Sand Blasting Silica: The Ultimate Guide (2024)

Sandblasting with silica sand is a dangerous process that can cause serious or even fatal respiratory disease. When used in abrasive blasting, silica sand fractures into fine particles and becomes airborne. These particles are so small that even proper sandblasting respirators may not be sufficient to prevent inhalation. When inhaled, crystalline silica causes silicosis, a fibrotic condition of the lung where fibrous nodules and scarring develop around the trapped silica particles. This makes it difficult to breathe and leads to a range of symptoms including cough, weight loss, fatigue, and shortness of breath. In some cases, silicosis can lead to respiratory failure and death.

Due to the health risks associated with silica sandblasting, it is forbidden in many countries and highly restricted in others. To protect workers, employers must implement engineering or administrative controls to reduce employee exposure to silica dust. This includes the use of ventilation, blast rooms, and respirators.

Silicosis and its health implications

Silicosis is a long-term, irreversible, and progressive lung disease caused by inhaling crystalline silica dust. It is characterised by pulmonary fibrosis, leading to restrictive lung disease. Silicosis is incurable and can be fatal. Even after exposure to silica dust has ceased, pulmonary inflammation and damage will progress.

There are three types of silicosis, depending on the level of exposure to crystalline silica:

• Chronic silicosis: This usually occurs after 10 or more years of exposure to crystalline silica at relatively low concentrations. It can also affect the upper lungs and cause extensive scarring.
• Accelerated silicosis: This occurs within five to ten years of high-level exposure to silica dust.
• Acute silicosis: This occurs within a few weeks to five years of initial exposure to high concentrations of silica dust. Acute silicosis can cause fluid in the lungs, leading to low oxygen levels, cough, weight loss, and chest pain.

Silicosis causes inflammation, fibrosis (scarring), and coughing. As the disease progresses, it can lead to respiratory failure and death. Silicosis also makes individuals more susceptible to other serious respiratory diseases and conditions, including tuberculosis, chronic bronchitis, chronic obstructive pulmonary disease (COPD), lung cancer, pulmonary hypertension, and autoimmune diseases such as scleroderma and rheumatoid arthritis.

The use of silica sand in sandblasting is banned in many countries due to the health risks associated with inhaling silica dust. However, silica sand is sometimes still used in sandblasting, despite the dangers and health implications. To prevent silicosis in workplaces, it is crucial to use protective equipment, isolate processes that produce silica dust, use ventilation and blasting cabinets, and conduct regular inspections and employee training.

The banning of silica sand in many countries

Silica sand, also known as quartz sand, is made up of silica and oxygen, specifically silicon dioxide (SiO2). It is the primary raw material used to create concrete, asphalt, glass, silicon chips, and more.

While silica sand is a crucial resource, it is also dangerous. When blasted with silica sand, each grain of sand is smashed into extremely fine dust particles with sharp edges. These particles are too small to see, but they can penetrate deep into the lungs when inhaled. Chronic inhalation of respirable crystalline silica dust can lead to severe lung disease, including silicosis and lung cancer.

Due to the health risks associated with silica sand, many countries have banned its use. The United Kingdom banned blasting with silica sand in 1949, and all European countries followed suit in 1966. In the 1990s, all Australian states banned the use of silica sand as an abrasive, with Victoria being the last state to do so in 2002.

Despite these bans, silica sand is still commonly used in other parts of the world, particularly in low-labour-cost countries such as Indonesia, Cambodia, India, Pakistan, and Bangladesh. However, there have been growing concerns and efforts to ban the use of silica sand in these countries as well. For example, in 2013, a protest was held in Milan against fashion houses that had not signed an anti-sandblasting petition. Additionally, organisations like the Clean Clothes Campaign have been fighting to ban sandblasting in the production of jeans worldwide.

Substitutes for silica sand in abrasive blasting

The use of silica sand for abrasive blasting has been prohibited in most countries since it often leads to a serious or fatal respiratory disease called silicosis. This is caused by the inhalation of respirable crystalline silica dust, which scars and hardens the lungs.

There are several alternative materials that can be used for abrasive blasting, including:

• Metal slag
• Steel grit
• Specular haematite
• Copper slag
• Nickel slag
• Crushed glass
• Glass beads
• Olivine
• Garnet
• Coal slag
• Baking soda
• Dry ice
• Walnut shell
• Corn cob meal
• Calcined aluminum oxide
• Synthetic olivine
• Magnesium oxide
• Aluminum oxide
• Pumice
• Sawdust
• Corundum
• Glass beads
• Walnut shells
• Plastic

These materials vary in terms of hardness, shape, friability, and density, which makes them suitable for different applications. For example, baking soda is one of the softest and most friable media, making it non-destructive to most materials, while materials like calcined aluminum oxide are very aggressive and suitable for removing paint and rust from metal.

It is important to note that some of these alternative materials may also pose health and safety risks, so proper assessment and control measures should be implemented by employers.

Respiratory protection practices

Sandblasting is a dangerous job that can lead to serious respiratory diseases, including silicosis, lung cancer, chronic obstructive pulmonary disease (COPD), and kidney disease. The National Institute for Occupational Safety and Health (NIOSH) and the Occupational Safety and Health Administration (OSHA) have outlined various respiratory protection practices to prevent these diseases.

NIOSH recommends the following respiratory protection practices:

• Prohibit silica sand or other substances containing more than 1% crystalline silica as an abrasive blasting material and substitute less hazardous materials.
• Conduct air monitoring to measure worker exposure to silica dust.
• Use containment methods such as blast-cleaning machines and cabinets to control the hazard and protect adjacent workers from exposure.
• Practise good personal hygiene, such as washing hands and faces before eating, drinking, or smoking, and wearing disposable or washable protective clothing.
• Use respiratory protection when source controls cannot keep silica exposures below the NIOSH REL.
• Provide periodic medical examinations for all workers who may be exposed to crystalline silica.
• Post signs to warn workers about the hazard and inform them about required protective equipment.
• Provide workers with training on health effects, work practices, and protective equipment for crystalline silica.

OSHA requires abrasive-blasting respirators to be worn by all operators when using silica sand in manual blasting operations where the nozzle and blast are not physically separated from the operator in an exhaust-ventilated enclosure. When abrasive-blasting respirators are temporarily unavailable, dust-filter respirators may be used as interim protection. However, it is important to ensure that the airborne concentration of crystalline silica does not exceed the protection factor of the respirator. Additionally, if the dust-filter respirator does not protect the operator's eyes and face, supplementary equipment must be provided.

To meet the air purity requirements for abrasive blasting, two primary options are available: a supplied air respirator with an oil-free compressor or a supplied air respirator with a compressed air system. When using a supplied air respirator with a compressed air system, it is crucial to ensure that the air meets Grade D breathing air standards and has less than 10 ppm carbon monoxide.

Overall, it is essential to prioritize respiratory protection practices to safeguard workers' health when performing sandblasting operations.

The dangers of silica sand

Silica sand is one of the most common hazards in workplaces, especially in the construction, oil and gas, manufacturing, and agriculture industries. It is a mineral compound, silicon dioxide (SiO2), found in two forms: crystalline or non-crystalline (amorphous). Sand and quartz are common examples of crystalline silica. Crystalline silica is a common mineral found in soil, sand, granite, concrete, rock, and many other materials.

Silica dust is released when materials containing silica are disturbed, generating small particles that can enter the lungs. This includes activities such as blasting, cutting, chipping, drilling, grinding, crushing, loading, hauling, or even dry sweeping. These small particles of crystalline silica are hazardous when inhaled, causing a range of serious health issues.

The dangers of silica dust are well documented, with long-term exposure leading to debilitating and life-threatening diseases. One of the most severe effects of silica exposure is silicosis, a disabling and irreversible lung disease. Silicosis occurs when silica dust enters the lungs, causing the formation of scar tissue, reducing the lungs' ability to take in oxygen. There is no cure for silicosis, and severe cases can lead to respiratory failure and death.

In addition to silicosis, exposure to silica dust has been linked to lung cancer, chronic obstructive pulmonary disease (COPD), kidney disease, and other autoimmune disorders. The risk of these diseases increases with long-term or repeated high-level exposure to silica dust. It is estimated that hundreds of people develop lung cancer each year due to past exposure to silica dust at work.

The Occupational Safety and Health Administration (OSHA) has recognized the dangers of silica and tightened restrictions on the amount of silica workers can be exposed to. Employers are responsible for understanding the risks and taking steps to reduce silica exposure, such as using different materials or implementing engineering controls to reduce dust.

Protective measures, such as respiratory protective equipment (RPE), are also crucial in reducing the risk of silica dust inhalation. However, RPE should be used in combination with other controls as it cannot completely prevent silica dust inhalation.

Frequently asked questions