Silica

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Silica
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WHAT IS SILICA?

• SILICA IS QUARTZ
• Quartz (silica) is found naturally in almost all
  rock, sand and soil.
• Silica is a principal component of sand
• It is found in all concrete products

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SILICA EXPOSURE IN INDUSTRY

• Sandblasting
• Foundry work
• Concrete mixing
• Concrete products
• Manufacturing
• Glass manufacturing
• Work with abrasives

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SILICA EXPOSURE
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SILICA EXPOSURE (cont)
DRILLING CONCRETE
CONCRETE CUTTING
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SILICA EXPOSURE (cont)
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SILICA EXPOSURE (cont)
SWEEPING AND BLOWING WITH AIR
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SILICA EXPOSURE (cont)
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WHAT IS SILICOSIS?

• Silicosis is one type of pneumoconiosis
• the medical term for lung scarring from inhaled
  dust.
• Pneumoconiosis can occur from inhaled asbestos,
  coal, beryllium, and other inhalable dusts.
• There is no effective treatment for any
  pneumoconiosis, including silicosis

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THREE TYPES OF SILICOSIS

• Simple chronic silicosis
• From long-term exposure (10-20 years) to low
  amounts of silica dust.
• Accelerated silicosis
• Occurs after exposure to larger amounts of silica
  over a shorter period of time (5-10 years).
• Acute silicosis
• From short-term exposure to very large amounts of
  silica dust.

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SILICOSIS ASSOCIATED RISKS

• Increased risk of tuberculosis lung cancer.
• Degree of increased risk
• is highly variable
• depends on several OTHER factors, including
• immune system
• exposure history (for TB),
• amount of lung scarring
• age
• smoking history (for cancer).

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SILICA EXPOSURE LIMITS
The safest amount of silica in the air is
zero. This is the legal limit set
In the air 100 micrograms per cubic meter
The legal limit is called a permissible exposure
limit or PEL. This limit is for respirable
(fine) dust.
Rule-ofthumb if dust containing silica is
visible in the air, its almost certainly over
the permissible limit.
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SILICA EXPOSURE CONTROL

• Silica dust exposure can be controlled by use of
  water or exhaust ventilation to reduce dust
• Capture or dispose of controlled dust
• Avoid dry sweeping and use of compressed air on
  concrete
• Respirators must be used if silica dust cant be
  controlled with water or ventilation

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SILICA EXPOSURE CONTROL

• HEPA vacuum cleaners can be used instead of
  sweeping and air blowing.
• Floors can be spray wet is sweeping is done.
• Exhaust systems must be inspected and maintained
• Areas with heavy traffic should be paved
• Speed limits shall be posted

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SILICA AND USE OF RESPIRATORS

• When respirators are used, the employer must
  establish a respiratory protection program
• outlined in the NIOSH Guide to Industrial
  Respiratory Protection NIOSH 1987a
• required in the OSHA respiratory protection
  standard 29 CFR 1910.134 and 1926.103.

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SILICA AND USE OF RESPIRATORS

• periodic environmental monitoring,
• regular training of personnel,
• selection of proper NIOSH-approved respirators,
• an evaluation of the worker's ability to perform
  the work while wearing a respirator,
• respirator fit testing, and
• maintenance, inspection, cleaning, and storage of
  respiratory protection equipment.

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SILICA AND USE OF RESPIRATORS

• One-piece dust masks can also be used, but are
  not recommended because they dont always fit
  properly and can leak.
• Respirators may still be needed even when steps
  have been taken to reduce the amount of dust in
  the air.
• A supplied air respirator is required if the
  amount of silica in the air is more than 10 times
  the permissible limit

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SILICA AND RESPIRATOR USE
Employees using respirators must be trained
Training is required for anyone who wears a
respirator. If you dont know how to use a
respirator properly, you may think your
respirator is providing protection when it is not.
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SILICA AND RESPIRATOR USE

• Respirators must fit properly to prevent leaks
  around the edges.
• Fit-testing must be done before first wearing a
  respirator.
• Beards are not allowed when wearing a respirator

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SUMMARY

• Remember silicosis can kill over time
• There is no cure for silicosis
• Keep dust down to a minimum
• Use engineering methods or process controls
• Last recourse use respirators