“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.

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.

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 <http://www.osha.gov>.
U.S. Department of Labor

Occupational Safety and Health AdministrationOSHA 31772002 (Revised)

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.

■ 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.

What can employers/employees do to protect against exposures to crystalline silica?