1. S I L I C A
HAZARDS
&
CONTROLS

2. What are the hazards associated with exposure to silica dust, as well as basic preventive and control measures

3. Each year more than one million miners and other workers are exposed to dangerous levels of the dust - SILICA

4. SILICOSIS HIGH RISK JOBS
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

5. Where’s it come from?
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.

6. Crystalline Silica
Quartz
Cristobalite
Tridymite

7. What Are Dusts? Solid particles suspended in air
Generated by blasting, drilling, crushing, grinding, etc.

8. 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)

9. 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

10. 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

11. Silicosis : Severity of Disease
Depends on:
Dust Concentration
Percent of free silica
Duration of exposure
Size of particles (respirable??)

12. Chronic Silicosis Most common form
Occurs after years of exposure
Inhaled dust causes scarring
After years of exposure - massive fibrosis (scarring)

13. Accelerated Silicosis
Develops years after start of exposure
May lead to massive fibrosis and death

14. Acute Silicosis Rapidly FATAL
Occurs where silica concentrations are very high
Can cause symptoms within a few weeks to 4 or 5 years
Rapidly FATAL

15. WARNING!!
Even when affected workers are removed from exposure, silicosis may continue to progress

16. Development of Silicosis is:
More Likely With:
Inadequate dust control measures
Inadequate respiratory protection
Lack of medical screening
Lack of air monitoring

17. 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

18. Mine Operators Must Report
Silicosis cases for which award of compensation or medical diagnosis is received by miner

19. Evaluate Worker Exposures By:
Doing work area inspections
Sampling, monitoring workers
Observing work practices

20. Monitoring: Personal Exposures

21. PERMISSIBLE EXPOSURE LIMIT
(PEL)
PEL = 10 mg / m 3
% Quartz + 2

22. REDUCE Silica Exposures:
Assess potential for exposure
Use engineering controls, such as:
Dust Collectors
Environmental cabs and booths
Water Sprays
HEPA Filters and Vacuum (Don’t cleanup with brooms/shovels)

23. THE END !