Presentation on theme: "Silica. It’s Not Just Dust Rick Gleason, CIH, CSP October 8, 2009."— Presentation transcript:
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
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
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