Silicosis in the Construction Industry

Silicosis, a progressive fibrotic lung disease, is caused by the inhalation of respirable crystalline silica particles (RCS) (Deslauriers & Redlich, 2018).  Silica (SiO2) is a naturally occurring mineral found in rocks, sand, and soil in the forms of Quartz, Tridymite, and Cristobal (Baron et al., 2002; Deslauriers & Redlich, 2018).

Silicosis primarily affects workers in industries such as construction and mining, where silica dust exposure is prevalent (Kowalewski, 2022; Deslauriers & Redlich, 2018).

There are three forms of silicosis: acute, accelerated, and chronic (WHSQ, 2022). Acute silicosis occurs due to short term exposure of high levels of RCS. Accelerated silicosis

results from high-level RCS exposures over periods of between 1 to 10 years. Chronic silicosis is most common form and results from long term exposure (>10 years) to lower levels of RCS. Chronic silicosis can cause damage to the lungs and lead to other respiratory diseases, such as COPD, tuberculosis and lung cancer (WHSQ, 2022).

Respirable size particles (<10 µm) of crystalline silica dust retained in the lungs contribute to the primary pathogenesis of silica-related lung diseases (Kowalewski, 2022).

Although silicosis has long been recognized as an occupational lung disease, it remains commonplace in a range of industries, particularly construction (Wagner, 1998). However, there is a clear lack of awareness and limited attention to previous occupational and environmental exposures (Deslauriers & Redlich, 2018).


Respirable crystalline silica (RCS) particles are defined by OSHA as particles with a diameter of 10 µm or less, with the most hazardous particles being 4 µm or less in diameter due to their 50% deposition efficiency (Baron et al., 2002; Nicol et al., 2015; Nij & Hederik, 2005). Particles of this size are dangerous as they bypass mucociliary defence mechanisms and reach the distal portion of the lungs. When inhaled RCS particles can become trapped in the lungs, causing scarring, inflammation, nodules, impaired lung function, and increase the risk of lung cancer and tuberculosis (Nicol et al., 2015).

Silicosis involves a cycle of phagocytosis and particle release, resulting in epithelial damage, reduced gas exchange, and lung remodelling. Lung damage occurs in five main phases: direct cytotoxicity, generation of reactive species, production of cytokines and chemokines, fibrosis, and cell death through apoptosis (Kowalewski, 2022).

The mechanism that Silica causes lung damage with relates to reactive oxygen species (ROS) and reactive nitrogen species (RNS). These molecules are part of the bodies defence system against microbial pathogens; however, they often target other agents such as particulates on accident. When RCS is inhaled, alveolar macrophages are released from the body that cause respiratory bursts, increased oxygen consumption and ROS production. Ultimately, the lung interstitium becomes fibrotic causing difficult for the lungs to expand and contract. This makes it difficult for oxygen to pass from the lungs to the blood stream. Furthermore, the formation of Nitric Oxide in the presence of NOS causes damage to DNA and mitochondria (Kowalewski, 2022). Silica can influence epithelial cell damage and subsequent carcinogenesis through several pathways (Kowalewski, 2022).

Studies of mice and rats exposed to silica showed an immunosuppressive response following initial inflammation that supported lung tumour growth (Kowalewski, 2022).


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 Health Effects

Silicosis is characterized by irregular opacities on chest radiographs, as well as lung fibrosis and inflammation (Baron et al., 2002; Wagner, 1997). Over time, silica exposure causes scarring in the lungs, impairing breathing ability. The three standard forms of silicosis are chronic, acute, and accelerated silicosis.

Chronic silicosis, typically presents after more than 10 years of exposure, is characterized by progressively worsening dyspnea. Chronic silicosis is often mistaken for aging, and a cough that may be accompanied by sputum production or may be dry, especially in smokers and those exposed to dust (Wagner, 1997). Radiographic abnormalities may be detected before symptoms become apparent. Acute silicosis presents rapidly after a person is exposed to a high level of RCS and often comes with symptoms such as shortness of breath, chest pain, fever, fatigue and weight loss. These symptoms are often accompanied with visible abnormalities on X-ray. Accelerated silicosis, develops from exposure lengths between 1 and 10 years. The symptoms include shortness of breath, cough, fatigue, chest pain, weight loss, and respiratory failure (Wagner, 1997).

Studies have demonstrated that persons exposed to RCS have increased risks for developing other conditions such as tuberculosis, secondary airway diseases and lung cancer (Baron et al., 2002). Furthermore, studies have shown that the relative risk of tuberculosis for someone with radiological silicosis is 4.01 (Ehrlich et al., 2021; Rees & Murray, 2020). The International Agency for Research on Cancer (IARC) has confirmed that silica has carcinogenic effects on several occasions (IARC, 2012).

Epidemiologic studies have found that silicosis may develop or progress even after occupational exposure has ceased (Baron et al., 2002). By recognising that silica is slowly cleared from the lung, a worker’s long-term mean exposure over months or years is ultimately predictive of lung disease (Rappaport et al., 2003).

Silicosis has no effective treatment to reverse its course (Wagner, 1998); supportive care is provided, and some patients may be considered for lung transplantation (Bang et al., 2015).

Prevalence and Incidence

Silicosis is a critical topic in global occupational health research, however due to the latency of the disease it is difficult to determine the prevalence and incidence of Silicosis. A crude mortality decline in Australia was seen from 1.8 per million during (1982-1984) to 0.5 per million (1997-1999) (Smith & Leggat, 2006), while the US death rate was 0.39 per 1 million (Bang et al., 2015). In 2017, silicosis accounted for 39% of pneumoconiosis cases (Hoy et al., 2022). Despite death rates declining from 2001-2010, younger individuals aged 15-44 still experienced fatalities (Bang et al., 2015). A significant decline in compensated silicosis cases was reported in NSW, Australia, in 2003 (Berry et al., 2004), but certified cases increased from nine (2015-2016) to 107 (2019-2020) (Hoy, 2022).

The construction industry is particularly affected by silicosis, with certain sectors experiencing higher exposure rates to respirable crystalline silica (RCS) (Doney et al., 2020). Among Xiangyang-Chongqing Railway construction workers, 93.4 per 1,000 had silicosis 40 years after dust exposure (Fan, 2014). Workers exposed to levels above occupational exposure limits face a lifetime silicosis risk above 5% (Nij & Hederik, 2005). In a survey, 80% of construction workers reported RCS exposure, and 61.8% reported high exposure (Si et al., 2016). In Australia, 22.4% of assessed stonemasons were diagnosed with silicosis (Hoy, 2022), while 56% of New Zealand construction workers exceeded 0.025 mg/m3 of RCS (Mclean et al., 2017). Over 2 million workers in the US are exposed to crystalline silica dust, with 100,000 having high-risk exposure, demonstrating a large disease burden (Yassin et al., 2005).

Exposure within the construction industry has not seen to be consistent throughout, with sectors such tile and terrazzo contractors, brick, stone, and related construction merchant wholesalers, masonry contractors, and poured concrete foundation and structure contractors having the greatest exposures (Doney et al., 2020). Thus, it is important to look at effectively monitoring workers in these sectors who are at the greatest risk of developing silicosis due to their exposure to RCS.

There is a lack of comprehensive evidence on the incidence and prevalence of silicosis, partly due to latency periods that make it challenging to accurately assess the situation. However, the available data demonstrates a clear issue, particularly concerning younger workers diagnosed early with acute and accelerated silicosis. The information highlights the need for more reporting and better systems of surveillance, as underreporting and insufficient monitoring contribute to inadequate protection measures for workers exposed to crystalline silica (Lappi et al., 2013; Blanc et al., 2015). Improved monitoring and reporting systems are vital for addressing the silicosis concerns in the construction industry and ensuring the health and safety of workers.

 Workplace Exposure to Silica

Workplace exposure standards (WES) aim to limit workers’ exposure to dangerous materials, such as RCS. The WES (in Australia) for RCS is 0.05 mg/m³ averaged over an eight-hour period (8-h time-weighted average or TWA) (WHSQ, 2022). In construction work there are a range of materials and activities that may result in RCS exposure.

Materials such as cement, concrete, aggregates, precast concrete products, bricks, tiles, blocks, pylons, pavers, grout, mortar, asphalt, sand, stone, wall panels, and geosynthetics may contain silica (Linch, 2002). Whilst activities like cutting, sawing, grinding, drilling, abrasive blasting, scabbling, and crushing concrete, brick, or stone generate RCS dust (WHSQ, 2022).

In inspected workplaces, 62% had silica exposure levels above the OHSA workplace exposure limit, but only 11% conducted silicosis screening for their workers (Deslauriers & Redlich, 2018). Linch (2002) reported TWAs of 2.8 mg/m3 for abrasive blasting activities, 3.3mg/m3 for drilling concrete highway pavement, 0.26 mg/m3 for concrete wall grinding and 10.0mg/m3 for concrete sawing. All of these figures were well above acceptable levels of RCS. Recent silicosis outbreaks have been linked to high-silica content artificial stone fabrication, affecting young workers with short exposure durations and rapid disease progression (Hoy et al., 2022; Reynolds & Jerome, 2021).

In the construction industry, crystalline silica exposure levels varied across occupations, emphasizing the need for proper monitoring and control (Yassin, 2005). Among construction workers, bricklayers had the highest median silica exposure, followed by laborers, operating engineers, and painters (Rappaport et al., 2003). Approximately 5% of masonry contractors in the construction industry are potentially exposed to RCS at levels at least twice the exposure limit (Doney et al., 2020).

In conclusion, the construction industry involves various materials and activities that expose workers to RCS, posing a significant risk of silicosis. Proper monitoring, control measures, and adherence to workplace exposure standards are necessary to ensure worker health and safety.

 Health Surveillance and Monitoring

Health monitoring for workers exposed to RCS includes collecting demographic, medical, and occupational history, standardised respiratory questionnaires, spirometry, chest X-rays, and tuberculosis screening (Deslauriers & Redlich, 2018; Seneveratnie et al., 2018). More sensitive screening methods, such as high-resolution CT scans, are better at detecting early signs of silicosis but are not as commonly used due to costs (Nicol et al., 2015).

Air monitoring is crucial in assessing worker exposure to silica dust. Air monitoring involves the collection and analysis of air samples to measure the concentration of RCS particles in a workers’ breathing zone. Air monitoring in the construction industry can prove challenging due to differing activities throughout the course of an 8-hour workday resulting in fluctuating silica exposure levels (Kowalewski, 2022). In many cases acute exposure may be high, but under the TWA levels,

Despite the clear risks, many construction workers are not undergoing complete assessments (Seneveratnie et al., 2018). Literature has shown that there is a clear underreporting and under recognition of silicosis and low worker’s compensation claims (Deslauriers & Redlich, 2018).

These findings highlight the need for improved health surveillance, monitoring, and reporting in the construction industry to better protect workers from the harmful effects of silica exposure.

Controls and Preventative Measures

Silicosis controls and prevention programs implement the hierarchy of controls to mitigate risks (Bang et al., 2015). Elimination, the most effective measure, involves completely removing the hazard by avoiding materials containing 1% or more crystalline silica and eliminating or minimizing RCS work processes during project planning and design stages.  Substitution replaces hazardous materials or processes with safer alternatives, such as using materials with a lower proportion of crystalline silica or substituting tasks that generate less airborne dust. Engineering controls involve designing or modifying equipment and workplaces to minimize exposure, including wet methods, local exhaust ventilation (LEV), enclosing RCS-generating equipment, and using fabrication rooms. Wet Methods and LEV has been seen to reduce dust by over 90% (Thorpe et al., 1999). Administrative controls include changes in work practices, policies, or procedures to reduce exposure, such as worker training, scheduling tasks when fewer workers are present, and implementing proper housekeeping and maintenance procedures.  Personal protective equipment (PPE) should be the last line of defence for workers that includes the use of respiratory protective equipment (with regular fit testing, training and maintenance) (Lahiri et al., 2005).

The cost-effectiveness of these interventions, measured in cost per Disability-Adjusted Life Year (DALY) averted, varied across countries analysed, with interventions coming cheaper in low-income countries. The cheapest intervention is the use of wet methods, with LEV in the middle and PPE the most expensive (Lahiri et al., 2005).

In conclusion, these control measures have demonstrated effectiveness in reducing silica exposure and associated health risks. However, from the information on the incidence, prevalence and exposures, it is clear that these methods are not being adequately utilised in many workplaces, especially those with lower resources allocated to improving worker safety.

 Literature Quality

The literature on silicosis in the construction industry presents a wealth of information but also has notable weaknesses and gaps. First, the lack of comprehensive data on the incidence and prevalence of silicosis due to latency periods and underreporting presents a challenge in understanding the true extent of the issue. Furthermore, current exposure standards still present risks for workers, thus more research is needed to evaluate what is a safe level of exposure. Another limitation is the lack of studies that focus on the cost-effectiveness and long-term impact of control measures. By understanding this it would help employers to select the most viable and appropriate controls for their workplaces. Additionally, further benefits could be gained by assessing socio-economic factors that contribute to silicosis incidence and the barriers that exist in implementing effective controls. Addressing these weaknesses and gaps in the literature would provide a more complete understanding of silicosis in the construction industry and help inform future efforts in prevention, surveillance, and control.

 Implications for OHS – Now and the Future

The WHO and ILO have set a goal to end silicosis by 2030, however it is clear that there is a large amount of work to be done, particularly in the construction industry. What does this mean for OHS professionals moving forward?

There is a clear need for enhanced health surveillance programs, including baseline monitoring and continued, lifelong, monitoring for persons that are exposed to RCS as part of their work (Nicol et al., 2015).

Improving awareness of RCS and its risks is for both workers and Directors, because if a PCBU does not understand its responsibilities it cannot act on them (Reynolds & Jermone, 2021; Seneveratnie, 2018).

Consideration must be given to decreasing RCS exposure standards further as studies have shown that at the 0.05 mg/m3 level a percentage of the exposed population will develop the disease (Hoy et al., 2022). However, better methods for monitoring exposure must be developed to facilitate this change.

It is likely there will be increases in regulatory enforcement, such as restricting artificial stone fabrication to licensed businesses and considering importation bans if compliance doesn’t improve (Hoy et al., 2022).

A multidisciplinary approach should be undertaken amongst a range of disciplines to develop more effective controls, reduce risks to workers, and better understand the relationship between interventions and occupational exposures (Mmereki & Brouwer, 2022).

Increased research and funding can support more scientific studies to understand the onset, severity, incidence and prevalence and potential treatment options for silicosis, as well as the efficacy of implemented interventions (Rose et al., 2022).

Raising awareness among healthcare providers about the long-term effects of silica exposure and the importance of early detection and intervention is essential (Reynolds & Jermone, 2021).

An increase in accelerated and acute silicosis cases highlights the urgent need to improve disease surveillance, regulatory enforcement, and workplace exposure controls to protect these workers and prevent further silica dust exposure (Rose et al., 2022).


The literature review highlights the significant risks of silicosis among construction workers due to exposure to respirable crystalline silica (RCS). The review reveals that certain construction sectors are more susceptible to silicosis, and younger workers are at risk. The importance of workplace exposure standards and health surveillance programs is emphasized, but existing measures are insufficient.

The review demonstrates that although there are a range of effective controls and preventative measures available, their implementation is often insufficient, particularly in workplaces with limited resources allocated to worker safety. Moreover, the need for increased awareness and education about the risks of RCS exposure is emphasized, along with the importance of early detection and intervention.

The implications of these findings suggest that to achieve the WHO and ILO goal of ending silicosis by 2030, improvements in health surveillance programs, awareness, and regulation enforcement are crucial. Additionally, further research into the onset, severity, incidence, and prevalence of silicosis, as well as the efficacy of interventions, is required.


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