Silica

WHAT IS SILICA?

SILICA IS QUARTZQuartz (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

SILICA EXPOSURE IN INDUSTRY

SandblastingFoundry workConcrete mixingConcrete products ManufacturingGlass manufacturingWork with abrasives

SILICA EXPOSURE

Generates moderate to heavy amounts of

dustGenerates

heavy amounts of dust

SILICA EXPOSURE (cont)

DRILLING CONCRETE

CONCRETE CUTTING

SILICA EXPOSURE (cont)

SWEEPING AND BLOWING WITH AIR

SILICA EXPOSURE (cont)

SILICA EXPOSURE (cont)

WHAT IS SILICOSIS?

Silicosis is one type of pneumoconiosisthe 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

THREE ‘TYPES’ OF SILICOSIS

Simple chronic silicosisFrom long-term exposure (10-20 years) to low

amounts of silica dust.

Accelerated silicosisOccurs 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.

SILICOSIS – ASSOCIATED RISKS

Increased risk of tuberculosis & lung cancer.

Degree of increased riskis highly variabledepends on several OTHER factors, including

immune system exposure history (for TB), amount of lung scarringage smoking history (for cancer).

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-of–thumb: if dust containing

silica is visible in the air, it’s almost certainly over the permissible limit.

SILICA EXPOSURE CONTROL

Silica dust exposure can be controlled by use of water or exhaust ventilation to reduce dust

Capture or dispose of controlled dustAvoid dry sweeping and use of

compressed air on concreteRespirators must be used if silica dust

can’t be controlled with water or ventilation

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

SILICA AND USE OF RESPIRATORS

When respirators are used, the employer must establish a respiratory protection programoutlined in the NIOSH Guide to Industrial

Respiratory Protection [NIOSH 1987a]required in the OSHA respiratory protection

standard [29 CFR 1910.134 and 1926.103].

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.

SILICA AND USE OF RESPIRATORS

One-piece dust masks can also be used, but are not recommended because they don’t 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”

SILICA AND RESPIRATOR USE

Employees using respirators must be trained

Training is required for anyone who wears a respirator.

If you don’t know how to use a respirator properly, you may think your respirator is providing protection when it is not.

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

SILICA AND RESPIRATOR USE

SUMMARY

Remember silicosis can kill over timeThere is no cure for silicosisKeep dust down to a minimumUse engineering methods or process

controls Last recourse use respirators