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OSHA's National Emphasis Program for Crystalline Silica


On January 24, 2008, OSHA published a National Emphasis Program (NEP) to target worksites where employees are at risk for developing silicosis.  The directive, CPL-03-00-007, expands on a previous NEP for crystalline silica and has a goal of reducing or eliminating overexposures to crystalline silica.  The directive will increase inspections in targeted worksites, provide outreach information and compliance assistance to employers.

The NEP does not establish a new Permissible Exposure Limit (PEL) for crystalline silica but instead provides direction on how inspections are to be conducted and citations prepared.

OSHA compliance officers will target industries known to have overexposures to silica and conduct inspections.  OSHA may collect air samples to assess exposures and/or review existing monitoring records.  In addition to this, the following control or protection methods will be reviewed:

What is Crystalline Silica? 

Silica is used to describe the mineral compound silicon dioxide (SiO2).  It is often confused with silicone which is quite different.  Silicon dioxide exists in crystalline or amorphous forms and the crystalline form is much more hazardous.  Examples of amorphous forms of silica include silica gel, fused silica, precipitated silica and fumed silica.  Crystalline silica occurs primarily in three forms- quartz, cristobalite and tridymite.  The OSHA directive applies only to crystalline forms of silica.

Crystalline silica has long been known to cause lung disease known as silicosis.  Silicosis is a fibrotic lung disease.  Symptoms of exposure include cough and shortness of breath.  It can progress with symptoms worsening over time, even in the absence of further silica exposure.  Chronic silicosis occurs following long period of exposure  (20-40 years).  Accelerated silicosis is a form of chronic silicosis and can occur after 5-15 years of more intense exposures; the disease progresses more quickly than chronic silicosis.  Acute silicosis can occur as soon as a few weeks following massive, short term exposures.   Progression of the disease can lead to respiratory failure and death; it is an incurable disease.

The development of silicosis depends on a number of factors including the length of exposure, the amount of the exposure and the size of the dust particles.  Small particles, less than 10 microns in diameter, are the most hazardous because they can penetrate deep into the lung.  These particles are called "respirable" particles.

IARC (the International Agency for Research on Cancer) has classified crystalline silica as a carcinogen.  According to the OSHA Directive "... the IARC Working Group noted “that
carcinogenicity in humans was not detected in all industrial circumstances studied.” The
Working Group also stated: “Carcinogenicity may be dependent on inherent characteristics of the crystalline silica or on external factors affecting its biological activity or distribution of its polymorphs.”

Other studies have found associations between crystalline silica exposure and chronic obstructive pulmonary disease, immunological disorders, autoimmune diseases and renal disorders.

Where Can Crystalline Silica Exposure be Found?

Crystalline silica exposure can occur in many workplaces.  It should be noted that its presence is not always clearly identified on labels or Material Safety Data Sheets (MSDSs).  Synonyms for crystalline silica include alpha quartz, quartz, free silica and SiO2 (silicon dioxide).  Crystalline silica may also be present in other materials but may not specifically listed on labels or MSDSs.  These materials include flint, granite, slate, sandstone, mica, shale, clays, lake sand, beach sand and silica flour.

Processes that can be problematic include dry cutting or grinding on materials containing crystalline silica; bag dumping of crystalline silica containing materials; abrasive blasting when sand is used; housekeeping tasks that disperses silica containing dusts into the air; and the removal and replacement of refractory materials.  

Exposures can be found in the following operations:

Air Sampling

Sampling for crystalline silica is confusing and inadequate exposure assessments are common.  There are several different exposure limits and they are not expressed in the same terms which has lead to improper interpretations of the data. 

In the Directive, OSHA provides guidelines on how to conduct air sampling to assess crystalline silica exposures.  For comparison with the OSHA PEL for crystalline silica, air samples must be collected with a Dorr-Oliver cyclone that will separate the dust into the repairable and on-respirable fractions; the amount of crystalline silica in the respirable dust is compared directly or indirectly with the PEL.   

How Can Industrial Hygiene Sciences, LLC Help You ?

Industrial Hygiene Sciences, LLC has conducted hundreds of crystalline silica surveys, especially in the foundry industry, and has the experience you need to identify and manage your exposures to crystalline silica.  Industrial Hygiene Sciences, LLC can assist you by reviewing your past monitoring records, establishing a sampling strategy, collecting air samples, interpreting the results, selecting protective equipment and indentifying control options. 

OSHA's Hexavalent Chromium Standard (1910.1026 & 1926.1126)

Overview of the Standard

On February 28, 2006, OSHA published their new standard on hexavalent chromium.  The new standard lowered the PEL (Permissible Exposure Limit) to 0.005 mg/m3 (5 µg/m3) as a TWA (time weighted average) and established an Action Limit of 0.0025 mg/m3 (2.5 µg/m3) as a TWA.  The standard requires employers to:

There are several exemptions to the standard including

What is Hexavalent Chromium?

Chromium is a common metal.  It exists in a number of different valence states and the hexavalent form has been associated with significant adverse health effects including cancer, damage to the nasal tissues, asthma and allergic skin reactions. In solid metal, the chromium is in a different valence state so handling materials made of stainless steel for example will not create exposures to hexavalent chromium.  If that material is heated to high temperatures, the chromium can convert into the hexavalent state and result in potential exposure to workers. 

Hexavalent chromium also exists in several different forms (i.e. water soluble and water insoluble).  The Hexavalent Chromium Standards only covers exposures to the hexavalent form of chromium but it covers any chromium species with this valence state.

Where Can Exposures be Found? 

Chromium is used in the production of stainless steel and other alloys, metal plating and other metal surface treatments and pigments.  Exposures can occur during processes that heat alloys to high temperatures (i.e. welding, cutting, torching, arc gouging, or melting and pouring of metal); removal of surface coatings during demolition, repair or salvaging operations; painting; and the formulation of compounds that contain hexavalent chromium.  Significant exposure can occur when performing such tasks in confined spaces such as tanks.  Here is a list of processes or industries where exposures can be found:

Employers with 20 or more employees had until November 27, 2006 to comply with the regulation with the exception of implementation of engineering controls.  Employers with 19 or fewer employees had until May 30, 2007 to comply with the standard although implementation of engineering controls where exposures exceed the PEL was delayed for all employers, regardless of size.  All employers with exposures that exceed the PEL must attempt to reduce exposures through engineering controls or work practice changes by May 31, 2010.

Air Sampling

If you think you may have exposures that could exceed 0.5 µg/m3 as a TWA, then air sampling can establish your baseline exposures and what, if any further actions need to be taken.  Many, but not all, of the actions that may be required are triggered by the employee's airborne exposures.

Many employers have had monitoring in the past but you should carefully look at your exposure records to determine if the samples were collected and analyzed specifically for hexavalent chromium.  In many cases samples measured total chromium, especially in situations where other metals were present and one sample was collected to analyze many metals from this single sample.  OSHA ID-215 is the most widely used method to analyze samples for hexavalent chromium.


In January, 2008, OSHA issued its Compliance Directive for Hexavalent Chromium that provides information on how OSHA will enforce the standards.  The OSHA Hexavalent Chromium webpages also contains links to standard interpretations, the text of the standards, a compliance guide and information on health effects of hexavalent chromium.

How Can Industrial Hygiene Sciences, LLC Help You Meet the OSHA Requirements?

If you are affected by this standard, Industrial Hygiene Sciences, LLC can review your past monitoring records, establish a sampling strategy, collect baseline and periodic air samples, and assist you with complying with the OSHA standards.  Industrial Hygiene Sciences, LLC has conducted many hexavalent chromium surveys in the foundry, metal fabrication, electroplating, anodizing, painting industries and has the experience you need to identify and manage your exposures to hexavalent chromium.  Please contact IHS for further assistance.

NIOSH Publications on Indoor Firing Ranges

Indoor firing ranges are used for law enforcement training and recreation.  NIOSH estimates that there are 16,000-18,000 firing ranges across the United States.  Employees working in the ranges, coaches and law enforcement officials using the range can be exposed to excessive amounts of lead and noise. 

A new NIOSH document, “Reducing Exposure to Lead and Noise at Indoor Firing Ranges” is a short summary about these exposures.  It presents the results of two case studies showing significant exposures to lead and noise and recommendations for reducing exposures and protecting users.  NIOSH has a webpage dedicated to exposures at Indoor Firing Ranges where you can access many documents about lead and noise exposures and protective measures. 

If you operate an indoor firing range and need assistance with assessing exposures, contact Industrial Hygiene Sciences, LLC.

How to Put on a Disposable Respirator

NIOSH has recently published a one page description of how to properly put on a disposable, filtering facepiece respirator.  It is illustrated with photographs and shows how to put on (don in OSHA terminology) the respirator, inspect it for leaks and how to take it off (doff).  The page is also available in Spanish. 

There is a widespread misconception that disposable “dust masks” are not respirators.  While some are not, a “dust mask” can be a respirator and carry a NIOSH certification.  In the OSHA Respiratory Protection Standard (1910.134), dust masks are called “filtering facepiece respirators”.  If you require employees to wear such a respirator, you must provide medical evaluations, fit testing and training and develop a written program to comply with the OSHA Respiratory Protection Standard.  If these respirators are used on a voluntary basis (e.g. they are made available for employees to use but are not required either because of an overexposure tor company policy), then Appendix D of the standard must be shared with the employees.

If you need assistance with your respiratory protection program, contact Industrial Hygiene Sciences, LLC! 

Updated April, 2010