personal sampling, when possible, and measure an 8-hour 

TWA to determine if exposures exceed the PEL and whether the 

employer has complied with the methods of compliance under 

29 CFR § 1926.1153(d)(3). 
50

g. Where the employees are only performing tasks outlined on Table1 and the employer is fully and properly implementing the 

protections described in 29 CFR § 1926.1153(c), 29 CFR §

1926.1153(d) is not applicable. See Table 1 flow chart in 

Appendix A of this Instruction to determine compliance with §

1926.1153(c) for those following Table 1. 

3. Citation Guidelines.

a. General Industry/Maritime.

• If exposures are above the PEL and a general industry/maritime 

employer has not instituted feasible engineering and work practice 

controls, or has not maintained the controls that are implemented, 

cite 29 CFR § 1910.1053(f)(1), grouped with 29 CFR § 

1910.1053(c).

• If CSHO air sampling results show that employees are exposed to

respirable crystalline silica above the PEL, and the employer has 

demonstrated that it has implemented all feasible engineering and 

work practice controls, and employees are adequately protected 

by an effective respiratory protection program, then no violation 

of 29 CFR § 1910.1053(f)(1) or paragraph (c) should be cited.

b. Construction.

• Where 29 CFR § 1926.1153(d) applies but the construction 

employer’s engineering and work practice controls are not 

reducing employee exposures to levels at or below the PEL and the 

employer cannot demonstrate infeasibility, then cite § 

1926.1153(d)(3)(i) and group with § 1926.1153(d)(1).

4. Written Exposure Control Plan. 29 CFR § 1910.1053(f)(2) and 29 CFR § 

1926.1153(g) establish requirements for the written ECP. These 

requirements are applicable to all covered entities (see GI FAQs #32 - #34

and CON FAQs #30 - #38).

a. All employers covered by the silica standards must establish and 

implement a written ECP.

b. Employers may develop a single comprehensive plan for each 

worksite that includes all of the silica-generating tasks that 

employees will perform at the worksite (i.e., employers do not 

need separate exposure control plans for different operations, 

processes, or shifts conducted at the same worksite). 
51

c. For construction, employers can develop a single comprehensive 

plan where employees are performing the same tasks at multiple 

worksites.

d. Employers must review and evaluate the effectiveness of the ECP 

at least annually and update as necessary

(29 CFR § 1910.1053(f)(2)(ii) and 29 CFR § 1926.1153(g)(2)) (see

GI FAQ #34).

e. Employers must make the ECP readily available for examination 

and copying, upon request, to each covered employee, their 

designated representative, OSHA and the National Institute for 

Occupational Safety and Health (NIOSH) (29 CFR §

1910.1053(f)(2)(iii) and 29 CFR § 1926.1153(g)(3)).

f. Written ECPs in both general industry/maritime and construction 

shall contain at least the following:

• Descriptions of tasks in the workplace that involve silica exposure 

as provided by 29 CFR § 1910.1053(f)(2)(i)(A) and 29 CFR § 

1926.1153(g)(1)(i);

• Description of engineering controls, work practices, and 

respiratory protection used to limit employee exposures for each 

task, as provided by 29 CFR § 1910.1053(f)(2)(i)(B) and 29 CFR § 

1926.1153(g)(1)(ii).

o These descriptions should include information such as types of 

controls used (e.g., dust collector with manufacturer’s 

recommended air flow and a filter with 99 percent efficiency), 

effective work practices (e.g., positioning local exhaust over 

the exposure source), how items such as filled vacuum bags 

will be handled, how slurry created when using water to 

control silica-containing dust will be managed to minimize 

employee exposure, and, if required, appropriate respiratory 

protection (e.g., a respirator with an APF of 10) for each task.

o For construction employers following Table 1, the descriptions 

must include the additional information necessary to fully and 

properly comply with Table 1, e.g., information regarding how 

to implement the controls as described on Table 1 or 

information on ensuring compliance with 29 CFR §

1926.1153(c)(2)(i)-(iii), as applicable. 

For example, where an employee is operating a crushing 

machine, the description of the control measures in the written 
52

exposure control plan should include information on how to 

operate and maintain the crushing machine in accordance with 

manufacturer’s instructions to minimize dust emissions (as 

specified in 29 CFR § 1926.1153(c)(1)(xvi)).

Another example would be where employees are engaged in a 

task on Table 1 that requires the use of wet methods, the 

description of the control measures should include instructions 

about applying water at flow rates sufficient to minimize 

release of visible dust, e.g., the appropriate flow rate in gallons 

per minute, as required by 29 CFR § 1926.1153(c)(2)(ii).

o The purpose of this requirement is to ensure that exposures to 

respirable crystalline silica hazards are consistently controlled.

• Description of housekeeping measures used to limit employee 

exposures, as provided by 29 CFR § 1910.1053(f)(2)(i)(C) and 29 

CFR § 1926.1153(g)(1)(iii). This requirement ensures that 

employers identify and implement appropriate cleaning methods 

such as HEPA-filtered vacuums, wet sweeping, and use of 

sweeping compounds to protect employees from respirable 

crystalline silica that can become airborne while performing 

housekeeping activities.

Ensuring safe housekeeping methods helps to consistently control 

exposures and hazards related to respirable crystalline silica. 

These housekeeping measures may encompass other types of work 

practices, for example:

o Maintaining exposed surfaces as free as practicable of 

silica-contaminated dust;

o Cleaning/emptying dust collection systems and dust 

disposal; and,

o Refraining from blowing or shaking silica-contaminated 

clothing to remove the dust that can contribute to employee 

exposures. 

• Under the construction standard, the ECP must include a 

description of procedures used to restrict access to work areas, 

when necessary, to minimize the number of employees exposed to 

respirable crystalline silica and their level of exposure, including 

exposure generated by other employers, as provided by 29 CFR §

1926.1153(g)(1)(iv). Restricting access is necessary where 

respirator use is required under Table 1 or an exposure assessment 
53

reveals that exposures are in excess of the PEL. The competent 

person may identify additional situations where limiting access is 

necessary.

o Employees on the work site not engaged in the task (for 

example, an employee directing traffic near a

jackhammering area), but still likely to be exposed to silica 

dust, must be protected from exposure by procedures for 

restricting access to any areas with high silica dust 

concentrations. 

• Acceptable procedures a construction employer can use to restrict

access include:

o Erecting permanent or temporary barriers around silicagenerating tasks;

o Posting signs or other warnings around silica-generating 

tasks;

o Scheduling high-exposure tasks when others will not be in 

the area; or 

o Directing employees to stay away from employees 

performing silica-generating tasks (see 81 FR at 16718, 

16803-04). The method(s) selected must be described in 

the written ECP.

g. Employers in general/maritime and construction industries could 

also consider including the following useful information in their 

ECP as applicable:

• A description of environmental factors such as weather (e.g., 

wind, humidity) and soil compositions (e.g., clay versus rock), 

and could also specify the location of the task, (e.g., task is 

performed in an enclosed space);

• Signs that indicate when controls are not working effectively, 

procedures used to verify whether the controls are working 

effectively, and schedules for conducting maintenance checks;

• A description of factors that affect exposures, such as types of 

silica-containing materials handled in those tasks (e.g., 

concrete, tile).

5. Inspection Guidelines. 

a. The CSHO should request and review the employer's written ECP 

to ensure that it includes each of the required elements. 
54

b. In construction, observed deficiencies in the plan and evaluation 

procedures should be discussed with the employer’s competent 

person to determine what previous efforts, if any, may have been 

made to evaluate how well the employer’s plan was working.

c. The plan must be tailored to cover the specific work tasks and 

practices in the workplace. The provisions listed in 29 CFR §

1910.1053(f)(2)(i)(A)-(C) and 29 CFR § 1926.1153(g)(1)(i)-(iv) 

must be included in the written ECP.

d. The CSHO should interview affected employees, including the 

competent person (for construction-related tasks), as part of the 

overall assessment of the employer’s ECP.

• Ask the employees if the ECP is made available to them for 

review.

• Ask the employer how often the written ECP is reviewed and 

evaluated for effectiveness.

• Ask the employer and employees if there were any revisions to the 

ECP.

e. Compliance with the ECP should be verified during the walkaround by personal observation and employee interviews. 

f. Questions asked during the interview should focus on determining 

how familiar the employee is with the ECP.

6. Citation Guidelines.

a. If the employer has no written ECP, cite 29 CFR §

1910.1053(f)(2)(i) or 29 CFR § 1926.1153(g)(1) as appropriate. 

b. If deficiencies as outlined in 29 CFR § 1910.1053(f)(2)(i)(A)-(C) 

and 29 CFR § 1926.1153(g)(1)(i)-(iv) are found in the employer’s 

ECP, cite the appropriate subparagraph(s).

c. Multiple deficiencies found during the inspection, especially longterm deficiencies, could indicate inadequate evaluation or 

updating. If the employer failed to review and evaluate the written 

ECP at least annually, cite 29 CFR § 1910.1053(f)(2)(ii) or 29 

CFR § 1926.1153(g)(2) as appropriate.

d. If the employer failed to make the written ECP readily available to 

employees, designated representatives, OSHA or NIOSH for 
55

examination and copying, cite 29 CFR § 1910.1053(f)(2)(iii) or 

29 CFR § 1926.1153(g)(3) as appropriate.

7. Competent Person (construction standard only). 29 CFR §

1926.1153(g)(4) requires the employer to designate a competent person to 

make frequent and regular inspections of job sites, materials, and 

equipment to implement the written ECP. There is no competent person 

requirement under the general industry/maritime standard; however, those

employers are not precluded from having such a person to administer the 

written ECP.

a. The competent person must have the knowledge and ability to 

perform the duties required in 29 CFR § 1926.1153(g)(4) and be 

familiar with, and capable of ensuring, that controls and other 

protections specified in the plan are implemented. For more 

information on the qualifications to be a competent person, see the 

definition of competent person discussed in Section IX.B.3.

b. The competent person must make routine observations such as 

visually evaluating dust generated from tasks being conducted. 

Where increases in visible dust occur, the competent person’s role

is to take prompt corrective action.

c. It is the responsibility of the competent person to make frequent 

and regular inspections of job sites, materials, and equipment for 

purposes of implementing the ECP and to identify existing and 

foreseeable respirable crystalline silica hazards in the workplace.

He/she is also responsible for ensuring implementation of the 

written ECP (i.e., ensuring engineering controls, work practice 

controls, required respiratory protection, housekeeping measures, 

and procedures to restrict access are implemented for the silicagenerating tasks listed in the plan).

Note: The standard does not define frequent and regular inspections or 

establish a set frequency to conduct worksite inspections. At a minimum, 

frequent and regular means sufficient to evaluate the effectiveness of the 

implementation of the written exposure control plan (e.g., to identify silica 

hazards and verify that effective control measures are being used). 

d. The frequency of inspections necessary to evaluate the 

implementation of a given plan can vary depending on a host of 

factors, such as the size of the worksite, the number of employees 

on the site, the complexity and diversity of the employer’s 

operations, and environmental conditions. 
56

• For example, in cases where the competent person is the only 

person on a jobsite, frequent inspections of the site would include

continuous assessment of variables associated with the job that the 

competent person is conducting (e.g., signs that the controls are not 

functioning effectively, a change in weather conditions that might 

require an adjustment of controls, or moving from an outdoor area 

to an enclosed area). Employers should remember that site 

assessment must be an ongoing process because of the changing 

environmental and work conditions encountered on construction 

job sites (see 81 FR at 16808).

e. There is no requirement that a competent person be present at a 

construction jobsite at all times. The competent person can leave 

the site periodically, so long as he or she fulfills the responsibilities 

in paragraph (g). The competent person must make sufficient

inspections to identify situations that could result in hazardous 

conditions (e.g., indications of failure of engineering controls), and 

ensure that corrective measures are taken. Therefore, the 

conditions at each individual worksite will dictate whether a

competent person is needed at the jobsite at all times.

f. The competent person must be a person who is qualified and 

retains the accountability and responsibility for the day-to-day

implementation of the written ECP for the site under his/her 

control.

g. The identity of the competent person is not required to be listed in 

the written ECP. However, employees must be able to identify the 

competent person, and 29 CFR § 1926.1153(i)(2)(i)(E) requires 

each employee covered by standard to be trained on the identity of 

the competent person. 

8. Inspection Guidelines. 

A competent person is required to implement the written ECP and to 

ensure that controls are functioning effectively. The extent of training or 

experience required for the competent person could vary based on the 

complexity of the hazards in the worksite. CSHOs should conduct 

interviews to assess whether the competent person(s) has the knowledge to 

implement the ECP and is familiar with the engineering controls, work 

practices, respiratory protection, and housekeeping methods for the 

worksite, and whether they have actually implemented the ECP. The 

CSHO should:

• Ask the employer and employees the identity of the competent 

person(s) on a jobsite;
57

• Ask the employer and employees how often the competent person 

conducts inspections of the site, materials, equipment and what

those inspections involve;

• Ask the identified competent person how often he or she conducts 

inspections of the site, materials, equipment and what those 

inspections involve;

• Ask the employer and the competent person about his or her 

knowledge and ability related to implementing the ECP (based on 

level of training, education and work experience);

• Ask the competent person about the tasks involving silica exposure 

and how the employer controls them;

• Ask the competent person how he or she determines that controls 

are working;

• Ask the competent person how the employer restricts access to 

high-exposure areas; and

• Ask the competent person about authority to promptly correct or 

eliminate silica hazards.

9. Citation Guidelines. 

An employer’s failure to designate a competent person, or an employer’s 

designation of a competent person who is not qualified, or if a competent 

person fails to conduct frequent and regular inspections of jobsites,

materials, and equipment to implement the ECP, cite 29 CFR §

1926.1153(g)(4).

10. Abrasive blasting. 29 CFR § 1910.1053(f)(3) and 29 CFR § 

1926.1153(d)(3)(ii) require the employer to comply with other OSHA 

standards, if applicable, when performing abrasive blasting operations 

using crystalline silica-containing blasting agents or where abrasive 

blasting is conducted on substrates that contain crystalline silica. 

Examples of such OSHA standards include:

a. Ventilation standards, 29 CFR § 1910.94 and 29 CFR § 1926.57,

which require the employer to keep the concentration of respirable 

dust in the breathing zone of the abrasive-blasting operator below 

the levels specified in 29 CFR § 1910.1000 or 29 CFR § 1926.55

for operations where abrasive blasting of coated materials may 

create exposures to hazardous dusts. 
58

b. Mechanical Paint Removers, 29 CFR § 1915.34, which requires 

employers to provide eye and respiratory protection to employees 

working in areas where unsafe concentrations of abrasive materials 

and dusts are present or as per 29 CFR § 1915 Subpart Z.

c. Personal Protective Equipment, 29 CFR § 1915 Subpart I, which 

requires employers to perform a hazards assessment to determine 

what hazards are present, and provide workers with the appropriate 

PPE to protect them from the hazard(s) identified.

Note: Where an alternative abrasive material not containing silica (e.g., 

steel shot, glass beads) is used, also evaluate for any hazards associated 

with the material.

11. Inspection Guidelines.

a. The CSHO should observe and evaluate an employer’s abrasive 

blasting operation for compliance with applicable OSHA 

standards. In addition to the inspection guidelines listed 

throughout this directive, the specific instructions below apply to 

inspections of abrasive blasting operations where crystalline silicacontaining blasting agents are being used, or where abrasive 

blasting is conducted on substrates that contain crystalline silica.

b. The air-sampling device, such as a cyclone, needs to be placed 

within the breathing zone (6-9 inch radius), outside any protective 

equipment (including the abrasive blasting respirator).

c. When conducting an inspection, a CSHO should:

• Conduct monitoring to determine employee exposure to metals, 

such as lead, arsenic, beryllium, manganese, chromium, cadmium, 

copper, and magnesium. (Abrasive blasters may be exposed to 

metals either from the surface being blasted or from non-silica 

abrasive media). The CSHO should review the safety data sheet 

for the abrasive blasting media to determine the content;

• Conduct exposure monitoring of potentially exposed employees 

not engaged in abrasive blasting but still working close to the 

blasting operation;

• Conduct noise exposure monitoring inside the hood, appropriate to 

evaluate compliance with OSHA’s Noise standard, 29 CFR §

1910.95 or 29 CFR § 1926.52;

• Determine whether the ventilation systems for abrasive blasting 
59

rooms and containment structures prevent escape of dust and 

provide prompt clearance of dust-laden air;

• Determine whether each blast cleaning nozzle is properly equipped 

with an operating valve that must be held open manually;

• For supplied-air respirators, evaluate breathing air quality and use. 

For oil-lubricated compressors, ensure that the compressor is 

equipped with a high-temperature or carbon monoxide alarm, or 

both, to ensure that carbon monoxide levels remain below 10 parts 

per million (ppm). See 29 CFR § 1910.134, paragraph (i) –

Breathing air quality and use;

Note: Using an abrasive blasting hood while wearing a filtering face piece 

respirator voids the NIOSH-approval certification for both respirators. 

• When compressors are used to supply air, ensure that in-line 

absorbent beds are used and maintained;

• Review electrical grounding;

• Review pressure controls;

• Determine whether the abrasive blasters have adequate PPE, such 

as canvas or leather gloves and aprons, to protect against injury 

from material impact; and

• Where an alternative abrasive material is being used that does not 

contain crystalline silica, such as glass beads, steel grit and shot, 

sawdust, and shells, ensure that an appropriate evaluation of the 

hazards associated with the material has been conducted. 

12. Citation Guidelines:

a. If overexposures to metals or noise are found, then cite the

applicable paragraph(s) in the appropriate air contaminant or noise 

standard.

b. If the ventilation system for a blast cleaning enclosure is found to 

be inadequately designed or ineffective at controlling dust, then the 

applicable section of 29 CFR § 1910.94(a) or 29 CFR § 1926.57 

should be cited and grouped with 29 CFR § 1910.1053(f)(3) or 29 

CFR § 1926.1153(d)(3)(ii), as well as 29 CFR § 1910.1053(f)(1) or

29 CFR § 1926.1153(d)(3)(i), as applicable.
60

c. If blast cleaning nozzles are not properly equipped with operating 

valves that must be held open manually, then 29 CFR § 

1910.244(b) or 29 CFR § 1926.302(b)(10) should be cited.

d. For violations related to respiratory protection for abrasive blasting 

operations, cite under 29 CFR § 1910.94(a)(5) and group with the 

applicable sections of 29 CFR § 1910.134, as well as 29 CFR § 

1910.1053(g) or 29 CFR § 1926.1153(e).

e. For violations related to personal protective equipment (PPE), cite

under 29 CFR §§ 1910.94(a)(5), 1910.132, 1915.34, 1926.28, 

1926.95, or 29 CFR §§ 1926.100-103, as appropriate, grouped with 

29 CFR § 1910.1053(f)(3) or 29 CFR § 1926.1153(d)(3)(ii), as 

applicable.

H. Respiratory Protection.

1. 29 CFR § 1910.1053(g) and 29 CFR § 1926.1153(e) establish 

requirements for respiratory protection.

a. Where respiratory protection is required by the Silica standards, 

29 CFR § 1910.1053(g)(1) and 29 CFR § 1926.1153(e)(1) require 

employers to provide employees with appropriate respiratory 

protection that complies with the requirements of these paragraphs 

and OSHA’s Respiratory Protection standard, 29 CFR § 1910.134.

b. Where respirator use is required, 29 CFR § 1910.1053(g)(2) and 29 

CFR § 1926.1153(e)(2) require the employer to institute a 

respiratory protection program in accordance with 29 CFR § 

1910.134. 

c. In general industry and maritime, respiratory protection is required

in the following situations:

• Where exposures exceed the PEL during periods necessary to 

install or implement feasible engineering and work practice 

controls;

• Where exposures exceed the PEL during tasks, such as certain

maintenance and repair tasks, for which engineering and work 

practice controls are not feasible;

• During tasks for which an employer has implemented all feasible

engineering and work practice controls and such controls are not 

sufficient to reduce exposures to or below the PEL; and,
61

• During periods when the employee or designated representative is 

in a regulated area.

d. In construction, respiratory protection is required:

• Where specified by Table 1 and

• Where exposures exceed the PEL either during tasks not listed on 

Table 1 or where the employer does not fully and properly 

implement the engineering controls, work practices, or respiratory 

protection described on Table 1. Such as:

o Where exposures exceed the PEL during periods necessary to 

install or implement feasible engineering and work practice 

controls;

o Where exposures exceed the PEL during tasks, such as certain 

maintenance and repair tasks, for which engineering and work 

practice controls are not feasible; and

o During tasks for which an employer has implemented all 

feasible engineering and work practice controls and such 

controls are not sufficient to reduce exposures to or below the 

PEL.

2. The respiratory protection standard includes APFs (see 29 CFR §

1910.134(d)(3)(i)(A) outlined on Table 1- Assigned Protection Factors). 

The APF table shows the level of respiratory protection that a given 

respirator or class of respirators is expected to provide when the users are 

properly fitted and trained, and the employer has implemented a 

continuing, effective respiratory protection program. 

3. 29 CFR § 1926.1153(e)(1) requires employers to provide each employee 

the appropriate respirator under § 1910.134. For tasks listed on Table 1, if 

the employer fully and properly implements the engineering controls, 

work practices, and respiratory protection specified on Table 1, the 

employer is considered in compliance with paragraph (e)(1). See 29 CFR 

§ 1926.1153(c)(1) and paragraph (c)(3).

4. Construction employers who perform tasks not listed on Table 1, or do not 

fully and properly implement the controls described on Table 1, have to 

comply with the requirements under 29 CFR § 1910.134(d)(1) and 

paragraph (d)(3) where exposures exceed the PEL.

5. 29 CFR § 1910.134(e)(6)(i)(A) requires employers to obtain a written 

recommendation from the PLHCP regarding the employee’s ability to use 

a respirator. If an employee receives medical surveillance under the silica 
62

standard, the PLHCP’s written medical opinion for the employer also must 

include any recommended limitations on the employee’s use of 

respirators. See 29 CFR § 1926.1153(h)(6)(i)(C), as well as 29 CFR

§ 1910.1053(i)(6)(i)(C).

6. If a PLHCP determines through either a medical evaluation under the 

respiratory protection standard, or medical surveillance under the silica 

standard, that an employee’s health is at increased risk if a negative 

pressure respirator is used, but the employee can use a powered air 

purifying respirator (PAPR), then the employer must provide a PAPR (see 

29 CFR § 1910.134(e)(6)(ii)).

7. Where the silica standards require respiratory protection, OSHA’s 

respiratory protection standard requires the employer to provide a medical 

evaluation to determine the employee’s ability to use a respirator before fit 

testing and use. See 29 CFR § 1926.1153(e)(1), (e)(2); 29 CFR §

1910.1053(g)(1), (g)(2); and 29 CFR § 1910.134(e). Regardless of 

whether an employee refuses medical surveillance, an employee may 

perform silica exposure tasks that require respirator use only if they

undergo the medical evaluation required by the Respiratory Protection 

standard and is cleared to wear a respirator. 

8. Inspection Guidelines. 

a. Verify that the employer has established and implemented an 

appropriate respiratory protection program that contains all the 

required elements. Review the employer’s written program, make 

observations during a walk-around, and conduct employee 

interviews.

b. Evaluate whether respiratory protection is being used when 

required. CSHOs should also review the employer’s ECP to verify 

whether it includes a description of the respiratory protection used 

to limit employee exposure to respirable crystalline silica for each 

task.

c. Evaluate the adequacy of respiratory protection based on an 

exposure assessment by the employer or the CSHO when exposure 

exceeds the PEL.

d. The APF of the respirator used must be high enough to maintain

the employee’s exposure to respirable crystalline silica at or below 

the Maximum Use Concentration (MUC) (e.g., the product of 

multiplying the APF of the respirator by the PEL for silica) (see

29 CFR § 1910.134(d)(3)(i)(B)(1)).

e. Review medical evaluation results that are authorized under the 
63

respiratory protection standard (29 CFR § 1910.134(e)) and the 

PLHCP or specialist’s written medical opinion for the employer 

and conduct interviews to determine whether there are any 

employees wearing respirators who should not be. 

f. Determine if the requirements of 29 CFR § 1910.134(e) are being 

met by interviewing a number of employees and asking whether 

they have been provided with a confidential evaluation of their 

ability to wear a respirator.

g. For guidance on inspection procedures for 29 CFR § 1910.134, 

refer to the Inspection Procedures for the Respiratory Protection 

Standard compliance directive (CPL 02-00-158), June 26, 2014. 

9. Citation Guidelines.

29 CFR § 1910.1053(g)(2) and 29 CFR § 1926.1153(e)(2) require

employers to comply with the respiratory protection standard when 

respirators are required by the silica standards.

a. If the employer does not provide appropriate respiratory protection 

for employees in the above situations, cite the applicable 

subparagraphs of 29 CFR § 1910.1053(g)(1) or 29 CFR § 

1926.1153(e)(1) and group with the applicable provision of the 

respiratory protection standard, as appropriate.

• For example, when a general industry/maritime employer has 

provided a respirator that does not maintain an employee’s 

exposure to respirable crystalline silica at or below the MUC (or

does not provide a respirator at all), 29 CFR § 1910.1053(g)(1) 

should be cited and grouped with the applicable provisions under

29 CFR § 1910.134(d)(3)(i)(B)(1). 

Likewise, if a construction employer commits the same violation, 

29 CFR § 1926.1153(e)(1) should be cited and grouped with the 

applicable provisions under 29 CFR § 1910.134(d)(3)(i)(B)(1). 

b. If a construction employer is not providing respiratory protection 

as specified on Table 1, but has otherwise implemented the other 

controls specified on Table 1, CSHOs should cite for noncompliance with 29 CFR § 1926.1153(e) and group with

29 CFR § 1926.1153(c)(1), (d)(1) where there is exposure above 

the PEL. CSHOs have to show that 29 CFR § 1926.1153(e)(1)(ii) 

applies to establish a violation of 29 CFR § 1926.1153(e)(1)(ii)(A), 

(B), and/or (C).
64

c. If employees are required to wear respirators, employers are 

required to have a written respiratory protection program. If the 

employer has not implemented the program or elements of it are 

deficient or missing, CSHOs should cite 29 CFR §

1910.1053(g)(2) or 29 CFR § 1926.1153(e)(2), as appropriate,

grouped with 29 CFR § 1910.134(c).

• If program elements are deficient or missing, CSHOs shall group 

where appropriate and cite the applicable subparagraphs under 29 

CFR § 1910.134.

d. If there is a discrepancy between the written respiratory protection 

program and work practices implemented for use of respirators at 

the work site, cite 29 CFR § 1910.1053(g)(2) or 29 CFR § 

1926.1153(e)(2) and group with applicable paragraphs under 29 

CFR § 1910.134(d)-(m).

Note: All employers covered by the standards, including those employers 

following Table 1, must still comply with all provisions of 29 CFR §

1910.134, as applicable. This means workers wearing respirators must be 

medically evaluated, fit-tested, and trained, and the employer must ensure 

proper use and maintenance of the respirators where needed.

I. Housekeeping Practices:

1. 29 CFR § 1910.1053(h)(1) and 29 CFR § 1926.1153(f)(1) prohibit dry 

sweeping and dry brushing where such activities could contribute to 

employee exposures to respirable crystalline silica unless wet sweeping, 

HEPA-filtered vacuuming, or other methods that minimize the likelihood 

of exposure are not feasible. An employer alleging infeasibility must 

demonstrate that no alternative method that minimizes the likelihood of 

exposure is feasible.

Note: The term “dry brushing” as used in the Silica standards is intended 

to restrict dry brushing activity that is comparable to dry sweeping, such 

as using a brush as a tool to clean clothing or surfaces. The standards do 

not prohibit employees from using their hands to remove small amounts of 

visible dust from their clothing.

a. The limited infeasibility exceptions included in these housekeeping 

provisions are intended to encompass situations where wet 

methods, HEPA-filtered vacuuming, and other exposureminimizing methods are not effective, would cause damage, or 

would create a hazard in the workplace. See 81 FR at 16795-96.

• An employer can establish infeasibility for these purposes by 
65

demonstrating that wet sweeping, using a HEPA-filtered vacuum, 

and other methods that minimize the likelihood of exposure would 

negatively impact the quality of the work being done, would not be 

effective, would cause damage, or would create a hazard in the 

workplace. However, even in cases where one of the acceptable 

cleaning method may not be feasible, employers may be able to 

use another acceptable cleaning method (see GI FAQ #37).

• For example, wet sweeping may be infeasible where water comes

into contact with molten metal and creates an explosion hazard.

However, an employer that could not wet sweep may be able to 

use another acceptable cleaning method, e.g., HEPA-filtered 

vacuuming. In order to dry sweep or dry brush, the employer 

would need to show that no alternative methods are feasible.

b. The proper use of commercially-available dust-suppression 

sweeping compounds (e.g., oil or wax based) in accordance with 

the manufacturer’s instructions is a cleaning method that 

minimizes the likelihood of exposure for purposes of 29 CFR §

1926.1153(f)(1) and 29 CFR § 1910.1053(h)(1), and therefore, is 

an acceptable dust suppression housekeeping cleaning method 

under the standard (see GI FAQ #38, CON FAQs #26 and #27).

c. Some commercially-available dust-suppression sweeping 

compounds contain quartz silica. If an employer use such 

compounds, the CSHO should review the compound’s safety data 

sheet (SDS) and evaluate the dry sweeping operations. If the 

CSHO determines that the compound was used properly and it 

effectively suppresses the generation of respirable dust during dry 

sweeping or dry brushing, (i.e., the sweeping activity does not 

appear to contribute to airborne dust exposure), then the use of the 

silica-containing sweeping compound would not be subject to the 

housekeeping restrictions in the silica standard (see GI FAQs #38 

and #39 and CON FAQs #26 and #27).

d. Some general industry employers (e.g., foundries) use drivable 

powered industrial sweepers to clean dust. These sweepers are

equipped with rotating brushes that lift dust from the floor and feed 

the dust into a vacuum located on the underside of the 

equipment. When these types of sweepers are equipped with 

HEPA filters and effectively remove the dust, their use is

considered “HEPA-filtered vacuuming” for purposes of 

29 CFR § 1910.1053(h)(1) of the standard. When these sweepers 

are not equipped with HEPA filters, their use is considered an 

“other” acceptable housekeeping method when they are operated 

and maintained properly so as to minimize the likelihood of 
66

employee exposure. CSHOs should evaluate the employer’s ECP 

to ensure that the employer has assessed exposures related to use 

of these sweepers (see GI FAQ #36).

Note 1: For all such drivable powered industrial sweepers (HEPA or nonHEPA), the employer using these type of sweepers must ensure 

compliance with all applicable provisions of the silica standard, including

reducing exposures to or below the PEL. 

Note 2: Notwithstanding vacuums on the sweepers described above, the 

use of a non-HEPA filtered vacuum for housekeeping would not be 

considered an “other [housekeeping] method” because it does not 

minimize the likelihood of exposure. OSHA discourages cleaning with 

non-HEPA-filtered vacuums because respirable particles discharged 

through the vacuum’s exhaust into the immediate work area could 

contribute to employees’ silica exposures. If fugitive dust from nonHEPA-filtered vacuuming or other discharge from vacuums contributes to 

employee exposures that exceed the PEL, the employer would need to 

follow the hierarchy of controls to reduce and maintain exposures to or 

below the PEL in accordance 29 CFR § 1910.1053(f)(1) and 29 CFR §

1926.1153(d)(3). Typically, an employer’s use of such non-HEPAfiltered vacuums would necessitate employee exposure assessment.

When a housekeeping method is reasonably expected to result in 

exposures at or above the AL, the employer must comply with exposure 

assessment requirements and other applicable provisions of the standard. 

e. Employers must ensure that vacuum system filters and dust are

handled so as to minimize worker exposures to silica dust. This 

could involve disposing of filters and dust in sealed containers, 

such as heavy-duty plastic bags, to prevent the release of dust. 

Employers must also ensure that filter cleaning and dust disposal 

are covered in their written exposure control plans, when required 

by 29 CFR § 1910.1053(f)(2)(i) and 29 CFR § 1926.1153(g)(1)(i).

Note 3: Some vacuum system filters must be cleaned manually, while 

others have automatic filter-cleaning mechanisms.

f. Employers are prohibited from using compressed air to blow clean 

clothing or surfaces where that activity can contribute to employee 

silica exposures, unless it is used in conjunction with a ventilation 

system that effectively captures the dust cloud created by the 

compressed air, or no alternative method is feasible. See

29 CFR § 1910.1053(h)(2)(i)-(ii) and 29 CFR § 1926.1153(f)(2)(i)-

(ii). 
67

g. OSHA expects that employers will typically be able to use an 

alternative cleaning method or compressed air with an appropriate 

ventilation system; the circumstances in which ventilation systems 

cannot be used and no other alternative method is feasible are rare. 

It is the employer’s burden to show that it cannot use a ventilation 

system with the compressed air or that no alternative method is 

feasible (see GI FAQ #42).

h. Employers are not prohibited from using compressed air for

purposes other than cleaning clothes or surfaces, e.g., for operating 

a pneumatic tool. 

2. Inspection Guidelines. 

a. Review the employer’s written ECP to ensure that the employer’s 

housekeeping practices are included and properly implemented. 

b. Interview employees regarding housekeeping practices and

observe employees’ housekeeping activities when possible. 

CSHOs should use videos and/or photographs to document when 

permissible housekeeping methods are not used.

c. If possible, observe the handling of cleaning equipment, such as 

HEPA-filtered vacuums. Employers should have procedures to 

clean and/or replace vacuum filters in a way that minimizes

exposures.

d. If compressed air is used to clean surfaces or clothing, CSHOs

should determine whether it is being used in conjunction with a 

ventilation system. The standard does not specify the use of a 

particular ventilation system for these purposes. Whatever type of 

supplementary ventilation system is used, it must be able to

effectively capture any dust cloud created by the compressed air to 

prevent dust from entering employees’ breathing zones and

contributing to silica exposures (see GI FAQs # 43).

e. If the CSHOs believe there could be exposures exceeding the AL 

or PEL during housekeeping activities, they should collect

personal air samples. The CSHO may also collect a bulk sample to

support documentation that the dust contains crystalline silica.

f. If employees are using compressed air without a ventilation system 

to clean clothes or surfaces and it appears that it could contribute to 

employee exposure, CSHOs should determine whether any other 

alternative cleaning method is feasible. Gather evidence on

feasibility of other cleaning methods (e.g., wet sweeping, HEPA-
68

filtered vacuuming, and using compressed air in conjunction with 

an adequate ventilation system).

g. An employer shall not allow dry sweeping or dry brushing, unless 

wet sweeping, HEPA-filtered vacuuming or other methods that 

minimize the likelihood of exposure are not feasible. An employer 

may establish infeasibility for these purposes by providing evidence 

that wet sweeping, using a HEPA-filtered vacuum, and other methods 

that minimize the likelihood of exposure would negatively impact the 

quality of the work being done (see GI FAQ #37).

3. Citation Guidelines. 

a. 29 CFR § 1910.1053(h)(1) or 29 CFR § 1926.1153(f)(1) should be 

cited where:

• Dry sweeping or dry brushing is used for cleaning where such 

activity could contribute to employee exposure to respirable 

crystalline silica; and

• The employer cannot demonstrate that wet sweeping, HEPAfiltered vacuuming, or other cleaning methods that minimize the 

likelihood for exposure to respirable crystalline silica are 

infeasible.

b. 29 CFR § 1910.1053(h)(2) or 29 CFR § 1926.1153(f)(2) should be 

cited where:

• Compressed air is used to clean clothing or surfaces where such 

activity could contribute to employee exposure to respirable 

crystalline silica; 

• The compressed air is being used without a ventilation system that 

effectively captures the dust cloud it creates; and 

• The employer cannot demonstrate that wet sweeping, HEPAfiltered vacuuming, or other cleaning methods that minimize the 

likelihood of exposure are infeasible.

J. Medical Surveillance.

1. General Information. 29 CFR § 1910.1053(i) and 29 CFR § 1926.1153(h) 

set forth requirements for the provision of medical surveillance:

a. For general industry/maritime, 29 CFR § 1910.1053(i)(1)(i) 

requires medical surveillance to be made available to each 
69

employee who will be exposed to respirable crystalline silica at or 

above the AL for 30 or more days per year. 

Note: From June 23, 2018, until June 22, 2020, the medical surveillance 

trigger in general industry is exposure above the PEL for 30 or more days 

per year. Beginning June 23, 2020, the medical surveillance trigger in 

general industry is exposure at or above the AL for 30 or more days per 

year.

b. For construction, 29 CFR § 1926.1153(h)(1)(i) requires medical

surveillance to be made available to each employee who will be

required to wear a respirator by the silica standard for 30 or more 

days per year. 

Note: Any partial day of respirator use (e.g., even if for only one hour or 

less) is considered one day of respirator use.

• The 30-day trigger applies to each individual employer, not the 

total number of days per year worked by the employee for multiple 

employers. Respirator use with past employers does not count 

towards the 30-day trigger. Employers must anticipate the number 

of days that the employee will be required to wear a respirator 

under the silica standard while employed by that particular 

employer.

c. 29 CFR § 1910.1053(i)(1)(i) and 29 CFR § 1926.1153(h)(1)(i) also 

require employers to make medical surveillance, including 

referrals to specialists, available at no cost to the employee and at a 

reasonable time and place. 

• If medical surveillance requires travel away from the work site, the 

employer must bear the cost of travel. Employees must be paid for 

time spent undergoing a medical examination and any tests, 

including travel time.

d. Medical surveillance under both standards must be performed by a 

PLHCP as defined by 29 CFR § 1910.1053(b) and 29 CFR §

1926.1153(b), per 29 CFR § 1910.1053(i)(1)(ii) and 29 CFR § 

1926.1153(h)(1)(ii).

2. Timing and Frequency.

a. 29 CFR § 1910.1053(i)(2) and 29 CFR § 1926.1153(h)(2) require 

employers to make available medical examinations within 30 days 

after initial assignment to all employees who meet the trigger for 

medical surveillance, unless the employee has received a medical 
70

examination in accordance with the standard within the past 3 

years.

b. 29 CFR § 1910.1053(i)(3) and 29 CFR § 1926.1153(h)(3) require 

employers to make medical exams available at least every three 

years, or more frequently if recommended by the PLHCP, for 

employees who meet the trigger for medical surveillance under 29 

CFR § 1910.1053(i)(1)(i) or 29 CFR § 1926.1153(h)(1)(i).

Note: A PLHCP might recommend more frequent medical examinations 

based on factors such as high exposure levels or a medical finding (e.g., an 

X-ray suggesting silicosis).

c. An exam by a specialist must be made available within 30 days 

after the employer receives a PLHCP's written medical opinion 

that recommends that examination. See 29 CFR § 1910.1053(i)(7) 

and 29 CFR § 1926.1153(h)(7).

d. When an employer has previously determined that an employee 

does not require medical surveillance because his or her exposure 

is not anticipated to meet the trigger(s) outlined in Sections 

IX.J.1.a or b of this Instruction, but a change in process or task, or 

modification in the frequency of a process or task occurs such that 

the employee’s exposure exceeds the trigger for medical 

surveillance, then the exam shall be made available as soon as the 

employer realizes that the trigger will be met.

e. Employers are required to ensure that the employee receives a 

copy of the written medical opinion. See 29 CFR §

1910.1053(i)(6)(iii) and 29 CFR § 1926.1153(h)(6)(iii). The

employer may accept a copy of a written opinion as proof of prior 

medical surveillance for exposures to respirable crystalline silica.

f. Employers are generally not required to consider a newly-hired 

employee’s silica exposure experience with any former employer 

within the previous 12 months when determining whether the new 

employee must be offered medical surveillance. Except as 

described in Section IX.J.2.d above, the medical surveillance 

trigger is based on the anticipated exposure at each particular 

employer’s establishment(s). However, the trigger for medical 

surveillance would apply when an employer hires a particular 

employee for any time during a 12-month period, whether 

continuous or intermittent, and that employee’s assignments result 

in cumulative silica exposure exceeding a medical surveillance 

trigger, as described above.

• Example: If a construction employer intermittently hires the same 
71

employee several times throughout a 12-month period, the 

employer must consider all the days the employee wears (or is 

expected to wear) a respirator during that year to determine 

whether the employee meets the medical surveillance trigger and 

must offer medical surveillance as soon as it appears that the 

employee might meet the trigger.

3. Components of the Medical Surveillance Examination.

a. 29 CFR § 1910.1053(i)(2) and 29 CFR § 1926.1153(h)(2) include 

the required components of the initial (baseline) examination. The 

exam must consist of the following:

• A medical and work history including special emphasis on the 

employee’s past, present, and anticipated exposure to silica, dust, 

and other agents that affect the respiratory system; history of 

respiratory system dysfunction, including signs and symptoms of 

respiratory diseases (e.g., shortness of breath, cough, wheezing), 

history of tuberculosis (TB), and smoking status and history;

• A physical examination with special emphasis on the respiratory 

system; 

• A chest X-ray (interpreted and classified by a NIOSH-certified Breader). For a listing of certified B-readers, medical providers 

should visit NIOSH’s website at: 

https://www.cdc.gov/niosh/topics/chestradiography/breaderlist.html;

Note: While X-rays can be read remotely, some States require B-readers 

to be medically licensed in the State in which the X-rays are read. The 

responsibility lies with the employer to ensure that a NIOSH-certified Breader is used. 

• A pulmonary function test administered by a spirometry technician 

with a current certificate from a NIOSH-approved spirometry 

course. For a listing of NIOSH-certified spirometry courses, 

medical providers should visit NIOSH’s website

at: https://www.cdc.gov/niosh/topics/spirometry/approvedcourse.html;

Note: All providers, including physicians, must complete the NIOSHapproved spirometry training and maintain a current certificate before they 

can perform the pulmonary function test under the silica standards.

• Testing for latent TB infection; and,
72

• Any other tests deemed appropriate by the PLHCP.

Note: Exposure to respirable crystalline silica increases the risk for 

developing active pulmonary TB infection in individuals with latent TB 

infection. Employees who tested positive for latent TB infections are not 

contagious, but treatment to prevent development of active TB is essential. 

Therefore, the PLHCP should refer the TB positive employee to the local 

public health department as required by state law.

4. Other Medical Surveillance Requirements.

a. Periodic examinations. As explained above, periodic examination 

must be made available at least every 3 years or more frequently if 

recommended by the PLHCP for employees who meet the trigger 

for medical surveillance. The periodic examination shall include 

all the components of the initial examination noted above except 

the testing for latent TB infection. See 29 CFR § 1910.1053(i)(3) 

and 29 CFR § 1926.1153(h)(3).

b. Information provided to the PLCHP or specialist. 29 CFR §§

1910.1053(i)(4), 1910.1053(i)(7)(ii), 1926.1153(h)(4), and 

1926.1153(h)(7)(ii) require the employer to ensure that the PLHCP 

or any specialist has a copy of the standard and the following 

information:

• A description of the employee’s former, current, and anticipated 

duties and levels of exposures as they relate to respirable 

crystalline silica;

• A description of any PPE used or to be used by the employee, 

including when and for how long the employee has used or will 

use that equipment; and

• Information from records of employment-related medical 

examinations previously provided to the employee that are 

currently within the employer’s control.

c. Written Medical Opinion. 29 CFR §§ 1910.1053(i)(6),

1910.1053(i)(7), 1926.1153(h)(6), and 1926.1153(h)(7) require 

employers to obtain a written medical opinion from the PLHCP or 

specialist within 30 days of the examination and to ensure the 

employee receives a copy of the written medical opinion within 30 

days of the exam. The medical opinion must contain only the date 

of the exam, a statement from the PLHCP that the exam met the 

requirements of the standard (not applicable to specialists), and any 

recommended limitations on the employee’s use of respirators.
73

If the employee provided the PLHCP or specialist with written

authorization, then the written medical opinion for the employer 

shall also contain any recommended limitations on the employee’s 

continued exposure to silica, and for non-specialists, any 

recommendation that the employee should be referred to a 

specialist (see CON FAQ #47). The silica standard made the 

release of this information dependent on the employee’s 

authorization to protect employee privacy and encourage 

employees to participate in medical surveillance by minimizing 

fears about retaliation or discrimination based on medical findings. 

Appendix B to the silica standards includes templates for the 

written medical report, the written medical opinion, and the written 

authorization.

Note 1: CSHOs should be aware that the PLHCP and specialist’s written 

opinion for the employer under the Silica standards differs from that in 

OSHA’s previous substance-specific standards. The difference is that the 

employee must provide written authorization for the release of certain 

information. Under other health standards, there is no employee 

authorization required. 

Note 2: The standards also require the employer to ensure that the PLHCP 

or specialist explains to the employee the results of the medical 

examination and provides each employee with a written medical report

within 30 days of each medical examination performed. The written 

medical report contains more medical information than the written 

medical opinion for the employer and is intended under the silica 

standards to be provided only to the employee. See 29 CFR §§

1910.1053(i)(5), (i)(7)(iii), and 1926.1153(h)(5), (h)(7)(iii).

Note 3: If an employer wishes to document an employee’s decision to 

decline a medical examination, the employer could ask the employee to 

sign a statement affirming that he or she was offered medical surveillance, 

but declined to participate. If an employee declines a medical evaluation 

under the respiratory protection standard, then the employer may not 

assign him or her a task requiring respirator use (see GI FAQ 49).

5. Inspection Guidelines.

a. The CSHO should determine whether the employer has included 

the appropriate employees in the medical surveillance program. 

For example, CSHOs should review the employer’s exposure 

assessment and interview employees to determine whether the 

employer provided a medical exam.
74

b. The CSHO should ask employees about their exposures, respirator 

usage, entry into regulated areas, and if they were offered medical 

examinations by their employer. Appendix E of this Instruction 

contains a suggested health questionnaire for CSHOs to use.

CSHOs should conduct interviews to determine:

• If the examination took place prior to or within 30 days of 

beginning the silica work assignments; or

• If examinations are offered at no cost, if employees are paid for 

time spent taking examinations, if the employer pays the cost of 

travel (if any), and if medical testing is offered at reasonable times 

and places;

• If the PLHCP or specialist explained the results of the examination 

and provided a written medical report;

• If the employee received a copy of the written medical opinion, 

either from the employer or from the PLHCP or specialist;

• If the employer has not offered medical surveillance in general 

industry/maritime establishments, CSHOs should ask employees 

about the types and frequency of tasks performed. In the

construction context, CSHOs should determine how often 

employees perform tasks requiring respirator use to determine 

whether they should have been offered medical surveillance; and

• If the PLHCP recommends that the employee see a specialist and 

the employee authorizes the inclusion of the recommendation in 

the written medical opinion for the employer, CSHOs should ask 

the employee whether the employer offered any additional

examinations.

c. If the employee has previously declined a medical examination, an 

employer may choose to have the employee sign a statement that 

he or she was offered the exam(s), but declined to participate. 

However, the employer must continue to offer a medical 

examination to each employee who meets the trigger for medical 

surveillance if the employee requests it, or, at a minimum, the next 

time an examination is due (i.e., within three years). 

d. The silica standards require employers to make and maintain 

accurate records for each employee covered by medical 

surveillance in accordance with 29 CFR § 1910.1053(k)(3) and 29 
75

CFR § 1926.1153(j)(3). These records include a copy of the 

PLHCP and specialist’s medical opinion(s). CSHOs should ask 

the employer to provide copies of the medical surveillance records 

including the medical opinions. See Section IX.L Recordkeeping.

• Whenever reviewing medical reports or opinions, the CSHO

should follow OSHA Instruction CPL 02-02-072, Rules of Agency 

Practice and Procedure Concerning OSHA Access to Employee 

Medical Records, Aug. 22, 2007.

• Medical records are often kept at a medical provider’s office. To 

verify the content of any medical report that is not available onsite, CSHOs may need to contact the medical provider.

• For assistance with obtaining a medical access order (MAO) to 

access employee medical records, communication with healthcare 

providers, review of the medical surveillance examinations, and 

interpretation of examination results, contact the Office of 

Occupational Medicine and Nursing (OOMN) in the National 

Office. Consider issuing a subpoena for medical records, as 

necessary.

e. CSHOs may contact PLHCPs and specialists to determine whether 

the employer provided them with the information required by the 

standards.

6. Citation Guidelines. 

a. If medical surveillance was not made available to employees at no 

cost, and at a reasonable time and place, by general 

industry/maritime employers in accordance with 29 CFR § 

1910.1053(i), or by construction employers in accordance with 29 

CFR § 1926.1153(h), the appropriate subparagraph(s) should be 

cited.

b. Cite 29 CFR § 1910.1053(i)(1)(i) if no medical surveillance was 

made available where general industry/maritime employees were

exposed at or above the AL for 30 or more days a year beginning 

June 23, 2020 (or above the PEL for 30 or more days per year from 

June 23, 2018-June 22, 2020). 

c. Likewise, cite 29 CFR § 1926.1153(h)(1)(i) for construction 

employees if no medical surveillance was made available when the 

employee was required to wear a respirator by the silica standard 

for 30 or more days a year. These citations may be supported 

through employer and employee statements regarding levels of 
76

exposure, respirator usage, and the employer’s exposure 

assessment data.

d. Cite 29 CFR § 1910.1053(i)(2) or 29 CFR § 1926.1153(h)(2) if the 

employer did not ensure the appropriate procedures and tests were 

provided as part of the employee’s initial examination.

e. Cite 29 CFR § 1910.1053(i)(3) or 29 CFR § 1926.1153(h)(3) if the 

employer did not make periodic examinations available at least 

every three years, or more frequently, if recommended by a 

PLHCP.

f. Cite 29 CFR § 1910.1053(i)(3) or 29 CFR § 1926.1153(h)(3) if the 

employer did not ensure the appropriate procedures and tests were 

provided as part of the employee’s periodic examination.

g. Cite 29 CFR § 1910.1053(i)(4) or 29 CFR § 1926.1153(h)(4) if the 

employer did not provide the required information to the 

examining PLHCP. Cite the appropriate subparagraph for the 

element(s) not provided (e.g., 29 CFR §§ 1910.1053(i)(4)(i)-(iv) or 

1926.1153(h)(4)(i)-(iv)).

h. Cite 29 CFR § 1910.1053(i)(5) or 29 CFR § 1926.1153(h)(5) if the 

written report was not provided to the employee.

i. If there was no written opinion provided to the employer, cite 29 

CFR § 1910.1053(i)(6)(i) or 29 CFR § 1926.1153(h)(6)(i). If the 

employer cannot produce a requested written opinion, see the 

recordkeeping citation guidance in Section IX.L below.

j. If employees were not given a written medical opinion within 30 

days of their examination, cite 29 CFR § 1910.1053(i)(6)(iii) or

29 CFR § 1926.1153(h)(6)(iii).

k. Cite 29 CFR § 1910.1053(i)(7) or 29 CFR § 1926.1153(h)(7) if the 

employer did not provide any required additional medical 

examination.

l. If any information is missing from the reports or opinions, CSHOs 

should cite the appropriate paragraphs.

K. Communication of Hazards.

1. General Information. 29 CFR § 1910.1053(j)(1) and 29 CFR § 

1926.1153(i)(1) require employers to include respirable crystalline silica 

in their hazard communication programs in accordance with 29 CFR §

1910.1200, and the program must address at least the following hazards: 
77

cancer, lung effects, immune system effects, and kidney effects. 

Communication of respirable crystalline silica hazards training is required 

for each employee covered by the standard (i.e., each employee who is, or 

could foreseeably be, exposed to respirable crystalline silica at or above 

the AL).

a. Hazard communication. The hazard communication requirements 

of the Silica standards complement existing requirements of 

OSHA's Hazard Communication standard (HCS), 29 CFR §

1910.1200, which covers employees exposed to respirable 

crystalline silica regardless of the airborne exposure level.

Therefore, the pre-existing duty under the HCS to provide 

education and training on health hazards associated with silica 

remains applicable for employees having workplace exposure to 

silica even at levels below the AL.

Employers must ensure that each employee has access to labels on 

silica containers and safety data sheets (SDS), and is trained in 

accordance with the provisions of HCS and 29 CFR § 

1910.1053(j)(3) or 29 CFR § 1926.1153(i)(2).

Note 1: For more information on the training requirements of the HCS, 

see CPL 02-02-079, Inspection Procedures for the Hazard 

Communication Standard, Section X.H., Employee Information and 

Training, July 9. 2015.

Note 2: Under the HCS, employers must maintain SDSs for each 

hazardous chemical they receive. Where the employer is not able to 

obtain an SDS for silica-containing materials that are being worked upon 

by the employees, the employer may use a representative SDS for hazard 

communication purposes.

b. Signs. 29 CFR § 1910.1053(j)(2) requires employers to post 

warning signs at all entrances to regulated areas. (See Section 

IX.F.1 (d) above).

Note: The construction silica standard has no requirement for regulated 

areas. However, there is a requirement for the employer’s ECP to describe 

procedures used to restrict access to work areas when necessary to 

minimize the number of employees exposed to silica and the level of 

employee exposure, including exposures generated by other employers. 

For more information, see Section IX.F.1-3 of this Instruction regarding 

29 CFR § 1926.1153(g)(1)(iv). Even though regulated areas with warning 

signs are not required for the construction standard, the employer may 

choose to include procedures for posting warning signs in its written ECP 

as a method to restrict access to work areas under 29 CFR §
78

1926.1153(g)(1)(iv).

c. Employee information and training. The silica standards 29 CFR §

1910.1053(j)(3)(i) and 29 CFR § 1926.1153(i)(2)(i) require 

employers to ensure that each employee who is covered by the 

silica standard can demonstrate knowledge and understanding of:

• The health hazards associated with exposure to silica;

• The specific tasks in the workplace that could result in exposure to 

silica;

• The specific measures the employer has implemented to protect 

employees from exposure to silica (e.g., engineering controls, work 

practices, and respiratory protection);

• The contents of the standard; and,

• The purpose and a description of the medical surveillance program. 

d. The construction standard (29 CFR § 1926.1153(i)(2)(i)(E)) also

requires employers to ensure that covered employees can 

demonstrate knowledge and understanding of the identity of the 

designated competent person.

e. The requirement for training is performance-oriented in order to 

allow flexibility for employers to provide training as needed to 

ensure that each employee can demonstrate the knowledge and 

understanding required under the rule:

• Employers can determine whether employees have the requisite 

knowledge through a variety of methods, such as discussion of the 

required training subjects, written tests, or oral quizzes (see 81 FR 

at 16845) and (GI FAQs # 55 and #56); and,

• The silica standards do not set a fixed schedule for periodic 

training, however additional or repeated training may be necessary. 

For example, if an employer observes an employee engaging in 

activities that contradict the employer’s training, it is a sign that the 

employee may require a reminder or periodic retraining on work 

practices (see 81 FR at 16850).

f. 29 CFR § 1910.1053(j)(3)(ii) and 29 CFR § 1926.1153(i)(2)(ii)

require employers to make a copy of the standard readily available
79

at no cost to each covered employee.

• Employees’ familiarity with and access to the requirements of the 

relevant respirable crystalline silica standard and their awareness 

of the employer’s obligations to comply with those requirements 

will allow them to more effectively participate in their own 

protection.

g. Acceptable forms of employee training may include hands-on 

training, videos, slide presentations, classroom instruction, 

informal discussions during safety meetings, written materials, or 

any combination of these methods (see GI FAQ #55).

h. To ensure that employees comprehend the material presented 

during training, it is critical that trainees have the opportunity to 

ask questions and receive answers if they do not fully understand 

the material presented to them (see GI FAQ #55). 

2. Inspection Guidelines. 

a. Review the employer’s written hazard communication program to 

determine whether it includes information and training on 

respirable crystalline silica hazards and associated control 

measures.

b. Determine whether an employee can demonstrate knowledge and 

understanding of silica-related hazards when interviewing 

employees. The CSHO should gather evidence from employees 

such as:

• When they were trained;

• How the training was conducted;

• Whether they were able to ask questions and receive answers;

• Whether the training was conducted in a language and manner they 

could understand;

• Whether they were paid for the time it took to complete the 

training;

• Whether employees know that respirable crystalline silica is 

hazardous and where and how exposure could occur;

• What engineering controls/work practices are used to control 
80

respirable crystalline silica exposures and if the employees can

demonstrate how to operate/maintain controls on the equipment 

they use (if applicable);

• Whether they understand the medical surveillance program; 

• Whether a copy of the applicable silica standard(s) is available to 

them; and,

• For employees in the construction industry, whether they know the 

identity of the designated competent person.

Note: An employer has the option of providing access to the silica 

standard(s) by means of a printed or electronic copy in a central location

or company website. However, when access is provided electronically, 

the employee must receive training on accessing designated computers 

that must be available at all times without any barriers to access. The 

employer should also have a back-up copy of the silica standard(s) should 

the website not be available.

3. Citation Guidelines. 

a. If respirable crystalline silica hazards were not communicated by 

general industry/maritime employers to their employees in 

accordance with 29 CFR § 1910.1053(j) or 29 CFR § 

1926.1153(i), then cite the appropriate subparagraph(s).

• If citing 29 CFR § 1910.1200(h)(2)(ii) and 29 CFR § 

1910.1200(h)(3)(ii)-(iii), consider grouping with appropriate 

subparagraphs of 29 CFR § 1910.1053(j)(1) and 1910.1053(j)(3) or

subparagraphs of 29 CFR § 1926.1153(i)(1) and 1926.1153(i)(2).

b. If the required hazard warning signs were not posted at all 

entrances to the regulated area(s) by general industry/maritime 

employers, then cite grouped violations of 29 CFR §

1910.1053(j)(2) and 1910.1053(e)(2)(ii).

c. When covered employees received inadequate respirable 

crystalline silica information or training (e.g., when the covered 

employees cannot demonstrate knowledge and understanding of 

required information), cite 29 CFR § 1910.1053(j)(3)(i) or 29 CFR 

§ 1926.1153(i)(2)(i), as appropriate. 

d. If the employer did not make a copy of the relevant silica standard 

readily available to affected employees without cost, cite
81

29 CFR § 1910.1053(j)(3)(ii) or 29 CFR § 1926.1153(i)(2)(ii), as

appropriate.

L. Recordkeeping.

1. General. 29 CFR § 1910.1053(k) and 29 CFR § 1926.1153(j) require 

employers to make and maintain accurate records of air monitoring data, 

objective data, and medical surveillance. Employers must both create and 

preserve such records. 

a. 29 CFR §§ 1910.1053(k)(1)(iii), (k)(2)(iii), and (k)(3)(iii) and

1926.1153(j)(1)(iii), (j)(2)(iii), and (j)(3)(iii) require employers to 

ensure that air monitoring data, objective data, and medical 

surveillance records are maintained and made available in 

accordance with 29 CFR § 1910.1020, Access to employee 

exposure and medical records. Therefore, employers must grant 

access to these records upon request by employees, their

designated representatives, or OSHA, as required by 

29 CFR § 1910.1020(e). 

b. The requirement to make and maintain air monitoring and 

objective data records only arises where the employer relies upon 

such data to comply with the requirements of the silica standards. 

See 29 CFR § 1910.1053(k)(2)(i) and 29 CFR § 1926.1153(j)(2)(i).

See below for a more detailed discussion.

c. OSHA standards no longer require that air monitoring data and 

medical surveillance records include the employee's social security 

number (SSN). An employer may still choose to use SSNs to 

identify employees but the numbers should be expunged from the 

records prior to allowing other parties access to the exposure 

records. An employer may develop an alternative method for 

identifying employees’ individual records.

Note: Recognizing the threat of identity theft and the availability of other 

methods for tracking employees for research purposes, OSHA published a 

rule that removed the requirements for employers to include employee 

social security numbers on exposure monitoring, medical surveillance, and 

other records from most OSHA health standards, including the Silica 

standards. See Standards Improvement Project--Phase IV, 84 FR 21451 

(May 14, 2019).

d. 29 CFR § 1910.1020 generally requires that employee exposure 

records be preserved for at least 30 years, and that an employee’s 

medical records be kept for the duration of the employee’s 
82

employment plus an additional 30 years. 

e. Medical Record retention exceptions: There are special rules that 

may apply to the retention of employee medical records under 

certain circumstances: 

• The medical records of employees who have worked for the 

employer for less than one year need not be retained beyond the 

term of employment if they are provided to the employee upon the 

termination of employment (see 29 CFR § 1910.1020(d)(1)(i)(C));

• Employers are responsible for maintaining medical records in their 

possession and in the PLHCP or specialist’s possession (e.g., the 

written medical report for the employee described in 29 CFR §

1910.1053(i)(5) and 29 CFR § 1926.1153(h)(5) (see GI FAQ #58

CON FAQ #53)).

• For records that are in the possession of the PLHCP or the 

specialist, employers can fulfill their obligations for record 

retention by including the retention requirement in the written 

agreement between the employer and the PLHCP or the specialist 

or by otherwise specifically communicating to the PLHCP or the 

specialist the substance of OSHA’s record-retention requirements 

(see GI FAQ #58, CON FAQ #53, and 81 FR at 16854).

• If an examination meeting the requirements of the silica standards

was offered to the employee by a previous employer and a new 

employer accepts a written medical report or opinion as proof of 

the examination, the new employer is NOT responsible for record 

retention by the PLHCP who conducted the examination for the 

previous employer. However, the new employer must maintain the 

written report or opinion he/she accepted from the employee.

f. In accordance with 29 CFR § 1910.1020(h)(1), employers ceasing 

to do business must transfer all employee exposure and medical 

records to the successor employer, whenever applicable. If there is 

no successor, then the employer who is ceasing to do business 

must notify affected current employees of their rights to access the 

records at least three months prior to the cessation. The employer 

should also make a good faith attempt to locate previous 

employees to provide them their records prior to disposal.

2. Specific requirements. 

a. 29 CFR § 1910.1053(k)(1) and 29 CFR § 1926.1153(j)(1) require 

employers who perform air monitoring to assess employee 
83

exposures to make and maintain accurate records of such 

monitoring that identify the monitored employee(s) and all 

employees whose exposures are represented by the monitoring. 

The employer is required to keep records for each exposure 

measurement taken. Specifically, 29 CFR § 1910.1053(k)(1)(ii) 

and 29 CFR § 1926.1153(j)(1)(ii) require the records to include the 

following information:

• The date of measurement for each sample taken;

• The task involving exposure to respirable crystalline silica that was 

monitored;

• Sampling and analytical methods used;

• The number, duration, and results of samples taken;

• Identity of the laboratory that performed the analysis; 

• The type of PPE used by the employees monitored; and,

• The name and job classification of all employees represented by 

the monitoring, indicating which employees were actually 

monitored (see GI FAQ #23).

b. Sections 1910.1053(k)(2) and 1926.1153(j)(2) require employers 

who use objective data to characterize employee exposures to 

make and maintain accurate records of this data. Specifically, 29 

CFR § 1910.1053(k)(2)(ii) and 29 CFR § 1926.1153(j)(2)(ii) 

require the records to include the following specific information: 

• The crystalline silica-containing material in question;

• The source of the objective data;

• The testing protocol and results of testing; 

• A description of the process, task, or activity involved; and

• Other data relevant to the process, task, activity, material, or 

employee exposures on which the objective data were based.

c. 29 CFR § 1910.1053(k)(3) and 29 CFR § 1926.1153(j)(3) require 

employers to establish and maintain an accurate medical 

surveillance record for each employee subject to the medical 

surveillance requirements. Specifically, 29 CFR §
84

1910.1053(k)(3)(ii) and 29 CFR § 1926.1153(j)(3)(ii) require the 

records to include the following specific information: 

• The employee’s name;

• A copy of the PLHCPs’ and specialists’ written medical opinions;

and,

• A copy of the information provided to the PLHCPs and specialists. 

Note: Employers have the flexibility to develop a system to uniquely 

identify employees who were monitored or included in medical 

surveillance.

3. Inspection Guidelines. 

a. The CSHO should review the employer’s recordkeeping including 

the employer’s air monitoring and objective data records.

• If the employer has taken air monitoring samples to assess 

employee exposure, the CSHO should review the employer’s air 

monitoring data to determine whether the employer is keeping an 

accurate record of all measurements taken as set forth in 29 CFR §

1910.1053(k)(1) and 29 CFR § 1926.1153(j)(1). If the employer is 

relying on objective data to assess employee exposure, the CSHO 

should review the objective data records for compliance with 29 

CFR § 1910.1053(k)(2) and 29 CFR § 1926.1153(j)(2). Where an 

employer’s objective data includes air monitoring data taken by the 

employer to assess employee exposure, the CSHO should ensure 

that the employer’s records comply with both 29 CFR §

1910.1053(k)(1) and paragraph (k)(2) or 29 CFR § 1926.1153(j)(1) 

and paragraph (j)(2). In general industry, the CSHO should also 

review an employer’s objective data relied on to demonstrate that 

the silica standard does not apply per 29 CFR § 1910.1053(a)(2);

b. The CSHO should also review the employer’s medical surveillance 

records for employees exposed to respirable crystalline silica. 

Whenever reviewing medical opinions, the CSHO should follow

OSHA Instruction CPL 02-02-072, Rules of Agency Practices and 

Procedure Concerning OSHA Access to Employee Medical 

Records, Aug. 22, 2007.

c. Retention: The records should be examined to determine whether

the employer is keeping employee exposure records for 30 years

and employee medical records for the duration of employment plus 

30 years. See Section IX.L.1.e regarding rules for retention of 
85

medical records under special circumstances.

4. Citation Guidelines. 

a. If the employer is relying on air monitoring data, but has not 

maintained the air monitoring data records or the records are 

missing certain required elements:

• Cite 29 CFR § 1910.1053(k)(1)(i) or 29 CFR § 1926.1153(j)(1)(i)

for not maintaining the air monitoring records; and

• Cite 29 CFR § 1910.1053(k)(1)(ii) or 29 CFR § 1926.1153(j)(1)(ii) 

if the air monitoring records are missing certain elements.

b. If the employer is relying on objective data but has not maintained 

records of the objective data:

• For general industry/maritime, cite 29 CFR § 1910.1053(k)(2)(i);

• For construction, cite 29 CFR § 1926.1153(j)(2)(i).

c. If the employer’s objective data records are missing certain 

required elements:

• For general industry/maritime, cite 29 CFR § 1910.1053(k)(2)(ii);

• For construction, cite 29 CFR § 1926.1153(j)(2)(ii).

d. If the employer has not made or maintained required medical 

surveillance records:

• For general industry/maritime, cite 29 CFR § 1910.1053(k)(3)(i);

• For construction, cite 29 CFR § 1926.1153(j)(3)(i). 

e. If the records are missing certain required elements (e.g., 

physician’s written opinion):

• For general industry/maritime, cite 29 CFR § 1910.1053(k)(3)(ii);

• For construction, cite 29 CFR § 1926.1153(j)(3)(ii).

f. If the employer is not maintaining records of air monitoring data, 

objective data, or medical surveillance records in accordance with 

29 CFR § 1910.1020 (for example, if employees’ air monitoring 

records were not being maintained):
86

• For general industry/maritime, cite 29 CFR § 1910.1053(k)(1)(iii), 

(k)(2)(iii), or (k)(3)(iii) and group with the appropriate provision of

29 CFR § 1910.1020(d)(1)(i) or 1910.1020(d)(1)(ii);

• For construction, cite 29 CFR § 1926.1153(j)(1)(iii), (j)(2)(iii), or 

(j)(3)(iii), and then group with the appropriate provision of 

29 CFR § 1910.1020(d)(1)(i) or 1910.1020(d)(1)(ii).

Note: All appropriate subparagraphs should be cited if the records are 

missing more than one of the required elements.

M. Dates.

1. 29 CFR § 1910.1053(l) and 29 CFR § 1926.1153(k) establish effective 

and compliance dates.

a. The Respirable Crystalline Silica standards became effective June 

23, 2016.

b. The compliance dates for the general industry/maritime standard 

are as follows:

• Except as outlined below, employers must comply with all the 

requirements of the general industry/maritime standards by June 

23, 2018;

• The requirement to make medical surveillance available to 

employees who are occupationally exposed to respirable 

crystalline silica at or above the action level for 30 days or more 

per year, per 29 CFR § 1910.1053(i)(1)(i), became enforceable

June 23, 2020;

• The obligation to make medical surveillance available to 

employees who are occupationally exposed to respirable 

crystalline silica above the PEL for 30 days or more per year, per 

29 CFR § 1910.1053(i)(1)(i), was enforceable from June 23, 2018

to June 22, 2020.

c. For hydraulic fracturing operations in the oil and gas industry, the 

engineering and work practice control requirements in 29 CFR

§ 1910.1053(f)(1) become enforceable on June 23, 2021. See

Appendix G for hydraulic fracturing inspection guidelines.

d. The compliance dates for construction standards are as follows:
87

• OSHA began enforcing the construction standard on September 

23, 2017 (i.e., subject to an extension from the original compliance 

date, which was June 23, 2017);

• The requirements for methods of sample analysis (in 

29 CFR § 1926.1153(d)(2)(v)) commenced on June 23, 2018. 

X. Multi-Employer. 

A. Overview.

1. In a situation where workers from different employers are simultaneously 

exposed to respirable crystalline silica hazards, enforcement may be 

subject to the OSHA multi-employer citation policy. These scenarios are 

most likely to occur on construction sites. See OSHA Instruction CPL 02-

00-124, Multi-Employer Citation Policy, December 10, 1999. The 

directive’s guidance and citation policies provide information on the need 

for employers to communicate and protect against hazardous conditions 

workers may be exposed to when working with respirable crystalline 

silica.

2. At multi-employer worksites (in all industry sectors), more than one 

employer may be citable for a hazardous condition that violates an OSHA 

standard. A two-step process is followed in determining whether more 

than one employer is to be cited: 

a. Step 1: Determine whether the employer is a creating, exposing, 

correcting, or controlling employer. See Sections X.B, X.C, X.D,

and X.E of OSHA's Multi-Employer Citation Policy for more

information about and examples of each of these types of 

employers. If the employer falls into one of these categories, it has 

obligations under the silica standards. 

b. Step 2: Determine if the employer's actions were sufficient to meet 

those obligations. The extent of the actions required of employers 

varies based on which category applies. 

3. Communication of hazards to other employers is part of an employers’ 

duties under its written hazard communication program. This includes, 

among other things, the methods the employer will use to inform others of 

any precautionary measures to protect employees. See 29 CFR § 

1910.1200(e)(2)(ii).

4. CSHOs should carefully evaluate scenarios where a single silica-related 

task exposes employees of multiple employers. Ensure that employees are 
88

protected, including that they are provided with and wear the appropriate 

PPE.

Note: Employers covered by the construction standard must establish and 

implement procedures to restrict access to work areas, where necessary

(e.g., when respirator use is required), to minimize the number of 

employees exposed to respirable crystalline silica and their level of 

exposure, including exposures generated by other employers or sole 

proprietors. See 29 CFR § 1926.1153(g)(1)(iv). 

B. Inspection Guidelines. 

1. Inspection procedures outlined in this Instruction may apply to multiemployer work sites. During opening conferences on all silica-related 

construction inspections, CSHOs should:

a. Determine the names of all contractors involved in tasks 

potentially generating respirable crystalline silica and whose

employees are engaged in such tasks.

b. Review relevant documentation including, but not limited to, the 

minutes from any safety meeting where respirable crystalline silica 

exposures were discussed; as well as the ECP and a copy of the 

written hazard communication program.

c. Determine through interviews and observations whether other 

contractors are exposed to respirable crystalline silica. If so, 

proceed as instructed in the applicable sections of this Instruction. 

C. Citation Guidelines.

a. All the citation guidelines mentioned in this Instruction apply to

multi-employer citations (i.e., when applicable several employers 

can be cited for the same violation). 

• Example 1: Two workers engaged in a sandblasting activity are 

exposed to silica exposure levels above the PEL. While doing the 

walkaround, the CSHO also observed carpenters working in the 

area exposed to the silica hazards. If the conditions violate the 

silica standard, both employers may be cited. For example, the

sandblasting contractor for creating the hazard and exposing its 

workers, and the carpenters’ employer for exposing their workers 

to the silica hazard.

• Example 2: The CSHO observed carpenters (on-site contractors) 

working in areas generating silica at a general industry site and the 
89

host employer’s employees were also being subjected to silica 

exposures; both employers may be cited for failing to protect their 

workers.

XI. Temporary Workers. (See GI FAQs #59 to #64).

A. Overview.

1. Host employers that use staffing agencies that supply temporary workers 

have obligations to ensure compliance with the Silica standards, as both 

the host and the staffing agency are considered joint employers of those 

workers. 

2. Temporary workers are entitled to the same protections as other 

employees under the Occupational Safety and Health Act and OSHA 

health and safety standards. Therefore, temporary workers within the 

scope of the Silica standards must be protected as required by the 

standard. The duration of their employment is irrelevant.

3. Staffing agencies and host employers are responsible for determining the 

conditions of employment and for complying with the Silica standards. 

Both share control over temporary employees, and are therefore 

responsible for ensuring that these employees are effectively informed and 

trained on workplace hazards.

4. Some worksite-specific training is always required, and host employers 

are generally better situated to provide training on worksite-specific job 

tasks, machinery, equipment, processes, and measures taken to protect 

workers.

5. The staffing agency and the host employer must communicate and 

coordinate to ensure that the temporary workers are fully protected under 

the standard. While the host employer is often better situated to assess

hazards and protect temporary workers from silica-related hazards in the 

workplace, the staffing agency may be better positioned to offer other 

protections under the silica standard, such as general training and medical 

surveillance.

6. Host employers must ensure that the exposures of temporary workers are 

assessed when required by 29 CFR § 1910.1053(d)(1) or 29 CFR § 

1926.1153(d)(2) and ensure that they are not exposed to silica above the 

PEL. 

7. A general industry host employer has no obligation to make medical 

surveillance available to temporary workers who will not be 

occupationally exposed to silica at or above the applicable threshold for 30 
90

or more days per year while working for the host employer. If the 

temporary worker will be exposed above the threshold for 30 days or more 

at the host site, and the worker has not had a medical examination that 

meets the requirements of the standard within the last three years, the host 

employer and staffing agency must ensure that medical surveillance is 

available. See 29 CFR § 1910.1053(i)(1)(i) and paragraph (i)(3).

8. In construction, if the temporary worker will be required to wear a 

respirator while working for the host employer for 30 or more days per 

year, and the worker has not had a medical examination that meets the 

requirements of the standard within the last three years, the construction 

host employer and staffing agency must ensure that medical surveillance is 

available. See 29 CFR § 1926.1153(h)(1)(i) and (h)(3).

9. The staffing agency must determine the total days per year of exposure 

above the threshold (in general industry) or the total days per year of 

respirator use (in construction) during all periods of employment with all 

host employers and must add those days together to determine whether 

medical surveillance must be made available to a temporary worker.

Note: Employers decide whether a division of compliance responsibilities

may be appropriate. In doing so, the staffing agency and host employer 

should jointly review the task assignments and potential workplace

hazards. The details of the training and protective measures to be 

provided may be set forth contractually. However, neither employer may 

avoid its duties under the OSH Act by shifting responsibilities to the other 

employer.

B. Inspection Guidelines.

1. During all silica-related inspections, CSHOs should determine whether 

there are temporary employees that are exposed to respirable crystalline 

silica.

Note: CSHOs should request and review relevant documentation such as 

any agreements between the host employer and the temporary agency to 

help determine their responsibilities. 

2. If any temporary workers are exposed to silica-related hazards, follow the 

guidance in the applicable sections of this directive.

3. CSHOs should gather evidence and determine whether the host employer

has provided the following:

a. Host employers must ensure that the exposures of temporary 

workers who are or may reasonably be expected to be exposed to 
91

silica at or above the AL are assessed using either the general 

industry/maritime performance option in 29 CFR § 

1910.1053(d)(2) or the scheduled monitoring option in 29 CFR § 

1910.1053(d)(3), or the construction options in 29 CFR § 

1926.1153(d)(2)(ii) or paragraph (d)(2)(iii), where applicable. 

b. Host employers using the performance option may rely on the 

same objective and/or air monitoring data used to assess the 

exposures of permanent employees, as long as such data accurately 

characterize the exposures of the temporary workers. See 29 CFR 

§ 1910.1053(d)(2) or 29 CFR § 1926.1153(d)(2)(ii).

c. Host employers using the scheduled monitoring option may rely 

upon representative sampling to assess the exposures of temporary 

workers if they are performing the same tasks on the same shift 

and in the same work area as the employees whose exposures have 

been sampled. (Representative sampling involves sampling the 

employees expected to have the highest silica exposures.) See

29 CFR § 1910.1053(d)(3)(i) or 29 CFR § 1926.1153(d)(2)(iii)(A).

d. Host employers must ensure that temporary workers are not 

exposed to silica above the PEL, using the hierarchy of controls set 

forth in the standard. Where respiratory protection is required, the 

host employer and the staffing agency should reach agreement as 

to which employer will provide and pay for the respirators. 

Note: Although the host employer is often better situated to assess and 

control workplace hazards than the staffing agency, both parties may agree 

to have the staffing agency provide respirators, as well as medical 

evaluations and fit testing required for respirator use, in accordance with 

section 1910.134. 

e. OSHA recommends that staffing agencies and host employers 

coordinate responsibilities for the various aspects of silica-related 

training and inform each other when they have fulfilled their 

respective training obligations. See:

https://www.osha.gov/temp_workers/index.html and

https://www.osha.gov/Publications/OSHA3859.pdf.

f. Staffing agencies and host employers should also review OSHA’s 

Temporary Worker Initiative (TWI) Bulletin No. 5 - Hazard 

Communication, for further guidance: 

https://www.osha.gov/Publications/OSHA3860.pdf

C. Citation Guidelines.

1. The citation guidelines in this directive apply to the host employer, the 
92

staffing agency, or both, depending on the employment agreement and 

case-specific circumstances. Where applicable, both entities may be cited 

for the same violation.

• The CSHO should cite the staffing agency and the host employer under 

29 CFR § 1910.1053(j) or 29 CFR § 1926.1153(i) if no effort was made 

to determine what kind of work tasks/operations the workers would be 

performing at the host site.

• The CSHO should cite the host employer under 29 CFR § 1910.1053(j) 

or 29 CFR § 1926.1153(i) if it did not provide the necessary site-specific 

training. 

2. Issuance of citations to staffing agencies are to be evaluated on a case-bycase basis.

XII. Drafting OSHA Citations for Silica Violations. 

A. The compliance officer should follow the general procedures for writing OSHA 

citations in the FOM, CPL 02-00-164, and any specific procedures in this 

Respirable Crystalline Silica Directive. The recommended classification of 

violations shall be as per the FOM, Violations, Chapter 4, or as per subsequent 

revisions. Violations of the Silica standards will generally be classified as 

“serious” given the potential for severe impairment of health.

OSHA has developed Standard Alleged Violation Elements (SAVEs) specific to 

the Silica standards for use by compliance officers to ensure consistent writing 

of citations. If there is no SAVE that covers the alleged violation, the 

compliance officer shall develop the alleged violation description using existing 

procedures. (See OSHA Instruction CPL 02-00-035, Changes to Regulatory 

and General Industry Standard Alleged Violation Elements (SAVEs) Manual.)

The general procedures for classifying and grouping violations in the FOM

should be followed. This Instruction also contains some specific instructions 

for grouping violations of multiple provisions within the Silica standards and 

for grouping violations of one or more provisions of a Silica standard and other 

OSHA standards. Deviations that appear appropriate, however, may be 

addressed with the Regional Office.

XIII. Training for OSHA Personnel.

A. For all inspections or on-site visits where silica exposures are expected, CSHOs 

and OSHA consultation staff are expected to be knowledgeable of:

1. Potential hazards which may be encountered at the site, including the 

potential hazards of silica. 
93

2. Contents of the Silica standards and this Instruction. 

3. Appropriate PPE to be worn. Each CSHO/OSHA consultation staff who 

will be expected to use PPE shall be trained in the proper care, use, and 

limitations of the PPE. Use of respiratory protection by CSHOs and other 

Agency personnel is addressed in OSHA Instruction CPL 02-02-054, 

Respiratory Protection Program Guidelines, July 14, 2000.

XIV. Medical Examinations for OSHA Personnel. 

A. Many of the hazards CSHOs may encounter are specifically addressed by the 

medical surveillance requirements in OSHA standards. In accordance with 

OSHA personnel policy in OSHA Instruction PER 04-00-005, OSHA Medical 

Examination Program, Aug. 22, 2009, Regional Administrators and Area 

Directors (AD) are responsible for implementing a medical examination program 

for CSHOs.

B. OSHA Instruction CPL 02-02-054, Respiratory Protection Program Guidelines,

July 14, 2000, includes medical evaluation requirements for OSHA personnel 

required to wear respiratory protection. The instruction requires that CSHOs be 

medically evaluated and found eligible to wear the respirator selected for their use 

prior to fit testing and first-time use of the respirator in the workplace. CSHOs

who are required to wear any respiratory protection shall be medically cleared via 

the CSHO Medical Examination procedures.

XV. Protection of OSHA Personnel.

A. CSHOs must use appropriate PPE when they are exposed to a hazard. CSHOs 

shall not enter a respirable crystalline silica-regulated area, or other area where 

exposures are likely to exceed the PEL, unless it is absolutely necessary. If 

necessary, CSHOs should first discuss the need with their AD or Assistant Area 

Director prior to entering. For inspection and air sampling activities, remote 

operations are encouraged when practical.

B. Personal Protective Equipment (PPE).

1. Regional Administrators and ADs shall ensure that appropriate PPE is 

available for CSHOs.

2. CSHOs shall wear appropriate respiratory protection in the unlikely event 

of entering a respirable crystalline silica-regulated area or other area where 

exposures are likely to exceed the AL.

3. In some instances, a CSHO may find that an employer’s exposure 

assessment is inadequate, has not been performed at all, the employer has 

not fully and properly implemented Table 1 controls, or exposures may 
94

exceed the PEL. In such cases, use professional judgment in anticipating 

exposure during a brief entry into a silica-related work area for inspection. 

CSHOs shall comply with the Regional or Area Office’s respiratory 

protection program.

4. Respirators shall be selected in accordance with the respirator selection 

procedures in CPL 02-02-054, Respiratory Protection Program 

Guidelines, July 14, 2000. Respirators shall also meet OSHA’s APFs, as 

set forth in 29 CFR § 1910.134. 

5. CSHOs should refer to the Safety and Health Management System (SHMS) 

for OSHA employees, Chapter 27, Exposure Monitoring, for further guidance 

on PPE and employee exposure sampling:

https://www.osha.gov/enforcement/directives/adm-04-00-003

XVI. OSHA Information System (OIS) Coding Instructions.

A. All OSHA inspections (i.e., complaints, referrals, NEP) involving respirable 

crystalline silica shall be coded “RCS-NEP.” All previous IMIS/OIS codes 

including “N-02-Silica” shall not be used.

B. Refer to the appropriate inspection classification fields in the OIS Enforcement 

User Guide for further guidance.
A-1

Appendix A

Flow Charts for Evaluating Construction Employer Methods of Controlling Exposure 

to Respirable Crystalline Silica

Flowchart A: Specified Exposure Controls for Table 1 Tasks

In general, if employees are performing Table 1 tasks, and the employer has not implemented 

controls, and has not conducted an exposure assessment, then the employer is in violation of

paragraphs (c) and (d). For each employee with occupational exposure to respirable 

crystalline silica (RCS), CSHOs should consider the following questions.

1. Is any employee performing a task listed in Table 1? 

If Yes, go to Q2.

If No, evaluate compliance with 29 CFR § 1926.1153(d) – see Flowchart B.

2. Are the engineering controls and work practices listed for that Table 1 task in use?

If Yes, go to Q3.

If No, evaluate compliance with 29 CFR § 1926.1153(d) – see Flowchart B.

3. Are the engineering controls fully and properly implemented? 

If Yes, go to Q4.

If No, evaluate compliance with 29 CFR § 1926.1153(d) – see Flowchart B.

4. Is the employee wearing the required level of respiratory protection? 

If Yes, employer is in compliance with Table 1.

If No, evaluate compliance with 29 CFR § 1926.1153(d) – see Flowchart B.

Note 1: CSHOs should repeat Flowchart A for each employee engaged in a Table 1 task. 

Note 2: To determine whether the engineering controls, work practices, and respiratory 

protection specified in Table 1 are fully and properly implemented, CSHOs should consult 29 

CFR § 1926.1153(c)(2), which contains additional requirements for tasks performed indoors 

or in an enclosed area, and for control measures involving wet methods or an enclosed cab or 

booth. CSHOs should also consult equipment manufacturer’s instructions to ensure the 

equipment is operated and maintained in accordance with manufacturer’s instructions to 

minimize dust emissions.

Note 3: In determining the respiratory protection required by Table 1, CSHOs should note 

that Table 1 may specify different respirator requirements for tasks performed < 4 hours/shift 

and > 4 hours/shift. 29 CFR § 1926.1153(c)(3) contains additional instructions regarding 

how task duration should be calculated for the purposes of respirator usage where an 

employee performs more than one task on Table 1 during the course of a shift.
A-2

Flowchart A: Specified Exposure Controls for Table 1 Tasks
A-3

Flowchart B: Alternative Exposure Control Methods

1. Are workers performing tasks with foreseeable exposure to RCS at or above the 

action level? (Note that the use of engineering controls to maintain exposure below

the AL indicates that the standard covers the operation.)

If Yes, go to Q2.

If No, the standard does not apply to exposures that will remain below the AL 

under any foreseeable conditions.

2. Has the employer conducted an exposure assessment for each employee who is or 

may reasonably be expected to be exposed at or above the AL?

If Yes, go to Q3.

If No, the employer is not in compliance with paragraph (d)(2)(i). Conduct 

exposure monitoring as necessary to assess compliance with PEL and go to Q5. 

3. Is the exposure assessment representative of current conditions?

If Yes, the employer is in compliance with (d)(2)(i); go to Q4.

If No, the employer is not in compliance with paragraph (d)(2)(i). Conduct 

exposure monitoring as necessary to assess compliance with PEL and go to Q5.

4. Does the employer’s exposure assessment show that employees are exposed at or 

below the PEL?

If Yes, the CSHO need not conduct exposure monitoring and the employer is in 

compliance with paragraph (d).

If No, the CSHO should conduct exposure monitoring, and go to Q5.

5. Does CSHO exposure monitoring show employee exposure at or below the PEL?

If Yes, the employer is in compliance with paragraph (d)(1).

If No, go to Q6.

6. Has the employer implemented all feasible engineering and work practice controls to 

reduce RCS exposure to or below the PEL?

If Yes, go to Q7.

If No, the employer is not in compliance with paragraphs (d)(1) and (d)(3)(i). 

7. If respiratory protection is required, are workers wearing the required level of 

respiratory protection?

If Yes, the employer is in compliance with paragraphs (d)(1), (d)(3)(i), and (e).

If No, the employer is not in compliance with paragraphs (d)(1), (d)(3)(i), and 

(e).
A-4
B-1

Appendix B

Instructions for Air Samples

Air samples are collected by drawing workplace air through a pre-weighed 37-mm diameter 

low ash polyvinyl chloride (PVC) filter with a 5-μm pore size preceded by 10-mm nylon 

Dorr-Oliver cyclone, following the procedures described in OSHA Method ID-142.1 Each

PVC filter is housed in an assembly composed of an aluminum cowl and a stainless steel 

support ring. The assembly is encapsulated in a plastic cassette. 

Pump Calibration: 

When operated at the experimentally determined sampling rate of 1.7 l/min, Dorr-Oliver 

cyclones are capable of sampling only particulates that are in the respirable size range. 

Therefore, calibration of the air flow rate is of critical importance when using cyclones to 

sample respirable particulate. The personal sampling pump must be calibrated with a 

representative filter in-line, following the procedure described in the OSHA Technical 

Manual.2 The required air flow rate is 1.7 L/min. Samples collected using other sampling 

rates are considered non-respirable because the particle-size fractions do not conform to the 

specified size definition.3

When calibrating the sampling pump, use a separate filter; do not use the actual filter 

intended for compliance sampling. 

Assemble the sampler as shown in 

Figure 1. Draw air directly into the 

inlet of the cyclone and through the 

filter cassette (inlet side down). The air 

should not pass through any hose or 

tubing before entering the cyclone.

During sampling, do not invert the 

sampler. Instruct the person being 

sampled not to invert the sampler. 

Inverting the cyclone can cause 

oversize material from the cyclone grit pot to spill onto the filter. Incorrect positioning of the 

sampling apparatus can interfere with sampling. The cyclone must be mounted vertically

 1 Stones, F., Robinson, E., Johansen, D., Albrecht, B. Crystalline Silica Quartz and Cristobalite (OSHA ID142), 2016. U.S. Department of Labor, Occupational Safety and Health Administration. 

https://www.osha.gov/dts/sltc/methods/inorganic/id142/id142_v4.html (accessed November 2019).

2 OSHA Technical Manual (OTM). United States Department of Labor, Occupational Safety and Health 

Administration. https://www.osha.gov/dts/osta/otm/otm_ii/otm_ii_1.html#appendix_II_6 (accessed November 

2019).

3 Ettinger, H. J., Partridge, J. E., Royer, G. W. Calibration of Two-Stage Air Samplers. Am. Ind. Hyg. Assoc. J,

1970, 31, 537-545.

Figure 1. Sampling filter cassette and Dorr-Oliver cyclone.
B-2

with the cyclone inlet facing outward. The grit pot must not become overloaded and the 

cyclone inlet must remain unobstructed. 

After sampling for the appropriate time, disconnect the sampler from the sampling pump and 

seal the filter cassette with end plugs. Seal the sampler with a Form OSHA-21. Submit at 

least one blank sample with each set of samples. Handle the blank sample in the same 

manner as the other samples, except draw no air through it.

Record sample air volume (L), sampling time (min), and sampling rate (L/min) for each 

sample, along with any potential interferences on the OSHA Sampling Sheet. Submit 

samples to the OSHA Salt Lake Technical Center (SLTC). Request analysis for silica, 

crystalline, mixed respirable (quartz, cristobalite, tridymite), IMIS code 9000. Cristobalite is 

a polymorph of respirable crystalline silica that occurs in workplaces where silica is heated to 

extremely hot temperatures (>1460 °C). If it is suspected that cristobalite may be present, 

note this on the OSHA Sampling Sheet. 

Bulk sampling is optional. In cases where bulk samples are submitted, any of the following 

are acceptable in decreasing order of preference: 

1) High-volume filter sample without cyclone (preferably >1.0 g). This is an air sample 

taken without a cyclone using a sampling rate greater than what is recommended. 

This results in the sampling of a larger air volume. It is submitted and identified for 

analysis as a bulk sample.

2) Representative settled dust (e.g., rafter sample). Submit 1-20 grams of bulk sample 

in a 20-ml glass scintillation vial sealed with a PTFE-lined cap.

3) Sample of the bulk material in the workplace. Submit 10-20 grams of bulk sample in 

a 20-ml glass scintillation vial sealed with a PTFE-lined cap. 

If bulk samples are taken, seal the sample with a Form OSHA-21. Identify the composition 

of the sample (if known) on an OSHA Sampling Sheet and identify the air samples that are 

associated with the bulk sample(s). The applicable IMIS code for bulk samples S103 (silica 

(quartz, total), or S105 (silica (cristobalite, total), must be used. Ship bulk samples 

separately from air samples. Bulk samples can be used to confirm the presence of 

crystalline silica at the worksite. Bulk samples cannot be used to determine exposure levels

to respirable crystalline silica. 

OSHA Sampling Sheet:

OSHA SLTC will analyze all silica samples submitted with IMIS code 9000 for quartz. 

Cristobalite is rare and will usually only be analyzed if the reason to suspect its presence is 

noted on the OSHA Sampling Sheet. Tridymite, which is even rarer, will not be analyzed by 

SLTC because a standard reference material is not readily available.
B-3

All sample results will be reported on Form OSHA 91B as μg/m3 and the severity calculation 

will use the PEL 50 μg/m3 for silica, crystalline, and mixed respirable quartz and cristobalite.

Samples collected without a cyclone or at a sampling rate other than 1.7 ± 0.2 L/min are 

considered non-respirable samples. These samples are analyzed and reported in the same 

manner as respirable samples; however, they are reported using IMIS codes S103 silica 

(quartz, total) or S105 silica (cristobalite, total). See link for OSHA sampling method 

information:

https://www.osha.gov/dts/sltc/methods/inorganic/id142/id142_v4.html.
B-4

Cyclone Leak Test Procedure

This section summarizes procedures for leak testing of the Dorr-Oliver cyclone samplers used for 

collecting respirable dust. Further details on this procedure are contained in the Cyclone Leak 

Test Procedure (CLTP), available through the OSHA Cincinnati Technical Center (CTC) 

(OSHA, 1997). www.osha.gov/dts/ctc/cycloneleaktestprocedure/cycleak.html. Compliance 

Safety and Health Officers (CSHOs) should review the entire leak test procedure before 

conducting the leak test as summarized below. The CLTP provides for more specific procedures 

for leak tests. 

Note: If using the Cyclone Leak Test and Pump Calibration Kit offered by the CTC, use the 

quick reference cards included in the kit in combination with the CLTP procedure.

Nylon Part Inspection:

• Disassemble the cyclone assembly, clean it, and inspect it for cracks and worn fit between parts. 

Take care not to scratch the inside surface of the cyclone chamber. 

• Replace any worn or cracked units or parts. 

O-Ring, Tubing, and Filter Leak Test:

• Connect the entire cyclone assembly (minus the cyclone body) to the pressure gauge and 

aspirator, maintaining the normal spacing between the plastic filter adaptor (coupler) and the 

vortex finder. 

• Seal the cyclone vortex finder opening by placing an airtight cap or your fingertip over the hole. 

• Hold the cyclone assembly together with one hand. 

• With your other hand, squeeze and gently release the aspirator bulb until the pressure gauge 

reads between 4" H2O and 10" H2O, then fold the tubing halfway between the “Tee” fitting and 

the aspirator. If the pressure reading is beyond full scale, release the vacuum and try again. 

• Observe the pressure gauge reading for 30 seconds. If the pressure drops less than 25 percent, 

the leakage is acceptable and the unit passes the leak test. If the pressure drops more than 25 

percent, corrective action is necessary. Sources of leaks include worn or damaged O-rings, 

cracked or ill-fitting tubing, and leaky pre-weighed filter cassettes. 

Note: Leaks between the filter input and the air sampling pump are more disruptive than leaks at 

the plastic filter adaptor O-rings. 

Final Pump-Fault Leak Test:

• Connect the cyclone assembly to the pump in the normal sampling configuration with the air 

sampling pump running at 1.7 L/min. 

• Close the inlet to the cyclone with tape or a finger. If the pump bears down and goes into a 

fault mode, the assembly passes this final, but crude, pump-fault leak test. 

Reference:

Occupational Safety and Health Administration (OSHA). Cyclone Leak Test Procedure. OSHA 

Cincinnati Technical Center. September 15, 1997. 
C-1

Appendix C

Sample Calculation of Time-Weighted Average (TWA) Exposures

Both the PEL and the AL are expressed as 8-hour TWA exposures. TWA measurements account 

for variable exposure levels over the course of a work shift by averaging periods of higher and 

lower exposures. The TWA exposure for an 8-hour work shift is calculated using a simple 

formula:

TWA = (Ca Ta + Cb Tb . . . Cn Tn) ÷ 8

Where: 

TWA is the time-weighted average exposure for the work shift

C is the concentration during any period of time (T) where the concentration remains constant; 

and T is the duration in hours of the exposure at the concentration (C).

For example, assume that an employee is exposed to respirable crystalline silica in an 8-hour 

workday as follows: 

Two hours exposure at 100 μg/m3

Two hours exposure at 50 μg/m3

Four hours exposure at 10 μg/m3

Enter this information in the formula:

(2 x 100 + 2 x 50 + 4 x 10) ÷ 8 = 42.5 μg/m3

Use the formula for Severity (SAE) and Upper/Lower Confidence Limits (UCL and LCL) in 

order to determine overexposure. (OSHA Technical Manual-Silica)
D-1

Appendix D 

Silica Background Information and Additional References

This appendix provides an overview of the following silica-related topics: the forms and sources 

of silica; common industrial uses of silica and workplaces with silica exposure; the history of 

silicosis; and health effects associated with exposure. The reference list at the end of this 

appendix provides many sources that may prove useful to those interested in a more in-depth 

treatment of these topics. 

Introduction:

“Silica” is a term that refers broadly to the mineral compound silicon dioxide (SiO2). It can exist 

in either crystalline or amorphous states, but amorphous silica is not covered under the new 

Silica standards. Thus, the term “silica” as used in this document typically refers to crystalline 

silica. 

Silica is a compound composed of the elements silicon and oxygen (chemical formula SiO2). 

Silica has a molecular weight of 60.08, and exists in crystalline and amorphous forms in the 

natural environment and during manufacturing or other processes. These substances are odorless 

solids, have no vapor pressure, and create non-explosive dusts when particles are suspended in 

air (U.S. EPA 1996).

Silica is classified as part of the “silicate” class of minerals, which includes compounds that are 

composed of silicon and oxygen and which may also be bonded to metal ions or their

oxides. When they bond with metal and metal oxides (commonly of iron, magnesium,

aluminum, sodium, potassium, and calcium), they form the silicate minerals commonly found in 

nature.

Forms and Sources of Crystalline Silica:

Crystalline silica occurs in three primary mineralogical forms, or polymorphs: quartz, 

cristobalite, and tridymite. Silica is also called “free silica,” to distinguish it from the silicates, 

which are minerals containing silicon dioxide bound to one or more cations [Beckett et al., 

1997]. Quartz is by far the most common form of naturally occurring silica [Davis, 1996; IARC, 

1997]. Cristobalite and tridymite, which are molecularly identical to quartz, are distinguishable 

by their unique crystalline structures. They are less stable than quartz, thus accounting for the 

dominance of the quartz form. Quartz itself exists as either of two sub-polymorphs: alpha-quartz 

(also known as low quartz), and beta-quartz (high quartz). Alpha-quartz is the 

thermodynamically stable form of crystalline silica and accounts for the overwhelming portion of 

naturally occurring crystalline silica [IARC, 1997]. 

Quartz is a major component of soils and is readily found in both sedimentary and igneous rocks, 

although the quartz content varies greatly from one rock type to another. For instance, granite 

contains on average about 30 percent quartz, and shales contain about 20 percent quartz. Natural 

stone, such as beach sand or sandstone, may be nearly pure quartz [IARC, 1997; Davis, 1996]. 
D-2

Cristobalite and tridymite are natural constituents of some volcanic rock, and man-made forms 

result from direct conversion of quartz or amorphous silica that has been subjected to high 

temperature or pressure. Diatomaceous earth, composed of amorphous silica, crystallizes during 

heating (calcining), yielding a calcined product that contains as much as 75 percent cristobalite. 

Cristobalite is also found in the superficial layers of refractory brick that has been repeatedly 

subjected to contact with molten metal [Markowitz and Rosner, 1995; Ganter, 1986; Cheng et 

al., 1992; Bergen et al., 1994]. 

Major Industrial Sources of Crystalline Silica Exposure:

Crystalline silica is an important industrial material, and occupational exposure occurs across a 

broad range of industries. There are over 30 major industries and operations where exposures to 

crystalline silica can occur. They include such diverse workplaces as foundries, dental 

laboratories, concrete products, and paint and coating manufacturing, as well as construction 

activities like masonry cutting, drilling, grinding and tuckpointing, and use of heavy equipment 

during demolition activities involving silica-containing materials. 

Sand and gravel are used in road building and concrete construction. Sand with greater than 

98% silica is used in the manufacture of glass and ceramics. Silica sand is used to form molds 

for metal castings in foundries, and in abrasive blasting operations. Silica is also used as a filler 

in plastics, rubber, and paint, and as an abrasive in soaps and scouring cleansers. Silica sand is 

used to filter impurities from municipal water and sewage treatment plants, and in hydraulic 

fracturing for oil and gas recovery (Document ID 1334, p. 111

). Silica is also used to 

manufacture artificial stone products used as bathroom and kitchen countertops, and the silica 

content in those products can exceed 85 percent (Document ID 2178, Attachment 5, p. 420).

The Final Rule’s economic analysis has a listing of general industry, maritime, and construction 

North American Industry Classification System (NAICS) industries with potential for significant 

occupational exposure. However, there are numerous other operations in which silica may be 

used or otherwise encountered, and it is important to be aware of the risk of silicosis in industries 

not previously recognized to be at risk.

History of Silicosis:

Silicosis is one of the world’s oldest known occupational diseases; reports of workers with the 

disease date back to ancient Greece. In 1938 the Department of Labor produced a film featuring 

then-Secretary of Labor Frances Perkins discussing the occurrence of silicosis among workers 

exposed to silica 

(see https://www.osha.gov/dsg/topics/silicacrystalline/health_effects_silica.html). The health 

effects associated with silica exposure are well-established. There were numerous common 

names for the lung disease now known as silicosis. The names frequently referred to the affected 

laborers’ trade, such as grinders’ asthma, grinders’ rot, masons’ disease, miners’ asthma, miners’ 

phthisis, potters’ rot, sewer disease, and stonemasons’ disease. 

 1 Every submission to the docket for the respirable crystalline silica rulemaking was assigned a document 

identification (Document ID) number that consists of the docket number (OSHA–2010–0034) followed by an 

additional four-digit number. These submissions can be found at http://www.regulations.gov.
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Despite its different names through the centuries, silicosis is a progressively disabling disease 

induced by the inflammatory effects of respirable crystalline silica in the lungs, which leads to 

lung damage and scarring and, in some cases, progresses to complications resulting in disability 

and death. 

Adverse Health Effects of Crystalline Silica Exposure:

Silica exposure is associated with a number of health effects, including silicosis (a disabling and 

irreversible lung disease), other non-malignant respiratory diseases (such as chronic bronchitis,

and emphysema), lung cancer, kidney disease, immunological effects, and activation of latent 

tuberculosis (TB) infections. Brief descriptions of some of these health effects are included 

below. For more information on silica-related health effects, see the preamble for the Final Rule 

for the Silica standards (81 FR at 16285, 16299 (3/25/2016)), plus the OSHA website’s Safety 

and Health Topics page on Silica. See also, NIOSH’s webpage on Silica.

Silicosis:

Silicosis is an irreversible, progressive disease induced by the inflammatory effects of respirable 

crystalline silica in the lung, leading to lung damage, scarring, and, in some cases, complications 

resulting in disability and death. Exposure to respirable crystalline silica is the only known cause 

of silicosis. Three types of silicosis have been described: An acute form following intense 

exposure to respirable dust of high crystalline silica content for a relatively short period (e.g., a 

few months or years); an accelerated form, resulting from about 5 to 15 years of heavy exposure 

to respirable dusts of high crystalline silica content; and, most commonly, a chronic form that 

typically follows less intense exposure of more than 20 years (Becklake, 1994, Document ID 

0294, Balaan and Banks, 1992, 0289,). In both the accelerated and chronic forms of the disease, 

lung inflammation leads to the formation of excess connective tissue, or fibrosis, in the lung. 

Once established, the fibrotic process of chronic silicosis is thought to be irreversible (Becklake, 

1994, Document ID 0294). There is no specific treatment for silicosis (Davis, 1996, Document 

ID 0998; Banks, 2005, Document ID 0291). Chronic silicosis is the most frequently observed 

type of silicosis in the U.S. today. Affected workers may have a dry chronic cough, sputum

production, shortness of breath, and reduced pulmonary function. 

Diagnosis:

The scarring caused by silicosis can be detected by chest X-ray or computerized tomography 

(CT) when the lesions become large enough to appear as visible opacities. The clinical diagnosis 

of silicosis has three requirements: Recognition by the physician that exposure to crystalline 

silica has occurred; the presence of chest radiographic abnormalities consistent with silicosis; the

absence of other illnesses that could resemble silicosis on a chest radiograph (e.g., pulmonary 

fungal infection or tuberculosis) (Balaan and Banks, 1992, Document ID 0289; Banks, 2005, 

Document ID 0291. A standardized system to classify opacities seen in chest radiographs was

developed by the International Labour Organization (ILO) to describe the presence and severity 

of silicosis on the basis of size, shape, and density of opacities, which together indicate the extent

severity and extent of lung involvement severity and extent of lung involvement
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(ILO, 1980, Document ID 1063; ILO, 2002, 1064; ILO, 2011, 1475; Merchant and Schwartz, 

1998, 1096; NIOSH, 2011, 1513.

Tuberculosis and Other Infections:

Silica exposed employees with latent TB are 3 to 30 times more likely to develop active

pulmonary TB infection (ATS 1997; Rees and Murray 2007). Although respirable

crystalline silica exposure does not cause TB infection, individuals with latent TB

infection are at increased risk for activation of disease if they have higher levels of

respirable crystalline silica exposure, greater profusion of radiographic abnormalities, or a

diagnosis of silicosis. Demographic characteristics, such as immigration from some countries, 

are associated with increased rates of latent TB infection. PLHCPs can review the latest Centers 

for Disease Control and Prevention (CDC) information on TB incidence rates and high risk 

populations online (see Section 5 of Appendix B to the silica standard). Additionally, silicaexposed employees are at increased risk for contracting nontuberculous mycobacterial infections, 

including Mycobacterium avium-intracellulare and Mycobacterium kansaii.

Chronic Obstructive Pulmonary Disease:

Epidemiologic studies have shown that occupational exposure to respirable crystalline silica is 

associated with chronic obstructive pulmonary disease, including bronchitis and emphysema. 

The findings from some of these studies suggest that emphysema and bronchitis may occur less 

frequently or not at all in nonsmokers. Epidemiologic studies have also found significant 

increases in mortality from non-malignant respiratory disease―a category that includes silicosis, 

emphysema, and bronchitis―as well as some other related pulmonary diseases [NIOSH, 2002].

Lung Cancer:

OSHA concluded that exposure to respirable crystalline silica increases the risk for lung cancer 

among workers. The conclusion is based upon a comprehensive weight of evidence review of 

more than 60 epidemiological studies covering more than 30 occupational groups in over a dozen 

industrial sectors and the rulemaking record as a whole (81 FR at 16302). The strongest 

evidence for carcinogenicity came from studies in five industry sectors: diatomaceous earth 

workers, British pottery workers, Vermont granite workers, North American industrial sand 

workers, and British Coal Miners (81 FR at 16306-16307). OSHA’s conclusion is consistent 

with classifications by the International Agency for Research on Cancer (IARC) and the National 

Toxicology Program (NTP). IARC (2012) concluded that ‘‘Crystalline silica in the form of 

quartz or cristobalite dust is carcinogenic to humans.’’ In the Ninth Report on Carcinogens, NTP 

concluded that “respirable crystalline silica, primarily quartz dust occurring in industrial and 

occupational settings, is known to be a human carcinogen” (NTP 2016).

Autoimmune Diseases:

Several epidemiologic studies have found statistically significant increases in mortality from or 

cases of immunologic disorders and autoimmune diseases in employees exposed to silica. These 

disorders and diseases include scleroderma (a rare multisystem disorder characterized by 
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inflammatory, vascular, and fibrotic changes usually involving the skin, blood vessels, joints, 

and skeletal muscle), rheumatoid arthritis, systemic lupus erythematosus (lupus), and sarcoidosis 

(a rare multisystem granulomatous disease characterized by alterations in the immune system) 

[NIOSH, 2002]. 

Renal Disease:

In addition to a number of case reports, epidemiological studies have found statistically

significant associations between occupational exposure to silica dust and chronic renal disease 

(Calvert et al., 1997, Document ID 0976), subclinical renal changes (Ng et al., 1992c, Document 

ID 0386), end-stage renal disease morbidity (Steenland et al., 1990, Document ID 1125), chronic 

renal disease mortality (Steenland et al., 2001b, Document ID 0456; 2002a, 0448), and 

granulomatosis with polyangitis (also known as Wegener’s granulomatosis), a condition that can 

affect the kidneys (Nuyts et al., 1995, Document ID 0397). In other findings, silica-exposed

individuals, both with and without silicosis, had an increased prevalence of abnormal renal 

function (Hotz et al., 1995, Document ID 0361), and renal effects have been reported to persist

after cessation of silica exposure (Ng et al., 1992c, Document ID 0386). 

Summary:

As these health findings indicate, respirable crystalline silica exposure is associated with a 

number of diseases in addition to silicosis. Due to the lack of evidence of health hazards from 

dermal or oral exposure, OSHA focused solely on those studies associated with airborne

exposure to Silica.

Silica exposure continues to pose substantial risks to employees, centuries after it was first 

identified as an occupational hazard. Reducing exposures to silica through engineering and work 

practice controls decreases the risk of developing silica-related diseases.

References:

Beckett, W., et al. (1997) Adverse Effects of Crystalline Silica Exposure. Statement of the American 

Thoracic Society, Medical Section of the American Lung Association. American Journal of 

Respiratory and Critical Care Medicine. 155:761-765. 

Bergen, E.A.V.D., Rocchi, P.S.J., Boogaard, P.J. (1994) Ceramic Fibers and other Respiratory 

Hazards during the Renewal of the Refractory Lining in a Large Industrial Furnace. Appl. Occup. 

Environ. Hyg. 9(1):32-35. 

Cheng, R.T., McDermott, H.J., Gia, G.M., et al. (June 1992) Exposure to Refractory Ceramic Fiber 

in Refineries and Chemical Plants. Appl. Occup. Environ. Hyg. 7(6):361-367. 

Davis, G.S. (1996) “Silica,” in Occupational and Environmental Respiratory Disease, Mosby–

Yearbook Inc., St. Louis, Mo, eds. Harber, P., Schencker, M.B., Balmes, J.R. 

Gantner, B.A. (1986) Respiratory Hazard from Removal of Ceramic Fiber Insulation from High 

Temperature Industrial Furnaces. Am. Ind. Hyg. Assoc. J. 47(8):530-534. 
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IARC. (1997) IARC Monographs on the Evaluation of Carcinogenic Risks to Humans. Silica, Some 

Silicates, Coal Dust and para-Aramid Fibrils. Vol. 68. Lyon, France. International Agency for 

Research on Cancer, World Health Organization. 

International Agency for Research on Cancer (IARC). (2012). Monographs on the evaluation of 

carcinogenic risks to humans: Arsenic, Metals, Fibers, and Dusts Silica Dust, Crystalline, in the 

Form of Quartz or Cristobalite. A Review of Human Carcinogens. Volume 100 C. Geneva, 

Switzerland: World Health Organization.

National Toxicology Program (NTP) (2016). Report on Carcinogens, Fourteenth Edition. Silica, 

Crystalline (Respirable Size). Research Triangle Park, NC: U.S. Department of Health and 

Human Services, Public Health Service. (see 

https://ntp.niehs.nih.gov/ntp/roc/content/profiles/silica.pdf)

Rosner, D., Markowitz, G. (1994) Deadly Dust: Silicosis and the Politics of Occupational 

Disease in Twentieth-Century America. Princeton: Princeton University Press.

U.S. EPA. 1996. Ambient Levels and Noncancer Health Effects of Inhaled Crystalline Silica -

Health Issue Assessment. United States Environmental Protection Agency, Office of Research 

and Development, Washington DC 20460. EPA/600/R-95/115.

U.S. Department of the Interior. 1992. Crystalline Silica Primer. United States Department of the 

Interior, U.S. Bureau of Mines, Branch of Industrial Minerals. RC 965.S5C79 1992.
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Appendix E

Employee Questionnaire for use by CSHOs (Non-mandatory)

Note for CSHOs: This questionnaire, when completed, may be considered a medical record and 

must be used in accordance with § 1913.10 - Rules Concerning OSHA Access to Employee 

Medical Records. This questionnaire is intended to supplement guidance to Section IX.J of this 

Instruction when CSHOs are interviewing employees to evaluate the employer’s medical 

surveillance program. CSHOs should consult with the OSHA Office of Occupational Medicine

and Nursing (OOMN) regarding any findings of potential silicosis. The CSHO should also 

consult with the OOMN to determine whether there is a need for a medical access order. 

Date: Company Name: Location:

A. Personal Information

Employee’s Name: Gender:  Male  Female

Current Job Title: Age: 

B. Job-Related Information

Number of hours worked in silica-related tasks 

per week:

List previous jobs and duration of each job:

 10-20 a. ( yrs.)

 20-30 b. ( yrs.)

 30-40 c. ( yrs.)

 More than 40 ( hours) d. ( yrs.)

Time at current job:

 Six months or less

 1-2 yrs

 3-5 yrs

 More than 5 yrs. ( ______ yrs.)

How many days per year do you work in a silica-related task? _____ days.

How many days per year do you need to wear a respirator due to work in a silica-related task? 

_____ days.

C. Brief Medical History

Are you being treated by a physician for breathing problems?  Yes  No

Have you ever had a chest X-ray?  Yes  No

If yes, when was your last chest X-ray?

Why was the chest X-ray taken?

Did the doctor tell you everything was normal?  Yes  No

If no, what was noted?

What treatment are you receiving for this 

problem?

Have you discussed your medical history with your employer?  Yes  No

Are you a cigarette smoker?  Yes  No
F-1

Appendix F

CSHO Checklists for Respirable Crystalline Silica Inspections

These non-mandatory checklists are intended to be a quick reference tool for a Compliance 

Safety and Health Officer (CSHO) conducting silica-related inspections. 

General Industry / Maritime Checklist

Exposure Assessment

 Exposures correctly assessed

 Performance option w/ monitoring or 

objective data (under conditions closely 

resembling or higher exposure 

potential), before work begins

 Scheduled monitoring option represents 

each job, work area and shift, as soon as 

work begins

 New or additional exposures reassessed 

 Employees notified of results within 15 

working days

 Sample analysis compliant w/Appendix 

A

Regulated Areas

 Reasonably expected to exceed PEL

 Demarcated; signs at entrance

 Access limited; respirators provided

Methods of Compliance

 Feasible engineering controls and work 

practices used; respirators if needed

 Abrasive blasting also complies with 29 

CFR §§ 1910.94, 1915.34, 1915 Subpart 

I, as applicable

Hydraulic Fracturing

 Type and source of proppant

 Compliant with all provisions by 

6/23/2018, except as follows:

 Engineering controls implemented 

by 6/23/2021

Medical Surveillance

 Medical surveillance for employees 30 

days a year at or above AL (began 

6/23/2020)

(cont.)

 

Construction Checklist

Table 1 - Specified Exposure Control 

Methods 

 Equipment/task identified

 Controls fully and properly 

implemented; if not, collect air 

sample

 Manufacturers’ instructions followed

 Water spray at point of dust 

generation at sufficient flow rates

 Adequate supply of water is on site

 Dust collectors commercially 

available and meet reqd. CFM and 

99% filter efficiency

 Means of exhaust for tasks indoors/in 

enclosed areas

 Enclosed cab doors sealed properly

 All engaged workers wearing 

specified respirators, APF of 10 or 25, 

if required

 Do multiple tasks add to > 4 hours? 

If yes, is the required respiratory 

protection used, if any?

[Or]

Alternative Exposure Control Methods

 Exposures correctly assessed

 Performance option w/ monitoring or 

objective data (under conditions closely 

resembling or higher exposure potential), 

before work begins

 Scheduled monitoring option represents 

each job, work area and shift, as soon as 

work begins

 New or additional exposures reassessed 

 Employees notified of results within 5 

working days

 Sample analysis compliant w/ Appendix 

A

 Feasible engineering controls and work 

practices used; respirators if needed

 Abrasive blasting also complies with 29 

CFR § 1926.57

(cont.)
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Construction Checklist (cont.)

Communication of Hazards

 Includes silica in HAZCOM program

 Employees knowledgeable of standard, 

health hazards, workplace exposures, 

protective measures, medical 

surveillance

 Copy of standard available at no cost 

 Employees identified competent person

Recordkeeping

 All air monitoring and objective data

 Info provided to PLHCPs and 

specialists

 PLHCPs’ and specialists’ medical 

opinions

 Maintained and available per 29 CFR § 

1910.1020

Gen. Industry / Maritime Checklist 

(cont.)

Communication of Hazards

 Includes silica in HAZCOM program

 Employees knowledgeable of standard, 

health hazards, workplace exposures, 

protective measures, medical 

surveillance

 Copy of standard available at no cost 

 Correct signage at regulated areas

Recordkeeping

 All air monitoring and objective data

 Info provided to PLHCPs and 

specialists

 PLHCPs’ and specialists’ medical 

opinions

 Maintained and available per 29 CFR § 

1910.1020
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Appendix G

Hydraulic Fracturing Background

A. Background: Hydraulic fracturing or “fracking” is a process used to stimulate well 

production in the oil and gas industry. It is not a new process, but its use has increased 

significantly because of new horizontal drilling and multi-stage fracking (or 

“completions”) technologies that improve access to natural gas and oil deposits. It 

involves pumping large volumes of water and sand into a well at high pressure to fracture 

shale and other tight formations, allowing oil and gas to flow into the well. Silica sand 

used as a proppant contains a high percentage of crystalline silica, typically ranging from 

60 to 100 percent depending on the source. When silica sand is used as a proppant in 

hydraulic fracturing, high airborne concentrations of respirable silica dust can occur as 

workers deliver, convey, and mix large volumes of sand with fracturing fluid. 

The following locations or equipment are the primary sources of dust emissions on 

fracturing worksites:

1. Dust emitted from thief hatches (open ports on the top of the sand movers used to 

allow access into the bin);

2. Dust ejected and pulsed through side fill ports on the sand movers during refilling 

operations;

3. Dust released from:

a. transfer belt under the sand movers;

b. operations of transfer belts between the sand mover and the blender;

c. top of the dragon’s tail (end of the sand transfer belt) on sand movers;

4. Dust created as sand drops into, or is agitated in, the blender hopper and on 

transfer belts;

5. Dust generated by on-site vehicle traffic, including sand trucks and crew trucks, 

by the release of air brakes on sand trucks, and by winds.

See Technical Feasibility document (Chapter 4.22, Hydraulic Fracturing), for 

further information.

B. Fracturing Inspection Guidelines: CSHOs should review the employer’s records and/or 

interview the employer and employees to determine the following:

Note: The inspection procedures that are outlined in Section IX of this Instruction apply 

to fracturing inspections.

1. Type and Source of Proppant: 
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Determine the following regarding the proppant being used:

a. Silica content (from safety data sheet, if available).

b. Quantity of proppant (per day, per shift, or per job task).

c. Possible heavy metal contamination.

d. Proppant particle size.

e. Make-up of the proppant solution.

Proppant consists of particles that hold open the fractures created by hydraulic 

fracturing, allowing the oil and gas to flow out of the formation and into the well 

bore. Silica sand is frequently used as a proppant. Other proppants can include

sintered bauxite or ceramics, and resin-coated sand.

2. Exposure Assessment: Review the employer’s silica exposure assessment for 

compliance with 29 CFR § 1910.1053(d)(1). Assess the following:

a. Tasks/operations that are likely to exceed the AL and/or the PEL.

b. Employer exposure reassessments.

c. Appropriate method of sampling analysis.

d. Regulated area included “at risk” tasks/operations.

e. Employee notification of the results from the exposure assessment.

f. Date of employee notification.

3. Regulated Areas: Evaluate the employer’s regulated area to ensure that it meets 

the following requirements of 29 CFR § 1910.1053(e)(2) and (e)(3):

a. Effective demarcation and signage with appropriate warning language.

b. Effective protocol to limit access into the regulated area.

c. Designated authorized personnel. 

4. Engineering Controls: Evaluate what types of engineering controls are being used 

to limit employees’ exposure following 29 CFR § 1910.1053(f)(1).

Note: Employers have until June 23, 2021, to be in compliance with this 

paragraph. The CSHO should collect the following information regarding the 

controls:

a. Local Exhaust Ventilation Unit:

o Make, model, and rated air moving capacity (CFM) at a given static 

pressure.

o Diameter and length of ductwork.

o Proppant transport velocity (FPM) inside the duct (goal is 3,500 FPM).

o Design and actual static pressure drop across the filter for the 

ventilation system (inches of water).

o Filtration efficiency (e.g., HEPA filter); location of system exhaust.

o Method of disposal of captured proppant.

b. Proppant Loading and Moving Equipment:

o Equipment staging plan with operational parameters.

o Type of proppant loading equipment (gravity vs. pneumatic feed).
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o Pneumatic loading parameters of proppant to sand movers―feed rate 

and feed pressure (PSI).

o Methods and effectiveness of dust controls at conveyor belt transfer 

points.

o Excessive proppant conveyor feed rates causing spillage.

o Locations of work stations.

c. Mobile Equipment, Change Trailers and Work Trailers:

o Efficiency of HVAC filtration system―standard HVAC filters are 

coarse and not designed to remove respirable particulate. 

5. Administrative Work Practices: Evaluate administrative controls that are being 

used by the employer to limit employees’ exposure. Administrative controls 

could include, for example:

a. Minimizing accumulation inside changing trailers, work trailers, and cabs 

of mobile equipment.

b. Restricting workers not engaged in a silica task from accessing or 

continually standing and working close to silica dust sources.

c. Ensuring proper doffing of contaminated personal protective equipment 

(e.g., coveralls).

6. Equipment Maintenance Program: Proper equipment maintenance will greatly 

reduce sources of dust emissions. CSHOs should check for:

a. Cap and cover all unused ports and hoses on proppant handling and 

moving equipment.

b. Repair holes worn in equipment due to sand abrasion.

c. Ensure that all enclosures used for dust control are in good condition and 

are not leaking.

d. Ensure that the fall distance between conveyor transfer points and hoppers 

is kept to a minimum.

e. Ensure that all exhaust ventilation ducts are in good condition.

f. Ensure that the exhaust ventilation unit is operating as designed and within 

the appropriate static pressure range. 

g. Ensure that the final filter and seals on the exhaust ventilation system are 

in good condition.

Ensure that the environmental cabs for mobile equipment are properly maintained 

(door seals, HVAC system, windows, condition of cab door).

Note: The silica standards do not prohibit the rotation of employees (a type of 

administrative control) to limit employee exposures. However, this practice is 

discouraged as a means of avoiding implementation of engineering and other 

work practice controls, due to potential difficulty maintaining employees’ 

exposures at/or below the PEL solely using rotation. Moreover, the use of 
G-4

rotation may require the employer to provide medical surveillance to additional 

workers and to train many workers on multiple jobs (see GI FAQ # 30).

7. Fugitive Dust Controls: Evaluate measures taken by the employer to control 

fugitive dust from the drill pad and roadways. Examples:

a. Use of water and surfactants.

b. Frequency of application.

8. Written Exposure Control Plan: Review the employer’s exposure control plan to 

ensure that it contains the minimum requirements as outlined in 29 CFR §

1910.1053(f)(2): 

a. Description of the tasks that involve silica exposure.

b. Description of engineering controls, work practices, and respiratory 

protection.

c. Description of housekeeping measures.

d. Annual review of exposure control plan.

e. Availability of written ECP to covered employees.

9. Respiratory Protection Program: Evaluate the employer’s respiratory protection 

program and its implementation in accordance with 29 CFR § 1910.134.

a. Selected respirator is used within its assigned protection factor.

b. Respirator cartridge efficiency requirements (P-100, HEPA filtration).

c. Medical evaluation and fit testing.

d. Proper use and maintenance of respiratory protection.

10. Housekeeping and Work Practices: Evaluate whether the employer allows:

a. Use of compressed air to remove dust from clothing.

b. Dry sweeping that contributes to worker exposures.

C. General:

1. Observations:

a. Document the silica-related activities observed while on site.

b. Dust sources and their specific cause.

c. Effectiveness of engineering controls.

d. Employee work practices and personal protective equipment (PPE).

e. Location of regulated area and the exclusion (red) zone.

f. Enforcement of the regulated and the exclusion zones.

g. Weather conditions. 

h. Size of well pad.
G-5

Note: Know and follow the employer’s exclusion zone (red zone) (example 

below) for the hydraulic fracturing site, which allows only essential workers 

within the specified zone. The exclusion zone contains pressurized pipes and 

related equipment that present potential struck-by hazards if a connection failure 

were to occur during fracturing operations. The exclusion zone does not

necessarily equate to the silica regulated area. Do not enter the exclusion zone 

during fracturing operations. The exclusion zone can be 1.5 to 2 times (or 

company’s policy) the swing radius of a length of pipe. The exclusion zone 

should have demarcation, signage, barriers, restrictions, or other methods to 

control access. CSHOs should refer to the company’s policies and procedures 

and review the company’s hazard assessment prior to site entry. 

2. Third Party Contractors: Document third-party contractors who provide 

hydraulic fracturing services at the well site. 

a. Dust control and disposal services

b. Proppant suppliers 

c. Equipment maintenance (including maintenance performed at offsite locations).

D. CSHO Personal Protective Equipment:

1. CSHOs assigned to conduct silica monitoring at hydraulic fracturing sites must

be approved to wear at least an air-purifying half-mask respirator equipped with 

P-100 cartridges. The CSHO must have passed a medical evaluation/respirator fit 

test within the previous year.

2. Other required personal protective equipment is fire-retardant (FR) clothing, 

including a FR high visibility vest; hard hat, eye and foot protection.

E. CSHO Equipment:

1. CSHOs should be equipped with a multi-gas meter for oxygen, LEL, carbon 

monoxide, and hydrogen sulfide. If your multi-gas meter does not test for 
G-6

hydrogen sulfide, then the CSHO will need a hydrogen sulfide air monitor.

2. CSHOs should also refer to OSHA Publication 3763, Hydraulic Fracturing and 

Flowback Hazards Other than Respirable Silica Guide, for more information 

about hydraulic fracturing and flowback operations hazards. The guide can be 

found at https://www.osha.gov/Publications/OSHA3763.pdf.
H-1

Appendix H

Additional Guidance and Resources

CSHOs may find useful additional guidance and resources available from CPWR - The Center 

for Construction Research and Training (CPWR). The CPWR information can be found at

https://www.silica-safe.org/. In particular, alternate names of tools and equipment can be found 

in the CPWR’s Training and Other Resources webpage.