Silicosis is a serious chronic lung condition caused by prolonged inhalation of fine particles of free crystalline silica (SiO₂). This exposure typically occurs in occupational environments where materials containing silica – such as sand, quartz, granite, or sandstone – are handled. The disease is irreversible and continues to progress even after exposure to the harmful substance has ceased.

Silicosis: A Pulmonary Disease Caused by Exposure to Free Crystalline Silica (SiO₂)

Background and Prevalence

Blasting emerged as a result of observing the natural erosion process of the rocks, which become more and more smooth over long periods of time under the erosive action of waters and sand carried by the wind. By blasting, achieving the same erosion effect is aimed, but in a short period of time, using mechanical acceleration of the abrasive particles. In 1870, Benjamin Tilghman designed the first blasting machine to remove rust and paint from surfaces, and then, in 1904, Thomas Pangborn improved the concept using a mix of compressed air and yellow sand to clean metallic surfaces. It was the beginning of a long period when yellow sand was largely used for blasting operations.

Over time, it was observed that using yellow sand for blasting had caused a great number of lung diseases and deaths among blasting operators as a result of silicosis illness. Silicosis is a lethal disease, with no treatment, that is caused by the inhalation of free silica crystals, which are found in the dust released during the blasting operations with yellow sand. Other names of free silica crystals are: crystalline silica, free silica.

Silicosis is one of the oldest known occupational diseases, with references dating back to the time of Hippocrates. Over the centuries, it has been recognized as a significant health concern in industries involving the processing of materials that contain free crystalline silica.

In Romania, silicosis ranks second among occupational diseases, following musculoskeletal disorders caused by overuse. It accounts for approximately 25% of all officially reported occupational illnesses in recent years.

Currently, due to the high number of silicosis diseases, the Netherlands and other European countries have forbidden the use of blasting agents containing more than 0.1% free silica. Yellow sand contains about 90% free silica particles, therefore it is extremely dangerous for operators’ health. Due to their high friability during blasting operations, the yellow sand particles break down into very fine particles of free silica, between 2 and 10 microns (µ). These particles are then inhaled and embedded in the lung alveolar cells, with no possibility to remove them by any type of treatment. As a defensive barrier against foreign bodies into the organism, the free silica particles embedded into the lungs are covered by tissue, leading to the formation of multiple nodules into the lungs, which generate respiratory failure, multiple complications, cancer and death.

Mechanism of Action and Symptoms

Silicosis is a form of collagenous pneumoconiosis, characterized by nodular pulmonary fibrosis. Continuous inhalation of inorganic dusts with high concentrations of free crystalline silica triggers a severe fibrogenic reaction in the pulmonary interstitium. This accumulation gradually impairs lung function, leading to a progressive decrease in respiratory capacity and the development of severe symptoms such as persistent coughing, shortness of breath, and—at advanced stages—respiratory failure.

Silicosis can manifest in several forms:

• Acute silicosis, resulting from extremely intense exposure, with rapid onset and severe respiratory impairment.
• Subacute silicosis, developing over several years of continuous exposure to silica dust.
• Chronic silicosis, the most common form, evolving slowly with progressively worsening symptoms.

Using yellow sand in blasting operations is extremely dangerous even when the operators wear protective blasting equipment. During windless atmosphere, a 2 microns particle of free silica drops only 1 meter in 24 hours, forming an invisible cloud of dust of free silica particles, surrounding the work site. After finishing blasting work or during time breaks, when the operator remove its protective helmet, a large amount of free silica particles from the invisible dust cloud are inhaled and other particles are deposited into the interior of the helmet, being later inhaled, when the operator puts the helmet back. Further, it was observed that the invisible dust cloud of free silica particles affects not only the blasting operators, but also the staff operating in the surrounding area, like office staff, cleaning staff, security and others.

Once installed, the disease does not heal and is continuously aggravating, leading to death. At international level, it is suggested that even one exposure to the free silica particles can lead to silicosis. Considering the danger of exposure to free silica particles, along with the countries that had expressly forbidden the use of yellow sand in blasting operations, multiple international bodies that normalize and standardize risk areas are taking an active part in fighting against using yellow sand in blasting operations, by conducting awareness campaigns of the hazards involved, issuing standards, norms and safety procedures, and by certifying those companies that comply with these standards, norms and procedures. Therefore, using yellow sand is not recommended by FROSIO – The Norwegian Professional Council for Education and Certification of Inspectors of Surface Treatment, NACE – National Association of Corrosion Engineers, SSPC – The Society for Protective Coatings.

Industries and Occupations at Risk of Free Crystalline Silica Exposure

Occupational exposure to free crystalline silica is predominant in industries working with rock, sand, or other abrasive materials. Key sectors and high-risk professions include:

1. Mining and Quarrying Industry

• Mining: Workers are regularly exposed to silica dust generated during the extraction of rock and ores.
• Silica-rich quarries (quartz, sandstone, granite, quartzite): The extraction process generates respirable silica particles, increasing silicosis risk.

2. Construction Industry

• Granite cutting and shaping: These activities release high volumes of dust, posing a major risk to workers.
• Road and building construction: Excavation, drilling, and demolition of concrete and stone structures expose workers to silica particles.
• Tunnel, railway, and hydropower construction: Excavation dust is often rich in free crystalline silica.

3. Abrasive Materials and Glass Manufacturing

• Production and use of abrasives: Involves the manufacturing of grinding wheels, abrasive discs, and equipment for metal finishing.
• Glass manufacturing (preparation, blasting): The glass processing workflow releases fine silica-containing dust.

4. Abrasive Blasting

• This surface-cleaning technique generates significant amounts of respirable crystalline silica particles.

5. Metallurgy and Metal Processing Industry

• Blasters, cleaners, grinders, polishers: These processes release hazardous dust during metal cleaning and finishing.
• Construction, repair, demolition of industrial furnaces: Refractory brick masons are exposed to silica dust from refractory materials.

6. Stone and Ceramics Processing Industry

• Glass, porcelain, and ceramic manufacturing: Cutting and finishing operations involve high-risk exposure to fine dust.
• Paints and plastics industry: The production of silicon-based additives involves handling of hazardous materials.

7. Artisanal and Hobby Industries

• Sculptors and glassblowers are exposed to silica during artistic material processing.

8. Other Exposed Sectors

• Geological surveying, flotation stations: Involves frequent contact with silica-rich ores.
• Stone restoration and processing industry: Stone cutters and carvers are exposed due to the nature of their work.

Companies should stop using yellow sand in blasting operations, considering the illness hazard of operators’ exposure to free silica particles, the compensations that should pay to their employees in case of claims of occupational diseases, and considering the fact that, being so friable, yellow sand is not an efficient blasting material, unlike other blasting agents, such are, for example: red garnet, angular steel grit, steel shots, stainless steel grit, stainless steel cut wire shots, white fused aluminium oxide, brown fused aluminium oxide, glass beads, blasting grit (nickel slag) and copper slag.

Red garnet is a highly efficient, ecologic and non-toxic blasting media (free silica content < 0,1%). Due to its superior hardness of 8 on Mohs scale, red garnet is very efficient in blasting operations. Also, the material is chemically stable, it does not impregnate the cleaned surface and can be successfully used for surfaces where ferrous contamination is not tolerated, like: stainless steel, aluminium, copper. Further, red garnet is a reusable material, and can be used both indoor and outdoor. GritSablare is national leader on providing red garnet and complete solution for blasting and water jet cutting materials.