1. NATIONAL PRECAST CONCRETE ASSOCIATION
SILICA & SILICOSIS

2. 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

3. SILICA EXPOSURE IN INDUSTRY
Sandblasting
Foundry work
Concrete mixing
Concrete products
Manufacturing
Glass manufacturing
Work with abrasives

4. SILICA EXPOSURE Generates moderate to heavy amounts of dust
Generates heavy amounts of dust
Generates moderate to heavy amounts of dust

5. SILICA EXPOSURE
Concrete Cutting
Concrete Drilling

6. SILICA EXPOSURE
Concrete Cutting
Concrete Sawing

7. SILICA EXPOSURE
Sweeping Concrete Dust
Blowing with Air

8. 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

9. 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.

10. 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)

11. SILICA EXPOSURE LIMITS
The safest amount of silica in the air is zero. This is the legal limit set by OSHA
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.
*Note: on June 23, 2018, the legal limit is set to be reduced to 50 micrograms per cubic meter.

12. 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 can’t be controlled with water or ventilation

13. SILICA EXPOSURE CONTROL
HEPA vacuum cleaners can be used instead of sweeping and air blowing.
Floors can be sprayed with a water mist while sweeping is done.
Exhaust systems must be inspected and maintained
Areas with heavy traffic should be paved
Speed limits shall be posted

14. SILICA AND 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 and ].

15. SILICA AND 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
Maintenance, inspection, cleaning and storage of respiratory protection equipment.

16. SILICA AND 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

17. SILICA AND RESPIRATORS
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.

18. SILICA AND RESPIRATORS
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

19. 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
When needed: use respirators