Silicosis Prevention. Georgia Tech Safety and Health Consultation Program2 What is Silica? u...

Silicosis PreventionSilicosis Prevention

Georgia Tech Safety and Health Consultation Program 2

What is Silica?What is Silica?

Composes 15% of Earth’s Crust Examples:– Sand, Granite, other “Hard” rocks

Quartz, most common Crystalline Silica– has a diagnostic X-ray diffraction

pattern


Why Control Crystalline Silica Why Control Crystalline Silica Exposure?Exposure?

1. Toxicity is well documented

2. Exposure control is feasible

3. Widespread worker overexposure


Potential for Silica Potential for Silica Exposure: WidespreadExposure: Widespread

Foundries

Ceramics Industry

Abrasive Blasting

Masonry/ConcreteConstruction

Manufacturing of cleaning agents

Mining Operations

Use of Coal (e.g., electric power generation)


Hawk’s Nest Tunnel Hawk’s Nest Tunnel (Historical Example)(Historical Example)

Gauley Mt., W. VA.

1930 – 1935

Miners at Site: – Approx. 800

Estimated Deaths:– 500 to 750

Examples of Silica Exposures Examples of Silica Exposures in Constructionin Construction



TuckpointingTuckpointing


Silica and MortalitySilica and Mortality

250 Worker deaths per year– (175 deaths/yr from trenching accidents)

Silicosis Tuberculosis Heart Disease

Lung Cancer?– Suspect Hum. Carcinogen –A2 (ACGIH)


Health EffectsHealth Effects

Chronic-Obstructive Lung Disease

Affects Aveolar Surface–Decreases Elasticity

–Prevents Oxygen/Carbon Dioxide Exchange


3 Classes of Silicosis3 Classes of Silicosis

1. Acute Silicosis (Highest Exp.)– Latency of weeks to 5 years

2. Accelerated Silicosis (High Exp.)– Latency of 5 to 15 years

3. Chronic Silicosis (Moderate Exp.)– Latency >15 years


Silicosis DiagnosisSilicosis Diagnosis

Made by Chest X-ray

X-ray must be read by qualified “B-Reader”

Silica Nodules are Non-Reversible


Silicosis is not a Curable Silicosis is not a Curable DiseaseDisease

Prevention through Safe Workpractice is critical


Silicosis Prevention ProgramSilicosis Prevention Program

Engineering Control of Dust

Training on crystalline silica

Respiratory protection program

Work clothes, change and wash area


Silicosis Prevention ProgramSilicosis Prevention Program

Air monitoring program

Medical surveillance

Housekeeping and Regulated Areas

Recordkeeping

Controls for SilicaControls for Silica


Types of Engineering ControlsTypes of Engineering Controls

1. Wet Methods

2. Ventilated Tools

3. Abrasive Blasting Controls:– Alternate Media– Alternate Processes


Engineering Controls:Engineering Controls:1. Wet Methods1. Wet Methods

Water suppression of dust

Very effective method

Requires supply of water and clean up


Wet Methods: Joint CuttingWet Methods: Joint Cutting


Wet Methods: Portable SawWet Methods: Portable Saw


Wet Methods: Pre-planningWet Methods: Pre-planning


Prohibit Dry Cutting !Prohibit Dry Cutting !

8 X OSHA PEL – Time Weighted

Average (TWA)

Cut approx. 20 blocks per shift


Mason’s Water PumpMason’s Water Pump


Wet Methods: Block CuttingWet Methods: Block Cutting


Wet Methods: Jack hammer, Wet Methods: Jack hammer, chipping hammer, etc.chipping hammer, etc.


Engineering ControlEngineering Control2. Ventilation2. Ventilation

Portable tools with dust exhaust:– Surface Grinders– Disc Grinders (tuck pointing)– Crack chaser– Scarifier– Descaler– Power chipping tools

Retrofit Dust hoods


Control by Ventilation: Slab Control by Ventilation: Slab CuttingCutting


Control by Ventilation: Hand Control by Ventilation: Hand toolstools


Control by Ventilation: Control by Ventilation: TuckpointingTuckpointing


Engineering Controls: Engineering Controls: 3. Substitute Abrasives3. Substitute Abrasives

Coal slag (“black beauty”) Steel grit & steel shot Aluminum oxide Sodium Bicarbonate– (baking soda)

Dust Suppressed Sand Frozen CO2 Ag. Prod. (walnut shells, corn

cobs)


Blast and Recovery SystemsBlast and Recovery Systems

Permits multiple cycles of abrasive

Reduces cost of more expensive abrasives

Reduces fugitive emissions to Environment

Silicosis Prevention. Georgia Tech Safety and Health Consultation Program2 What is Silica? u...

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