Don't Get Sandblasted - How to Protect Yourself from Silica Dust on the Job
Table of Contents
Introduction
Silica sand, also known as quartz sand, is one of the most common minerals on earth and is an important raw material for many industries. Silica sand contains high levels of silicon dioxide (SiO2) and is found in quarries and mines around the world.
Some of the major industries that use silica sand include:
– Glass manufacturing – Silica sand is the primary component of all types of standard and specialty glass. It provides the essential SiO2 base and its chemical purity is the primary determinant of color, clarity, and strength.
– Metal casting and foundry – Silica sand is used to make molds and cores for metal foundries. The high heat resistance of quartz makes it ideal for foundries to cast both ferrous and non-ferrous metals.
– Oil and gas recovery – Also known as frac sand, silica sand plays a crucial role in the hydraulic fracturing process to extract oil and natural gas from shale deposits. The hardness and shape of the sand grains allow oil and gas to flow out of shale cracks.
– Construction – Silica sand is a key ingredient in construction materials like concrete, mortars, plasters, asphalt shingles, and cement. It provides bulk, strength, and other properties to construction products.
– Ceramics and refractories – Silica sand is used to make products such as glass, pottery, tiles, and other ceramics. It is a key ingredient in clays and other refractory materials.
– Paints, coatings, and polymers – Silica sand is used as a filler or extender in paints, coatings, plastics, resins, and other polymeric products. It enhances properties like hardness, color consistency, and corrosion resistance.
– Abrasives – The hardness of silica sand makes it suitable for use as an abrasive in products like sandpaper, sandblasting materials, grinding wheels, and cutting tools. It is also used in products like toothpaste.
– Filtration – Silica sand is frequently used as a filter media at both industrial and consumer scales. It is highly porous and does not react with substances filtered through it.
– Agriculture and landscaping – Silica sand is used for bunkers and greens on golf courses, for horse arenas and turf, and as filler in landscaping and paving products.
– Other uses – Silica sand also has some applications in food production, water filtration, sports fields, and even hydraulic fracturing. The diversity of uses stems from its chemical and physical properties.
While silica sand enables countless products and industrial processes, it poses potential health hazards in work environments. Inhaling fine silica dust can lead to silicosis and other respiratory diseases which we will cover in more detail later. Thus, it is vital for employers to implement safety measures and best practices when working with silica sand.
What is Silica Sand?
Silica sand, also known as quartz sand, is composed almost entirely of silicon dioxide (SiO2). It’s made up of crushed quartz crystals and is characterized by its high silica content and abrasive properties.
Silica sand has a number of unique physical and chemical properties that make it useful for various industrial applications:
– Composition – It is made up of 99%+ quartz particles. Natural silica sands contain other impurities like clay, iron oxide, and organic matter in smaller quantities.
– Hardness – Silica particles have a hardness of 7 on the Mohs scale, making them ideal for abrasive blasting and other applications where durability is required.
– Chemical stability – The SiO2 composition makes silica sand chemically stable and resistant to attack from acids and alkalis. This allows it to be used in demanding environments.
– Thermal stability – Silica sand can withstand very high temperatures up to 1700°C making it suitable for use in foundries, glassmaking, and other high temperature processes.
– Grain shape – Silica sand particles are typically angular to sub-angular in shape. This interlocking structure provides strength when used in construction materials.
– Color – The most common color of silica sand is white. But it can range from yellowish to greyish depending on mineral impurities.
– Permeability – Silica sand has low permeability, which makes it useful for hydraulic fracturing applications.
The combination of chemical purity, hardness, thermal stability, and grain size make silica sand a versatile industrial mineral. It is a key ingredient in concretes, mortars, ceramics, filtration systems, abrasives, and more. Understanding its properties helps explain its widespread use across numerous industries.
Industries that Use Silica Sand
Silica sand is a key ingredient in many industries and products we use every day. Here are some of the most common industrial applications:
1. Fracking
Fracking, or hydraulic fracturing, is a process used to extract oil and natural gas from shale rock. Silica sand is used as a proppant to hold open the underground fractures so that oil and gas can be extracted. The silica sand keeps the fractures open, allowing fossil fuels to flow into the wellbore after fracking fluid is pumped out.
2. Foundries
Foundries use silica sand as the main molding material for metal casting. The sand is molded into the shape of the desired metal parts, and liquid metal is poured into the mold cavity. The silica sand provides thermal insulation and withstands the high temperatures of molten metal. It also provides dimensional accuracy and fine surface finishes to casted metal parts.
3. Construction
In construction, silica sand is a key ingredient in concrete, asphalt, and mortar mixes. It provides bulk, strength, and durability to concrete and cement products. Silica sand is also used for sandblasting applications in the construction industry to provide smooth finishes to stone, metal, and other surfaces.
4. Glass Manufacturing
Silica sand is the primary component of all types of standard and specialty glass. It provides the essential SiO2 component of glass formulation and its chemical purity is critical to color, clarity, and strength of glass products. Silica sand is used in glass manufacturing industries such as containers, flat glass, specialty glass, and fiberglass.
Potential Health Hazards
Working with silica sand can lead to several serious health conditions if proper safety precautions are not followed. The most common risks include:
1. Silicosis
Silicosis is a lung disease caused by inhaling respirable crystalline silica dust. It leads to inflammation and scarring of lung tissue, which reduces the lungs’ ability to take in oxygen. Symptoms include shortness of breath, cough, and chest tightness. There are three types of silicosis:
– Chronic silicosis – Develops after 10 or more years of moderate to low exposures to respirable crystalline silica. This is the most common type.
– Accelerated silicosis – Results from higher exposures and develops 5-10 years after first exposure.
– Acute silicosis – Occurs where exposures are the highest and can cause symptoms to develop within a few weeks to 4-5 years after initial exposure.
2. Lung Cancer
Multiple studies have shown that workers exposed to respirable crystalline silica dust are at increased risk of developing lung cancer. The risk is higher for those who already have silicosis. The International Agency for Research on Cancer (IARC) has classified inhaled crystalline silica as a human carcinogen.
3. Kidney Disease
There is evidence that exposure to respirable crystalline silica can lead to chronic kidney disease and end-stage renal disease. Several studies have found higher rates of kidney dysfunction in occupations with frequent silica exposure. The mechanism linking silica exposure to kidney damage is not fully understood but may be related to inflammation.
OSHA Regulations
The Occupational Safety and Health Administration (OSHA) has regulations in place to protect workers from exposure to respirable crystalline silica. The permissible exposure limit (PEL) is 50 micrograms per cubic meter of air (50 μg/m3), averaged over an 8-hour workday.
To comply with OSHA regulations, employers must:
– Measure worker exposure levels to ensure they are below the PEL
– Provide proper respiratory protection when exposure exceeds the PEL
– Use engineering and work practice controls to limit worker exposure
– Provide training to workers about silica hazards
– Offer medical exams to highly exposed workers
Engineering controls like wet cutting methods and local exhaust ventilation help reduce silica dust at the source. Proper housekeeping, such as using HEPA vacuums to clean work areas, also decreases overall exposure.
For tasks that generate extremely high silica levels, supplied air respirators may be required. Other permissible respiratory protection includes N95 filtering facepiece respirators and elastomeric half-mask or full facepiece air purifying respirators equipped with N100, R100, or P100 filters. Employers must have a written respiratory protection program when respirators are used.
OSHA has strict requirements regarding silica exposure to protect worker health and safety. Following the exposure limits, using proper controls, and providing training are key aspects of compliance.
Engineering Controls
Engineering controls aim to isolate or remove silica dust and silica particles from work processes and the air that workers breathe. This can be achieved through substitution, isolation, or ventilation.
a. **Substitution**
involves replacing hazardous materials with less hazardous alternatives. For example, substituting amorphous silica for crystalline silica, which is less toxic. Substituting blasting with mechanical chipping or road milling with asphalt planers also reduces silica exposures.
b. **Isolation**
separates the hazard from the worker by enclosing or isolating the process. Examples include isolating blasting and other high dust operations in containment structures or booths, and using remote controls to operate machinery from a separate control room.
c. **Ventilation**
removes and controls dust at the source before it gets into the air. This includes using local exhaust ventilation systems, dust collection systems, and vacuum dust cleaning methods. General ventilation can also help dilute dust levels. Wet drilling and wet sweeping are other effective dust control methods.
Proper maintenance of dust control systems is crucial. Isolation controls should be inspected regularly for damage. Ventilation systems require regular cleaning, filter changes, airflow monitoring, and overall maintenance for optimal effectiveness.
Administrative Controls
Administrative controls are policies and procedures that employers can implement to limit workers’ exposure to silica dust. These controls focus on changing how work is done, rather than relying solely on personal protective equipment. Key administrative controls for silica exposure include:
1. Training
A comprehensive training program is essential for ensuring workers understand the hazards of silica exposure and how to protect themselves. Training should cover:
– Health effects of silica exposure
– Operations that could result in exposure
– Engineering controls being used to limit exposure
– Proper use of respiratory protection
– Purpose and limitations of medical surveillance
Training should be provided initially and repeated periodically. Using classroom instruction, videos, hands-on demonstrations, and other engaging methods will help the training stick.
2. Job Rotation
Rotating workers across different tasks can limit their cumulative exposure to silica. Job rotation gives lungs a chance to clear some silica dust while working in environments with lower concentrations.
Care must be taken to ensure no single worker still gets excessive exposure. Job rotation may need to be coupled with adjustments to total work hours in high exposure tasks.
3. Housekeeping
Good housekeeping practices reduce dust levels in work areas. Floors, work surfaces and equipment should be cleaned frequently using vacuums with HEPA filters or wet sweeping methods. Compressed air should never be used for cleaning, as this can resuspend settled dust.
Prompt disposal of waste materials containing silica is also important. Allowing dust to accumulate on surfaces simply leads to future exposure. Maintaining clean worksites through regular housekeeping protects all workers.
Personal Protective Equipment
Personal protective equipment (PPE) is essential for protecting workers from exposure to respirable crystalline silica. Key types of PPE include:
1. Respirators
Using the proper type of respirator is critical when working in environments with airborne silica. The right respirator depends on the estimated silica exposure levels. For lower exposures, a disposable N95 filtering facepiece respirator may suffice. Higher exposures require a half or full facepiece respirator with N100, R100, or P100 filters. Powered air purifying respirators (PAPRs) are an option that provides increased comfort and ease of use. Proper fit testing and user seal checks should be conducted. Respirators must be worn according to a comprehensive respiratory protection program meeting OSHA requirements.
2. Protective Clothing
Clothing is needed to prevent skin contact with silica dust. Options include coveralls, tyvek suits, and disposable clothing that does not get reused away from the workplace. Sleeves should be tight at the wrists and pant legs worn over boots. Separate work clothes should be donned at the worksite and laundered by the employer. Work clothing should not be taken home where it could expose others. Sturdy leather or rubber gloves can also help protect hands from abrasive silica. Protective clothing needs to be kept as clean as possible to avoid silica buildup near workers’ breathing zones.
Medical Surveillance
Workers exposed to silica dust should undergo regular medical surveillance exams to monitor their health and detect any potential issues early. This typically involves the following:
– Baseline exam – An initial medical exam when starting a job involving silica exposure to determine fitness for duty and establish a baseline for future exams. This may include chest X-rays, pulmonary function testing, and assessment of any respiratory symptoms.
– Periodic exams – Regular medical exams recommended at least every 3 years, or more frequently for higher exposures. These monitor for signs of lung disease and track changes from the baseline exam. Exams may include chest X-rays, pulmonary function testing, and evaluation of respiratory symptoms.
– Exit exam – A medical exam when leaving a position involving silica exposure to document health status. This provides comparison to the baseline and periodic exams.
– Recordkeeping – Medical records, exam results, exposure measurements, and other relevant data should be maintained by the employer throughout employment plus 30 years.
The goal of medical surveillance is early identification of any silica-related health effects. This allows workers to make informed decisions about their health and employers to take action to prevent further exposure and disease progression. Regular health screening and monitoring is a vital component of protecting workers exposed to silica.
Creating a Safety Culture
A strong safety culture is crucial for protecting workers in industries that use silica sand. This starts with leadership and accountability. Management must demonstrate a commitment to safety, set policies that prioritize worker health, and dedicate resources for proper engineering controls, administrative controls, and PPE.
There also needs to be clear communication about the hazards of silica exposure and transparency around safety incidents. Management should foster open channels where workers feel comfortable raising concerns without fear of retaliation. Regular safety meetings, anonymous reporting mechanisms, and feedback surveys are examples of good communication practices.
Most importantly, safety must be recognized as everyone’s responsibility. There cannot be double standards for management versus frontline workers. All employees should receive extensive training on working safely with silica and upholding safety protocols. Peer accountability helps reinforce a culture where unsafe behaviors are not tolerated.
By making occupational health a shared value, companies can strive for zero incidents related to silica dust. But this requires buy-in at all levels and a collective commitment to proactively identifying and mitigating risks. A strong safety culture ultimately empowers everyone to look out for themselves and each other.
