“Crystalline Silica Exposure”

Health Hazard Information

for General Industry 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. 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.

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>.

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.
U.S. Department of Labor

Occupational Safety and Health AdministrationOSHA 31762002 (Revised)

Where are general industry employees

exposed to crystalline silica dust?

The most severe exposures to crystalline silica result

from abrasive blasting, which is done to clean and smooth

irregularities from molds, jewelry, and foundry castings,

finish tombstones, etch or frost glass, or remove paint, oils,

rust, or dirt form objects needing to be repainted or treated.

Other exposures to silica dust occur in cement and brick

manufacturing, asphalt pavement manufacturing, china and

ceramic manufacturing and the tool and die, steel and foundry

industries. Crystalline silica is used in manufacturing, household

abrasives, adhesives, paints, soaps, and glass. Additionally,

crystalline silica exposures occur in the maintenance, repair and

replacement of refractory brick furnace linings.

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 workers may 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 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?