S I L I C A HAZARDS & CONTROLS. What are the hazards associated with exposure to silica dust, as well as basic preventive and control measures.

S I L I C AS I L I C A

HAZARDS

&

CONTROLS

What are the hazards associated with exposure to silica dust, as well as

basic preventive and control measures

Each year more than one million miners and other workers are

exposed to dangerous levels of the

dust - SILICA

DRILLERS

CRUSHER OPERATORS

BINSETTERS

QUALITY CONTROL TECH

SANDBLASTERS

PLANT HELPERS

MAINTENANCE PERSONNEL

MOBILE EQUIP. OPERATORS (without environmental cabs)

CHANGING SCREENS, BAG REPLACEMENT, BAGGING (without environmental booths)

CONFINED SPACE ENTRY

SILICOSIS HIGH RISK JOBS

Silica (Silicon Dioxide or SiO2) is found mainly as quartz in nearly all mineral deposits. It is found in common rocks such as granite, sandstone, limestone, and is the principle component of sand.

Where’s it come from?

Crystalline Silica

• Quartz

• Cristobalite

• Tridymite

What Are Dusts?

• Solid particles suspended in air

• Generated by blasting, drilling, crushing, grinding, etc.

The Body Defends Against Dust By:

• Trapping larger particles in the nasal passages, throat, trachea, larynx

• Trapping particles in mucous and carrying them up the airways where they are coughed out or swallowed (mucociliary escalator)

Silica dust may be a hazard, if...

• it is in the respirable range: small enough to get into the air sacs (alveoli) ----basically less than 10 microns in size

• it is present in high enough concentrations

bronchiole

alveoli

How Does Silica Affect The Body?

• Silica particles build up in the lungs leading to a type of dust disease (pneumoconiosis) called silicosis

• Makes affected workers more susceptible to TB

• Causes cancer

Silicosis : Severity of Disease

• Depends on:Dust Concentration

Percent of free silica

Duration of exposure

Size of particles (respirable??)

Chronic Silicosis• Most common form

• Occurs after 20 - 45 years of exposure

• Inhaled dust causes scarring

• After years of exposure - massive fibrosis (scarring)

Accelerated Silicosis• Develops 5 - 10 years after start

of exposure

• May lead to massive fibrosis and death

Acute Silicosis• Occurs where silica concentrations

are very high

• Can cause symptoms within a few weeks to 4 or 5 years

• Rapidly FATAL

WARNING!! Even when affected workers

are removed from exposure, silicosis may continue to

progress

Development of Silicosis is:• More Likely With:

• Inadequate dust control measures

• Inadequate respiratory protection

• Lack of medical screening

• Lack of air monitoring

Medical Exams Include:

• Medical and work history

• Checkup to detect early signs of lung disease

• Chest x-ray (reviewed by “B” reader)

• Breathing test

• TB examination

Mine Operators Must Report

• Silicosis cases for which award of compensation or medical diagnosis is received by miner

Evaluate Worker Exposures By:

• Doing work area inspections

• Sampling, monitoring workers

• Observing work practices

•Monitoring: Personal Exposures

PEL = 10 mg / m3

% Quartz + 2

PERMISSIBLE EXPOSURE LIMIT

(PEL)

REDUCE Silica Exposures:

• Assess potential for exposure

• Use engineering controls, such as:Dust CollectorsEnvironmental cabs and boothsWater SpraysHEPA Filters and Vacuum (Don’t

cleanup with brooms/shovels)