Why is Silica Hazardous?
Silica, often referred to as quartz, is a very common mineral. It is found in many materials common on construction sites, including soil, sand, concrete, masonry, rock, granite, and landscaping materials.
The dust created by cutting, grinding, drilling or otherwise disturbing these materials can contain crystalline silica particles. These dust particles are very small. You cannot see them. This respirable silica dust causes lung disease and lung cancer. It only takes a very small amount of airborne silica dust to create a health hazard.
Recognizing that very small, respirable silica particles are hazardous, the Occupational Safety and Health Administration (OSHA) regulation 29 CFR 1926.1153 requires construction employers to keep worker exposures at or below a Permissible Exposure Level (PEL) of 50 µg/m3 or comply with Table 1 – Specified Exposure Control Methods When Working With Materials Containing Crystalline Silica of the silica standard (click here to learn more about the construction standard).
What’s the Risk?
A worker’s chance of becoming ill from exposure to silica dust depends on the tasks performed, the amount of dust they are exposed to, and the frequency of the exposures. Each exposure to silica adds into the total load of silica in the lungs – in other words, each exposure adds to the lung damage.
Health professionals express the total silica dose one person accumulates over time as “mg/m3 years," usually calculated as an average exposure each year in mg/m3 multiplied by the number of years with that exposure, or by an estimated average for each year. As the total dose increases, so does the likelihood, or the risk, for developing silicosis, lung cancer, or chronic obstructive pulmonary disease (COPD). Some workers become ill after many years of low exposure levels, while other workers who perform less frequent but high exposure tasks can become ill with a lower cumulative exposure. Why? Because a high exposure to silica dust overwhelms the lungs’ defenses and most of the dust settles deep into the lungs where it does the most damage.
Researchers have developed estimates of the total dose likely to cause disease. For example:
Among granite workers in the U.S. the rate of death from silicosis doubled at a cumulative exposure of less than 1 mg/m3.
A recent study of pottery workers found high rates of silicosis, up to 20%, among workers with an average exposure of 0.2 mg/m3 over many years.
The likelihood of getting lung cancer from silica exposure follows a similar pattern, with a significant risk at levels around 0.2 mg/m3 over many years, or higher exposures in a shorter period of time.
There is less information available to estimate the risk for COPD, but there is documentation showing that about 25% of cement masons, bricklayers, and plasterers have COPD after many years of work in the trade.
These very general estimates do not take into account individual susceptibility or other exposures at work that add onto the injury caused by silica and lead to disease at an earlier age.
It is important to remember that repeated exposures to silica add up to a total dose that can cause serious lung disease. The kinds of exposures we see in high exposure tasks, such as sandblasting and tuckpointing, over time can give a worker enough exposure to put him or her at serious risk for a silica-related illness.
Who’s At Risk?
Approximately 2.3 million workers in the U.S. are exposed to silica. Each year, hundreds of workers die from illnesses caused by breathing in silica and thousands more become ill.
Any construction worker who performs one or more of the following tasks with any of the materials listed below is at risk of being exposed to hazardous levels silica dust. If you work close by someone generating silica dust you may be at risk.
Asphalt (for paving)
Fiber Cement products
Paints containing silica
Roofing tiles & pavers
Soil (fill dirt and top soil)
Stone (including: granite, limestone, quartzite,sandstone, shale, slate, cultured, etc.)
Tile (clay, ceramic, concrete, etc.)
What are the Health Effects?
Inhaling crystalline silica can lead to serious, sometimes fatal illnesses including silicosis, lung cancer, tuberculosis (in those with silicosis), and chronic obstructive pulmonary disease (COPD). In addition, silica exposure has been linked to other illnesses including renal disease and other cancers.
Signs & Symptoms
Silica causes permanent lung damage that can be disabling and potentially lead to death. When workers inhale crystalline silica, the lung tissue reacts by developing fibrotic nodules and scarring around the trapped silica particles. If the nodules grow too large, breathing becomes difficult.
Silica exposure can cause silicosis and people with silicosis are also at a higher risk of developing tuberculosis. There is no cure for silicosis, but it is 100% preventable. The three types of silicosis are:
Chronic silicosis, which usually occurs after 10 or more years of exposure to crystalline silica at relatively low concentrations;
Accelerated silicosis, which results from exposure to high concentrations of crystalline silica and develops 5 to 10 years after the initial exposure; and
Acute silicosis, which occurs where exposure concentrations are the highest and can cause symptoms to develop within a few weeks to 4 or 5 years after the initial exposure.
Silica and other dusts also cause COPD. COPD includes chronic bronchitis, emphysema, bronchiectasis, and chronic airway obstruction. In 2014, COPD ranked as the third leading cause of death in the U.S. with over 147,000 deaths. COPD is projected to become the third most common cause of death worldwide by 2020.
Symptoms from both silicosis and COPD may not be obvious and can initially include shortness of breath, chest pain, or a persistent cough. Silicosis and COPD can be severe enough to cause respiratory failure, which may eventually lead to death.
In addition, silica exposure has been linked to other illnesses including lung cancer and kidney disease.
Workers do not have to get sick when working with materials containing silica. Silica related illnesses are 100% preventable.
Assign an individual to control and monitor for silica on the job, such as a competent person – someone knowledgeable of applicable standards, is capable of identifying workplace hazards relating to the specific operation, and has the authority to correct them.
Use vacuums, water, substitutes, or different work practices to reduce or eliminate the dust.
Provide workers with respiratory protection when other controls are not enough, which are properly fitted and appropriate for the exposure.
Use a substitute material instead of sand when abrasive blasting. For a list of substitutes, click here.
Use all equipment and follow work practices provided to them by their employer to control the dust. The controls won’t work if they’re not used.
Be aware of the operations and the job tasks that can create crystalline silica exposures and know the steps that should be taken to prevent exposures.
Participate in training, exposure monitoring, and health screening and surveillance programs to monitor any adverse health effects caused by crystalline silica exposures.
Wear disposable or washable work clothes and shower if facilities are available. Vacuum the dust from your clothes and change into clean clothing before leaving the work site. Do not brush or blow the dust off! Do not bring dust home!
Be aware of the health hazards related to exposures to crystalline silica. Smoking adds to the lung damage caused by silica exposures.
Avoid eating, drinking, smoking, or applying cosmetics in areas where crystalline silica dust is present. Wash your hands and face outside of dusty areas before performing any of these activities.
Provide your doctor with a copy of the Physician’s Alert for Silicosis to ensure that you are properly diagnosed and treated. Many cases of silicosis and silica-related illnesses are misdiagnosed because physicians are unaware of their patient’s work history and unfamiliar with the signs associated with this occupational illness. Without proper diagnosis and reporting, workers cannot receive suitable medical treatment and advice.
As always, Costello Safety Consulting is available to help you protect your employees in any environment. We understand the dangers your workers face and the safety products available to keep them safe and productive.