“Crystalline Silica Exposure”
Health Hazard Information
for Construction Employees |
What is crystalline silica?
Crystalline silica is a basic component of soil, sand, granite, and
many other minerals. Quartz is the most common form of crystalline
silica. Cristobalite and tridymite are two other forms of crystalline silica.
All three forms may become respirable size particles when workers chip,
cut, drill, or grind objects that contain crystalline silica.
What are the hazards of crystalline silica?
Silica exposure remains a serious threat to nearly 2 million U.S. workers,
including more than 100,000 workers in high risk jobs such as abrasive
blasting, foundry work, stonecutting, rock drilling, quarry work and
tunneling. The seriousness of the health hazards associated with silica
exposure is demonstrated by the fatalities and disabling illnesses that
continue to occur in sandblasters and rockdrillers. Crystalline silica has
been classified as a human lung carcinogen. Additionally, breathing
crystalline silica dust can cause silicosis, which in severe cases can be
disabling, or even fatal. The respirable silica dust enters the lungs and
causes the formation of scar tissue, thus reducing the lungs’ ability to
take in oxygen. There is no cure for silicosis. Since silicosis affects
lung function, it makes one more susceptible to lung infections like
tuberculosis. In addition, smoking causes lung damage and adds to
the damage caused by breathing silica dust.
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| What are the symptoms of silicosis? |
Silicosis is classified into three types: chronic/classic, accelerated,
and acute.
Chronic/classic silicosis, the most common, occurs after 15-20
years of moderate to low exposures to respirable crystalline silica.
Symptoms associated with chronic silicosis may or may not be
obvious; therefore, workers need to have a chest x-ray to determine
if there is lung damage. As the disease progresses, the worker may
experience shortness of breath upon exercising and have clinical
signs of poor oxygen/carbon dioxide exchange. In the later stages,
the worker may experience fatigue, extreme shortness of breath,
chest pain, or respiratory failure.
Accelerated silicosis can occur after 5-10 years of high exposures
to respirable crystalline silica. Symptoms include severe shortness
of breath, weakness, and weight loss. The onset of symptoms takes
longer than in acute silicosis.
Acute silicosis occurs after a few months or as long as 2 years
following exposures to extremely high concentrations of respirable
crystalline silica. Symptoms of acute silicosis include severe
disabling shortness of breath, weakness, and weight loss, which
often leads to death. |
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For more information, contact your local OSHA office (listed in the
telephone directory under United States Government-Department
of Labor-Occupational Safety and Health Administration) or visit
OSHA’s website at www.osha.gov.
Where are construction workers exposed
to crystalline silica?
Exposure occurs during many different construction
activities. The most severe exposures have occurred during
abrasive blasting with sand to remove paint and rust from
bridges, tanks, concrete structures, and other surfaces.
Other construction activities that may result in severe
exposure include: jack hammering, rock /well drilling,
concrete mixing, concrete drilling, brick and concrete block
cutting and sawing, tuck pointing, tunneling operations.
How is OSHA addressing exposure
to crystalline silica?
OSHA has an established Permissible Exposure Limit,
or PEL, which is the maximum amount of crystalline
silica to which workersmay be exposed during an 8-hour
work shift (29 CFR 1926.55,1910.1000). OSHA also
requires hazard communication training for workers
exposed to crystalline silica, and requires a respirator
protection program until engineering controls are
implemented. Additionally, OSHA has a National Emphasis
Program (NEP) for Crystalline Silica exposure to identify,
reduce, and eliminate health hazards associated with
occupational exposures. |
What can employers/employees do to
protect against exposures to crystalline silica?
- Replace crystalline silica materials with safer substitutes, whenever possible.
- Provide engineering or administrative controls, where feasible, such as
local exhaust ventilation, and blasting cabinets. Where necessary to
reduce exposures below the PEL, use protective equipment or other
protective measures.
- Use all available work practices to control dust exposures, such as water
sprays.
- Wear only a N95 NIOSH certified respirator, if respirator protection
is required. Do not alter the respirator. Do not wear a tight-fitting
respirator with a beard or mustache that prevents a good seal between
the respirator and the face.
- Wear only a Type CE abrasive-blast supplied-air respirator for abrasive
blasting.
- Wear disposable or washable work clothes and shower if facilities are
available. Vacuum the dust from your clothes or change into clean
clothing before leaving the work site.
- Participate in training, exposure monitoring, and health screening and
surveillance programs to monitor any adverse health effects caused by
crystalline silica exposures.
- Be aware of the operations and job tasks creating crystalline silica exposures
in your workplace environment and know how to protect yourself.
- Be aware of the health hazards related to exposures to crystalline silica. Smoking adds to the lung damage caused by silica exposures.
- Do not eat, drink, smoke, or apply cosmetics in areas where crystalline
silica dust is present. Wash your hands and face outside of dusty areas
before performing any of these activities.
- Remember: If it’s silica, it’s not just dust.
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U.S. Department of Labor
Occupational Safety and Health Administration
OSHA 3177
2002 (Revised)
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