Silicosis Prevention

Georgia Tech Safety and Health Consultation Program2 What is Silica? u Composes 15% of Earth’s Crust u Examples: –Sand, Granite, other “Hard” rocks u Quartz, most common u Crystalline Silica –has a diagnostic X-ray diffraction pattern

Georgia Tech Safety and Health Consultation Program3 Why Control Crystalline Silica Exposure? u 1. Toxicity is well documented u 2. Exposure control is feasible u 3. Widespread worker overexposure

Georgia Tech Safety and Health Consultation Program4 Potential for Silica Exposure: Widespread u Foundries u Ceramics Industry u Abrasive Blasting u Masonry/Concrete Construction u Manufacturing of cleaning agents u Mining Operations u Use of Coal (e.g., electric power generation)

Georgia Tech Safety and Health Consultation Program5 Hawk’s Nest Tunnel (Historical Example) u Gauley Mt., W. VA. u 1930 – 1935 u Miners at Site: –Approx. 800 u Estimated Deaths: –500 to 750

Examples of Silica Exposures in Construction Georgia Tech Safety and Health Consultation Program6

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10Tuckpointing

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Georgia Tech Safety and Health Consultation Program13 Silica and Mortality u 250 Worker deaths per year –(175 deaths/yr from trenching accidents) u Silicosis u Tuberculosis u Heart Disease u Lung Cancer? –Suspect Hum. Carcinogen –A2 (ACGIH)

Georgia Tech Safety and Health Consultation Program14 Health Effects u Chronic-Obstructive Lung Disease u Affects Aveolar Surface –Decreases Elasticity –Prevents Oxygen/Carbon Dioxide Exchange

Georgia Tech Safety and Health Consultation Program15 3 Classes of Silicosis u 1. Acute Silicosis (Highest Exp.) –Latency of weeks to 5 years u 2. Accelerated Silicosis (High Exp.) –Latency of 5 to 15 years u 3. Chronic Silicosis (Moderate Exp.) –Latency >15 years

Georgia Tech Safety and Health Consultation Program16 Silicosis Diagnosis u Made by Chest X-ray u X-ray must be read by qualified “B- Reader” u Silica Nodules are Non-Reversible

Georgia Tech Safety and Health Consultation Program17 Silicosis is not a Curable Disease u Prevention through Safe Workpractice is critical

Georgia Tech Safety and Health Consultation Program18 Silicosis Prevention Program u Engineering Control of Dust u Training on crystalline silica u Respiratory protection program u Work clothes, change and wash area

Georgia Tech Safety and Health Consultation Program19 Silicosis Prevention Program u Air monitoring program u Medical surveillance u Housekeeping and Regulated Areas u Recordkeeping

Controls for Silica

Georgia Tech Safety and Health Consultation Program21 Types of Engineering Controls u 1. Wet Methods u 2. Ventilated Tools u 3. Abrasive Blasting Controls: –Alternate Media –Alternate Processes

Georgia Tech Safety and Health Consultation Program22 Engineering Controls: 1. Wet Methods u Water suppression of dust u Very effective method u Requires supply of water and clean up

Georgia Tech Safety and Health Consultation Program23 Wet Methods: Joint Cutting

Georgia Tech Safety and Health Consultation Program24 Wet Methods: Portable Saw

Georgia Tech Safety and Health Consultation Program25 Wet Methods: Pre-planning

Georgia Tech Safety and Health Consultation Program26 Prohibit Dry Cutting ! u 8 X OSHA PEL –Time Weighted Average (TWA) u Cut approx. 20 blocks per shift

Georgia Tech Safety and Health Consultation Program27 Mason’s Water Pump

Georgia Tech Safety and Health Consultation Program28 Wet Methods: Block Cutting

Georgia Tech Safety and Health Consultation Program29 Wet Methods: Jack hammer, chipping hammer, etc.

Georgia Tech Safety and Health Consultation Program30 Engineering Control 2. Ventilation u Portable tools with dust exhaust: –Surface Grinders –Disc Grinders (tuck pointing) –Crack chaser –Scarifier –Descaler –Power chipping tools u Retrofit Dust hoods

Georgia Tech Safety and Health Consultation Program31 Control by Ventilation: Slab Cutting

Georgia Tech Safety and Health Consultation Program32 Control by Ventilation: Hand tools

Georgia Tech Safety and Health Consultation Program33 Control by Ventilation: Tuckpointing

Georgia Tech Safety and Health Consultation Program34 Control by Ventilation: Tuckpointing

Georgia Tech Safety and Health Consultation Program35 Engineering Controls: 3. Substitute Abrasives u Coal slag (“black beauty”) u Steel grit & steel shot u Aluminum oxide u Sodium Bicarbonate –(baking soda) u Dust Suppressed Sand u Frozen CO2 u Ag. Prod. (walnut shells, corn cobs)

Georgia Tech Safety and Health Consultation Program36 Blast and Recovery Systems u Permits multiple cycles of abrasive u Reduces cost of more expensive abrasives u Reduces fugitive emissions to Environment