silica. it’s not just dust rick gleason, cih, csp october 8, 2009
DESCRIPTION
Silica. It’s Not Just Dust Rick Gleason, CIH, CSP October 8, 2009. Rick Gleason, CIH, CSP [email protected] (206) 856-6660. 1. History of Silica 2. L & I Regulations 3. UW Airborne Silica Sampling 4. Questions. Hawk’s Nest Tunnel West Virginia, 1932. In Nature Beach sand - PowerPoint PPT PresentationTRANSCRIPT
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*
Dust Conc. Years in the Pottery Industry
0-9 10-19 20-29 30-39 > 40
low 0% 0.4% 1.5% 0% 0%
mod. low 0.3 3 24 51 85
mod. high 0 7 20 59 71
high 4 19 48 71 80
* Flinn et al, 1939
Other Health Problems Related to Silica Exposure
• Lung Cancer
• More susceptible to tuberculosis
• Maybe immune system disease
• Kidney disease
UW Research –ExposureWhat did we find?
• 1,375 personal quartz samples
• Geometric mean quartz concentration:– 0.13 mg/m3 – compare to Washington PEL of 0.1 mg/m3
00.05
0.1
0.15
0.2
0.25
0.3
0.35
Co
nc
. (m
g/m
3 )
up to 2 hr 2-6 hr over 6 hr
Sampling Time
Quartz Concentration by Data Source
Private
Research
Regulatory
9%
36%
55%
Huge Variability in Exposure
• Half of samples were below PEL (0.1 mg/m3)
• 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!
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
Respirator Selection by Protection Factor
020
4060
80100
% N
ot
Pro
tec
ted
none
5 x TLV
10 x TLV
100 x TLV
**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