Guide to Respirable Crystalline Silica

Risks, Prevention, and Workplace Safety

Crystalline Silica is a common mineral, typically found in sand, stone, and soil, and is most commonly used to make products like concrete, cement, bricks, artificial stone, glass, mortar, and many other different types of industrial materials.

Although the average person isn’t likely to come into contact with crystalline silica on a regular basis, workers who handle and use these types of materials are at a higher risk of being exposed.

When crystalline silica becomes respirable, it can have long-lasting, serious health risks, even in small concentrations. Understanding the risks and how to minimize exposure is the first step in keeping yourself safe from the dangers of respirable crystalline silica.

What is Respirable Crystalline Silica?

Crystalline silica commonly occurs in several forms, including quartz, cristobalite, and tridymite. Quartz is the most common form encountered in many occupational settings.

Respirable crystalline silica can be generated when materials containing crystalline silica are crushed, sawed, sanded, drilled, ground, or otherwise disturbed. These activities can create very fine airborne dust particles that are small enough to travel deep into the lungs when inhaled.

These dust particles are typically less than 10 micrometers (or 10 microns) or less; at least 100 times smaller than everyday sand you might find on the beach.

The primary health concern associated with respirable crystalline silica is the risk posed by inhalation. When these fine particles are breathed in, they can travel deep into the lungs and, with sufficient exposure, contribute to serious and potentially irreversible health effects.

How Respirable Crystalline Silica Penetrates the Lungs

When materials containing crystalline silica are aggressively disturbed (typically during construction and manufacturing processes), the silica fractures into microscopic, airborne particles.

Because these particles are so small, they can easily bypass the body’s natural respiratory defenses, such as nasal hairs and mucous membranes. Upon inhalation, these ultrafine particles travel deep into the lungs and can’t be cleared effectively by coughing, leading to symptoms including:

Coughing
Shortness of Breath
Chest Pain
Fatigue

If exposure to this dust happens over a long period of time, or if you experience a shorter period of very heavy exposure, it can put you at serious risk of developing silicosis.

What is Silicosis?

Silicosis is an incurable, irreversible, and sometimes fatal disease caused by exposure to silica dust. When this dust is inhaled, it can cause inflammation and scarring in the lungs, affecting your breathing and often leading to serious secondary health conditions like:

Chronic Obstructive Pulmonary Disease (COPD)
Pulmonary Hypertension
Tuberculosis (TB)
Autoimmune Diseases
Kidney Disease
Lung Cancer

Types of Silicosis

Silicosis symptoms aren’t always obvious right away, and often depend on how much silica dust you were exposed to and over what amount of time. The three main types of silicosis are:

Chronic Silicosis

As the most common form of silicosis, chronic silicosis results from long-term exposure to low levels of respirable crystalline silica, typically over a period of 10 or more years.

Accelerated Silicosis

Accelerated silicosis develops over a considerably shorter period of time, usually anywhere from 5 to 10 years after exposure to larger amounts of silica dust.

Acute Silicosis

Acute silicosis is the most severe form of silicosis, and comes on the fastest; typically occurring after even just a few months of exposure to high levels of respirable crystalline silica.

How Much Silica Dust is Harmful?

Many workers in industries frequently exposed to silica dust wonder how much exposure to silica dust is dangerous, and how much silica dust causes silicosis.

At the time of publication, OSHA’s current exposure limits for respirable crystalline silica are as follows:

Permissible Exposure Limit PEL: 50 μg/m³ as an 8-hour time-weighted average (TWA)
Action level: 25 μg/m³, which is the lower level at which monitoring and other requirements begin

The action level is used within OSHA’s silica standards to trigger certain exposure-assessments and other requirements, depending on the work being performed and the applicable OSHA standard.

Any exposure should be taken seriously, particularly if the exposure is heavy or long-term.

No amount of silica dust exposure is considered to be completely risk-free, but exercising caution and reducing your exposure can help reduce the likelihood of developing silicosis and other related conditions.

Understanding Silica Exposure: Skin Contact and Ingestion

While the respiratory hazards of crystalline silica are severe, the mineral itself is non-toxic in its natural state. Handling solid materials containing silica, such as stone, brick, or concrete, isn’t considered to pose a health risk through skin contact.

Similarly, ingesting crystalline silica does not carry the same risks as breathing it in. Silica is a naturally occurring mineral frequently found in groundwater sources and municipal water supplies. When silica is consumed in drinking water, it passes through the digestive tract without entering the respiratory system or accumulating in the lungs.

Reducing Occupational Exposure

According to OSHA, roughly 2.3 million people in the United States are exposed to silica at work.

When it comes to the risks of respirable crystalline silica exposure, there are several methods that can be used to help reduce your exposure to particulate matter.

Common, effective mitigation strategies include:

Wet Methods: Applying water directly to the blade or cutting surface to suppress dust before it becomes airborne.
Local Exhaust Ventilation: Using vacuum systems equipped with HEPA filters to capture dust at the point of generation.
Isolation: Keeping unprotected employees away from areas where silica dust is actively being generated.
Respiratory Protection: Supplying appropriately rated respirators for high-risk areas.

Respirable Crystalline Silica Analysis From EHS Laboratories

Environmental Hazards Services provides laboratory analysis for occupational respirable crystalline silica samples.

EHS Laboratories is accredited through the AIHA Laboratory Accreditation Programs, LLC for the analysis of respirable crystalline silica using NIOSH Method 7602.

For clients who already have an established sampling program, EHS can provide the laboratory analysis needed to help evaluate occupational exposure to respirable crystalline silica.

Learn more about EHS’ respirable crystalline silica testing services.

Have questions about submitting silica samples or laboratory testing requirements?

Contact EHS today to take the first step towards creating a healthier working environment.