DLLR's Division of Labor and Industry


MOSH Instruction 08-07 - Maryland Occupational Safety and Health (MOSH)

Subject: National Emphasis Program (NEP) Crystalline Silica w/ Addendum
Effective Date: October 1, 2008
Issuance Date: November 20, 2008
Cancellation: None
Purpose: The purpose of this Instruction is to significantly reduce /eliminate employee overexposures to crystalline silica and, therefore, control the health hazards associated with such exposures. This Instruction describes policy and procedures for participating in OSHA's National Emphasis Program to identify and reduce or eliminate the health hazards associated with occupational exposure to crystalline silica.
Scope: This instruction applies MOSH-wide
Reference: OSHA Instruction, Directive Number CPL 03-00-007, January 24, 2008, National Emphasis Program - Crystalline Silica
Action: MOSH Regional and Consultation Supervisors shall ensure that all staff is trained in the contents of this instruction.
Contact: Chief of MOSH Compliance Services
312 Marshall Avenue, Room 602
Laurel, Maryland 20707
(410) 880-4886 x312
By and Under the Authority of: Roger Campbell, Assistant Commissioner


Crystalline silica is an important industrial material, and occupational exposure occurs in a variety of workplace settings, including mining, manufacturing, construction, maritime, and agriculture. Processes associated historically with high rates of silicosis include sandblasting, sand-casting foundry operations, mining, tunneling, cement cutting and demolition, masonry work, and granite cutting. Appendix A provides further information on silica, including sources, industrial uses, and adverse health effects. Appendix B provides a list of North American Industrial Classification System (NAICS) and Standard Industrial Classification (SIC) codes for industries in which silica exposure occurs frequently, based on a review of OSHA inspection data for the period 1996 to 2007.

Reducing and ultimately eliminating the workplace incidence of silicosis has been a primary goal of the Agency since its inception. In 1972, OSHA issued guidelines for conducting inspections in workplaces with significant crystalline silica exposure. In the early 1980s, the Agency placed a special emphasis on the prevention of silicosis in foundry personnel, and in 1996 OSHA implemented a Special Emphasis Program (SEP) to reduce the workplace incidence of silicosis.

The 1994 Government Performance and Results Act (GPRA) mandates that federal agencies improve performance and devise a system for measuring results. To comply with the provisions of GPRA, OSHA developed a Strategic Plan for improving the safety and health of all employees. In 1998 and again in 2003, under the Strategic Plan, OSHA identified crystalline silica as one of the focused hazards.

This NEP is being implemented to direct OSHA's field staff inspection efforts to address elevated silica exposures in the workplace, including General Industry (1910) and Construction (1926). These efforts meet the Strategic Plan goal of reducing silicosis, set forth by the Agency.


cc: J. Ronald DeJuliis, Commissioner, Division of Labor and Industry
Craig D. Lowry, Deputy Commissioner, Division of Labor and Industry
Jonathan R. Krasnoff, Deputy Counsel, Department of Labor, Licensing and Regulation
Office of Administrative Hearings


MOSH Instruction 08-7
National Emphasis Program (NEP) - Crystalline Silica

I. National Emphasis Program Goals.

The purpose of this NEP is to significantly reduce/eliminate employee overexposures to crystalline silica and, therefore, control the health hazards associated with such exposures. This goal will be accomplished by a combined effort of inspection targeting, outreach to employers, and compliance assistance.

Inspections should be targeted to work sites that likely create high silica exposures. In each Region, at least 2 percent of inspections every year should be silica-related inspections. Additionally, the silica-related inspections should be conducted at a range of facilities reasonably representing the distribution of general industry and construction work sites in that region.

To ensure abatement and measure the effectiveness of this NEP, follow-up site visits often will be necessary as outlined in Section XI(D.) below.

II. Program Procedures.

A. NEP Inspections

Inspections conducted under this NEP will focus on industries where employees are potentially exposed to levels of crystalline silica in excess of the permissible exposure limit (PEL). Appendix B, which was developed from OSHA inspection data, lists industries with potential silica exposure and provides an overview of the types of industries in which silica exposures frequently occur.

1. Industry Selection

The Chief of Compliance, or designee, will identify the industry sectors that are to be targeted by the Regional Offices and shall then prepare a master list of NAICS codes from those listed in Appendix B. The rationale for selecting each industry shall be documented, and may include information such as, but not limited to:

a. History of overexposures, based on previous local inspection history within a Regional Office's jurisdiction of industries listed in Appendix B.

b. Limited or no local inspection history of an industry listed in Appendix B.

c. The Chief of Compliance, or designee, may establish knowledge of a pattern of silicosis or overexposures to silica by reviewing objective illness or exposure data from any and all sources including, state workers' compensation records or public health data from sources such as the National Institute for Occupational Safety and Health (NIOSH).

d. Industries that are not included in Appendix B, but are known by the Chief of Compliance, Assistant Chief, or Regional Supervisor, based on local knowledge (i.e. a documented history of referrals from local agencies or healthcare providers, or previous inspection histories, etc.), to have demonstrated a pattern of silica overexposures or cases of silicosis.

2. Site Selection and Scheduling

a. General Industry

The Chief of Compliance, or designee, shall develop a list of general industry establishments in Maryland that fall within the NAICS codes listed in Appendix B. Establishment sources may include:

1. The Harris Directory of Maryland Employers;
2. Commercial directories;
3. Telephone listings;
4. Knowledge of establishments.

After identifying the relevant general industry establishments, those establishments shall be incorporated into Maryland's High Hazard Industries LEP (MOSH Instruction 08-9) inspection list for each Region using a random number table.

Any general industry establishment that has a NAICS code that falls outside of those industries identified in MOSH Instruction 08-9, Maryland's High Hazard Industries, will be place on the inspection list, however the inspection will be conducted focused on only the hazards related to silica.

b. Construction

Construction inspection shall be scheduled from a list of work sites rather than construction employers, in accordance with MOSH Instruction 08-3, Inspection Scheduling Criteria for Construction. If during the course of any construction inspection a Compliance Safety & Health Officer (CSHO) encounters a site that falls within any of the NAICS listed in Appendix B, that inspection shall also focus on any activity(s) that potentially exposes employees to silica.

c. Deletions

Based on their familiarity with local industries, Regional Supervisors in conjunction with the Chief of Compliance, or designee, shall delete from the master list any establishment known to be out of business. The Regional Office will document the basis for the determination.

The Regional supervisors in conjunction with the Chief of Compliance, or designee, shall also delete any establishment that has had an inspection where employee exposures to silica have been evaluated within the previous three (3) years, provided either that no serious violations related to silica exposures were cited or that serious violations were cited but a follow-up inspection documented effective abatement of the cited conditions.

d. Additions

Whenever an office becomes aware of a previously unknown establishment in one of the identified NAICSs, Regional Supervisors in conjunction with the Chief of Compliance, or designee, shall add that establishment to the appropriate High Hazard Industry list for inclusion in the next inspection cycle.

3. Complaints and Referrals

Detailed guidance regarding polices and procedures when conducting complaints and referrals inspections is provided in MOSH Instruction 08-2, Complaint and Referrals.

4. Deferrals

An establishment that has requested an initial full-service comprehensive consultation visit for safety or health from the MOSH Consultation Program, and that visit has been scheduled by Consultation may be deferred from the inspection for 90 calendar days from the date of notification by MOSH Consultation Program to the Regional Office. No extension of the deferral beyond the 90 calendar is possible, unless the consultation visit is "in progress" which begins at the opening conference of the consultation visit. See 29 CFR 1907.7(b)(1) for a definition of "in progress".

If an establishment is in the process of applying for MOSH's Voluntary Protection Program (VPP), the Chief of Compliance, upon receiving notification from the VPP Manager that a VPP on-site review has been scheduled, will defer any programmed inspection. The applicant workplace will be deferred starting no more than 75 days prior to the commencement of its scheduled pre-approval on-site review. The applicant workplace will be removed from any programmed inspection list for the duration of VPP participation, unless the site chooses otherwise.

If an establishment is in pre-Sharp status, that is in the process of meeting the criteria of a MOSH Consultation Safety and Health Achievement Recognition Program (SHARP), it may be deferred for up to 18 months, while the employer is working to achieve recognition and exemption status. See 29 CFR 1908.7(b)(4)(i)(A).

If an establishment is an approved participant in MOSH's Voluntary Protection Program (VPP), in MOSH Consultation's Safety and Health Achievement Program (SHARP), or Cooperative Compliance Partnership (CCP) program it is to be deleted from the inspection list.

5. Expanding Scope of Inspection:

The Compliance Safety and Health Officer (CSHO) may expand the scope of a NEP inspection beyond the silica-related activities if other hazards or violations are observed, following the guidelines set forth in the FOM.

B. Inspection Procedures.

This section outlines procedures for conducting inspections and preparing citations for silica-related violations. For further guidance, the CSHO should consult the OSHA directives, appendices, and other references provided below. Appendix H contains a checklist that summarizes the information to be documented during a silica-related inspection. The checklist may be used by the CSHO to ensure proper coverage of the essential elements of a silica-related inspection.

1. Employee Exposure Monitoring

a. Conduct monitoring to determine employee exposure to respirable dust containing crystalline silica, in accordance with the OSHA Technical Manual (OTM), Section II, Chapter 1 and OSHA method ID-142. Appendix C contains guidelines on collecting air samples and Appendix D summarizes procedures for performing leak tests on cyclones.

b. Obtain bulk samples of settled dust from silica operations, in accordance with the OTM, Section II, Chapters 1 and 4.

c. Review any existing employer's silica exposure monitoring records.

Citation Guidance: When the PEL for respirable dust containing silica is exceeded (regardless of the use of PPE), the CSHO should cite 1910.1000(c) or 1926.55(a) for the relevant industry in accordance with the Field Operations Manual (FOM); Chapter IV, Section 5.

For construction, exposures are not based on the general industry PEL, but are determined gravimetrically and converted to mppcf and should therefore be cited as exceeding the construction PEL in mppcf. Appendix C contains guidance on calculating the general industry PEL, and Appendix E provides information on calculating the construction and maritime industry PELs for crystalline silica.

2. Engineering and Work Practice Controls

a. Document and evaluate any engineering and work practice controls in place intended to reduce exposure to respirable crystalline silica, such as:

1. Location of employee(s) with respect to dust generation source.

2. Isolation (e.g., control room, enclosures, or barriers).

3. Local exhaust ventilation (LEV) systems.

4. Wet methods for cutting, chipping, drilling, sawing, grinding, etc.

5. Use of HEPA-equipped vacuums or wet sweeping for cleaning.

6. Employers should be advised not to use compressed air for cleaning silica contaminated surfaces.

7. Substitution with non-crystalline silica material.

8. Use of tools with dust collecting systems.

Controls for abrasive blasting are addressed further in Section II (B)(7), below.

b. Guidelines for investigations of ventilation systems are contained in the OTM, Section III Chapter 3.

Citation Guidance: If an employer fails to implement feasible engineering or work practice controls for reducing respirable crystalline silica exposures to levels less than the PEL, the CSHO should cite 1910.1000(e), 1926.55(b), or 1926.57(a) and (b), as appropriate. Guidance on what constitutes feasible administrative, work practice, and engineering controls is provided in the MOSH Field Operations Manual (FOM); Chapter III, Section E .6. Information is also available on the OSHA website.

Subsequent citations may not be appropriate when all of the following conditions have been met:

1. the employer has fully implemented the feasible means of abatement recommended in the previous citation;

2. the employer has fully implemented a respiratory protection program;

3. applicable engineering controls used to address the hazard have not significantly advanced since the previous citation.

Under these conditions, the Regional Office shall contact the Chief of Compliance for guidance. (Note: This policy is limited to situations where the employer has made good faith efforts to comply with the silica exposure limit by implementing engineering controls previously suggested by the MOSH but which have not reduced exposures below the PEL. In such situations requiring the employer to continue to implement additional controls which may not reduce the exposures below the PEL may be inappropriate.)

3. Respiratory Protection

a. Detailed inspection and citation guidance related to respiratory protection is contained in OSHA Instruction 02-00-120 (CPL 2-0.120) - Inspection Procedures for the Respiratory Protection Standard.

b. Minimum Respiratory Protection: When respirators are a permissible means to address overexposure, the minimum respiratory protection for employees exposed to crystalline silica during operations, other than abrasive blasting, is the N95 NIOSH-approved respirator for exposures that do not exceed the assigned protection factor.

c. Medical Evaluations for Respirator Use: Medical evaluations must be given to all employees required to wear a respirator, however, medical evaluations are not required for employees who voluntarily use filtering face-piece respirators (dust masks). Employees who refuse to be medically evaluated cannot be assigned to work in areas where they are required to wear a respirator.

4. Hazard Communication

a. Detailed inspection and citation guidance related to hazard communication is contained in OSHA Instruction CPL 02-02-038 (CPL 2-2.38D)-Inspection Procedures for the Hazard Communication Standard.

b. Labeling of Carcinogens: Information regarding evidence of carcinogenicity must be included on container labels and Material Safety Data Sheets (MSDSs) for crystalline silica, and for products containing crystalline silica. Carcinogen warnings are required on containers of materials containing more than 0.1 percent crystalline silica by weight or volume, as determined by analysis of a bulk sample of the original product. The CSHO should collect bulk samples to determine silica content if MSDSs appear inadequate or incomplete.

c. Bricks/Tiles/Cement boards: Bricks, tiles and cement boards containing silica fall under the requirements of the Hazard Communication standard (HCS) due to the hazards associated with silica. Under normal conditions of use, bricks, tiles and cement boards are cut, sawed, or drilled, generating airborne levels of crystalline silica that could result in elevated exposures and are therefore not considered to be exempt under the HCS as articles. Note: Bricks do not need to be individually labeled. Bricks that are palletized and bound by metal bands are considered to be containers and are to be tagged with an appropriate label.

d. Crushed Stone: Vehicles hauling shipments of crushed stone shall include hazard warnings concerning the carcinogenicity of crystalline silica on their shipping papers or bills of lading. CSHOs should initially determine whether the Mine Safety and Health Administration (MSHA) or MOSH has jurisdiction over the specific crushed stone operation.

5. Housekeeping and Hygiene Practices

a. Determine whether the employer's housekeeping and hygiene practices may contribute to overexposure. For example:

1. Exposed surfaces should be as free as practicable of silica-containing dust (bulk samples of the dust may need to be collected).

2. Contaminated surfaces should not be blown clean with compressed air or other forced air (such as leaf blowers).

3. Wet sweeping should be used to clean areas if possible.

4. If vacuuming is used for cleaning, the exhaust air should be properly filtered to prevent release of airborne silica back into the workroom.

5. There should be separate break areas for consuming food, beverages, etc. that are kept free of silica.

6. Clothes contaminated with silica should not be blown or shaken to remove dust.

b. Document poor housekeeping and hygiene practices.

Citation Guidance: If employees are overexposed to crystalline silica, and poor housekeeping practices are noted, the CSHO should cite, as applicable, 1910.141, 1926.51(f), or 1926.51(g).

6. Employee Exposure and Medical Records

a. Interview employees to determine whether they understand their right to review their medical and exposure records, as well as their rights regarding the confidentiality of such records.

b. Review the employer's recordkeeping program to ensure that the required information is being collected and reported.

c. Evaluate the employer's method for ensuring the confidentiality of employee medical records.

d. When it is necessary to review employee medical records, ensure that they are obtained and remain confidential in accordance with 1913.10 and 1910.1020.

Citation Guidance: If violations are found, CSHOs should cite the applicable section of 1910.1020 or 1926.33. These rules do not require creation of any records, only preservation and access requirements.

Recent revisions to recordkeeping policies and procedures are described in CPL 02-00-135, Recordkeeping Policies and Procedures Manual (RKM).

7. Abrasive Blasting:

In addition to the program elements described above, the following procedures apply specifically to abrasive blasting operations:

a. Conduct monitoring to determine employee exposure to metals, such as: lead, arsenic, 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.)

b. The air sampling device (cyclone) must be placed within the breathing zone, outside of any protective equipment including the abrasive blasting hood.

c. Conduct exposure monitoring of potentially exposed employees not engaged in abrasive blasting but still working in the area.

d. Conduct noise exposure monitoring as appropriate.

e. Determine whether the ventilation systems for abrasive blasting rooms and containment structures prevent escape of dust and provide prompt clearance of dust-laden air.

f. Determine whether each blast cleaning nozzle is properly equipped with an operating valve that must be held open manually.

g. 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 the PEL. [Note: Using an abrasive blasting hood while wearing a filtering face piece respirator violates the NIOSH approval for both respirators.]

h. When compressors are used to supply air, ensure that in-line absorbent beds are used and maintained.

i. Review electrical grounding.

j. Review pressure controls.

k. Determine whether the abrasive blasters have adequate PPE, such as canvas or leather gloves and aprons, to protect against injury from material impact.

l. Where an alternative abrasive material is being used 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.

Citation Guidance: If overexposures to metals or noise are found, the CSHO should cite the applicable standard.
If the ventilation system for a blast cleaning enclosure is found to be inadequately designed or ineffective at controlling dust, the CSHO should cite the applicable section of 1910.94(a).

If blast cleaning nozzles are not properly equipped with operating valves that must be held open manually, the CSHO should cite 1910.244(b) or 1926.302(b)(10).

Violations related to respiratory protection for abrasive blasting operations may be cited under 1910.94(a)(5). Guidance is also contained in OSHA Directive CPL 02-00-120 (CPL 2-0.120), Inspection Procedures for the Respiratory Protection Standard.

Violations related to personal protective equipment should be cited under 1910.94(a)(5), 1910.132, 1926.28, 1926.95, or 1926.100-103.

C. Outreach.

The OSHA Office of Training and Education, in conjunction with the Directorate of Enforcement Programs and the Office of Communications, will develop crystalline silica-related information and training materials. This information will be obtained from OSHA and made available to the MOSH Compliance and Consultation Offices as well as the public through seminars, booths, materials requests forms and site visit resources. In addition we will continue to hold seminars that address silica identification, dangers, and solutions during our public seminars in related courses such as Industrial Hygiene for Construction and basic General Industry courses.

D. Follow-up and Monitoring.

1. Where citations are issued for overexposure to crystalline silica, follow-up site visits must be conducted to determine whether the company is eliminating silica exposures or reducing exposures below the PEL. Where exposures can not feasibly be reduced below the PEL, engineering and administrative controls must be used to reduce exposures to the extent feasible and employees protected with the use of PPE.

2. For those employers where follow-ups cannot be done, (i.e., construction sites or temporary abrasive blasting operations) the Regional Office should request that the employer provide written updates documenting the progress of their abatement efforts per 1903.19.

E. IMIS Coding Instructions.

For each form that has a Strategic Plan field, "SILICA" will be entered in that field for all inspections.

For inspections which are conducted under this NEP, for each form that has an NEP field, enter "SILICA" in the appropriate field (see below).

Additionally, for situations where crystalline silica is used as the abrasive media when abrasive blasting, Optional Information "ABRASIVE" will be entered on all forms (see below).



NEP Field

Optional Information

Strategic Plan























































Consultation: Recording silica related visits will be done whenever a visit is made in response to this NEP. For each form that has an NEP field, enter "SILICA" for situations where crystalline silica is used. For situations where crystalline silica is used as the abrasive media when abrasive blasting, Optional Information "ABRASIVE" will be entered on all forms (see below).



NEP Field

Optional Information








Request Form-20







Visit Form-30








List of Appendices -
download this instruction and all appendices in MSWord format (Word document, 562KB, download Word viewer for free)

Appendix A. Background Information on Silica

Appendix B. Industries with Potential Overexposure to Crystalline Silica

Appendix C. Guidelines for Air Sampling

Appendix D. Cyclone Leak Test Procedure

Appendix E. Conversion Factor for Silica PELs in Construction and Maritime

Appendix F. Employee Questionnaire

Appendix G. Medical Monitoring Recommendations for Employees Exposed to Crystalline Silica

Appendix H. CSHO Checklist for Conducting Silica-Related Inspections

Appendix I. References

Appendix J. Bibliography

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