Silica. It’s Not Just Dust Rick Gleason, CIH, CSP October 8, 2009

Rick Gleason, CIH, CSP (206)

1. History of Silica 2. L & I Regulations 3. UW Airborne Silica Sampling 4. Questions

Hawk’s Nest Tunnel West Virginia, 1932

Where is it found? In Nature Beach sand Granite Sandstone Clays Diatomaceous earth In Industry Mining Quarrying Stone cutting Sand blasting Concrete & mortar work Cutting, grinding, drilling, sanding

Silica Exposure Size of particles - can it be inhaled deep into the lung? % silica in the dust Concentration How much time exposed each day? How often exposed?

What is Sililcosis A Fibrotic disease of the lungs – it scars the lung tissue Lung is less flexible and has less area for the exchange of oxygen Makes it difficult to do hard work and breath May be from short-term high exposure (acute) or long- term lower exposure (chronic)

Silicosis Incurable and irreversible May progress even after exposure has stopped This is completely preventable!

Risk of Developing Silicosis* * Flinn et al, 1939

Other Health Problems Related to Silica Exposure Lung Cancer More susceptible to tuberculosis Maybe immune system disease Kidney disease

Silica Exposures Labor and Industries Rules

Standard 10 (d) Sanitation and Cleanliness

Labor and Industries Industrial Hygiene Codes What year???

October 1, 1938

Video: Stop Silicosis 1938 Available from the L & I DOSH Video Lending Library

UW Research –Exposure What did we find? 1,375 personal quartz samples Geometric mean quartz concentration: –0.13 mg/m 3 –compare to Washington PEL of 0.1 mg/m 3

9% 36% 55%

Exposure by Tool Used

Tool: abrasive blaster No.= mg/m 3 Range 0.01 – mg/m 3

Tool: hand-held saw No.= mg/m 3 Range <0.01 – mg/m 3

Tool: table saw No.= mg/m 3 Range 0.01 – 2.75 mg/m 3

Tool: walk-behind saw No.= mg/m 3 Range 0.02 – 1.64 mg/m 3

Tool: rock drill No.= mg/m 3 Range <0.01 – mg/m 3

Tool: jackhammer/chipping gun No.= mg/m 3 Range <0.01 – 3.86 mg/m 3

Tool: broom/shovel No.= mg/m 3 Range <0.01 – 1.19 mg/m 3

Tool: surface grinder No.= mg/m 3 Range 0.01 – mg/m 3

Tool: tuckpoint grinder No.= mg/m 3 Range 0.01 – mg/m 3

Tool: concrete mixer No.= mg/m 3 Range 0.01 – 0.55 mg/m 3

Tool: backhoe/excavator/bulldozer/bobcat No.= mg/m 3 Range <0.01 – 0.12 mg/m 3

Tool: road mill No.= mg/m 3 Range 0.01 – mg/m 3

Environment Open Enclosed Confined No.Conc

Project Type Highway N= mg/m 3 17% Industrial/Commercial N = mg/m 3 12%

Huge Variability in Exposure Half of samples were below PEL (0.1 mg/m 3 ) 13% of samples were over 10 times the PEL! These extremely high exposures represented 9 of 12 tools

Prioritzing for Control 1.Abrasive blasting and grinding 2.Drilling, jackhammering, and chipping 3.Road demolition 4.Concrete cutting 5.Clean up and cement mixing 6.Heavy equipment demolition

Exposure Summary Control should focus on task and tool Degree of enclosure and type of project are also important There is a problem – we need to move on to controlling it!

Vacuum on Tools 90% exposure reduction is possible LEV may reduce exposures below PEL

VacVac

Flex Grinder and Shroud Metabo Grinder Sawtec Shroud

Water Control Typically very effective High exposures can potentially result if: - Water application rate is low and/or - Work is enclosed Common for cutting - some other applications Problematic in some settings

Keep spray close to the source Keep spray continuous during dusty operations Keep water reservoir filled Maintenance needed to avoid clogging Water Control

* *Based on monitoring data > 6 hours *

Summary There is a problem – we need to move on to controls! Respirators currently used aren’t always protective enough We need to implement other controls or controls in combination with respirators

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