Exposure to fine particles of silica while cutting, drilling, and blasting has been shown to cause silicosis, a serious and sometimes fatal lung disease. Construction employees who inhale fine particles of silica may be at risk of developing this disease. The small particles easily become suspended in the air and, when inhaled, penetrate deep into employees’ lungs.
Although the primary effect of overexposure to silica dust is silicosis, let’s not forget employees may also suffer from lung, stomach and other cancers, tuberculosis, chronic obstructive pulmonary disorder, immune system effects, and kidney effects. The only way to prevent disease is to eliminate exposure to crystalline silica or reduce crystalline silica exposure to safe levels.
Silicosis is one of the world’s oldest known occupational diseases; reports of employees with the disease date back to ancient Greece. By 1800, many common names for the lung disease, such as “masons’ disease” were given to silicosis. Despite its different names through the centuries, silicosis is a single disease with a single cause–exposure to respirable crystalline silica dust.
There are three types of silicosis, depending upon the airborne concentration of crystalline silica to which a worker has been exposed:
Chronic silicosis may go undetected for years in the early stages; in fact, a chest X-ray may not reveal an abnormality until after 15 or 20 years of exposure. The body's ability to fight infections may be overwhelmed by silica dust in the lungs, making workers more susceptible to certain illnesses, such as tuberculosis. As silicosis progresses, you may exhibit one or more of the following symptoms:
If you believe you are overexposed to silica dust, visit a doctor who knows about lung diseases. A medical examination that includes a complete work history, a chest X-ray, and lung function test is the only sure way to determine if you have silicosis. The National Institute of Occupational Safety and Health (NIOSH) recommends medical examinations occur before job placement or upon entering a trade, and at least every 3 years thereafter.
If it is known or suspected silica is being used and it may be in the air, the next step is to determine how much is there. To do that, sample the air during the work being conducted.
Collecting an Air Sample: A trained specialist, such as a certified industrial hygienist, will use a combination device called a cyclone assembly and a sampling pump to trap tiny respirable silica particles from the air in the work environment.
Laboratory Analysis: After collecting the air sample, the next task is to select a competent laboratory that does quality analysis work. This is critical to determining compliance with the OSHA crystalline silica standard. The work in monitoring exposure is wasted if samples are mishandled or analyzed incorrectly.
It is important to know there is not one crystalline silica exposure limit for all cases. Rather, the limit is derived from a calculation that takes into account the percentage of quartz, cristobalite, tridymite, and respirable dust specific to your particular worksite.
OSHA regulation 29 CFR 1910.1000 Table Z-3 is used to determine the exposure limits for crystalline silica. Though this regulation is under the General Industry Standard, crystalline silica exposures in the Construction and Maritime Industries are subject to this same limit. Regulating these industries under the General Industry Standard is specifically addressed in Appendix E of the OSHA Special Emphasis Program (SEP) for Silicosis.
If you are a math whiz, you can calculate the degree of exposure which employees are exposed by following the instructions on OSHA’s “Determining Exposure Limits for Silica” webpage.
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