Transcript Silica in Construction Sampling Data Compilation Project

Silica. It’s Not Just Dust
Rick Gleason, CIH, CSP
October 8, 2009
Rick Gleason, CIH, CSP
[email protected]
(206) 856-6660
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History of Silica
L & I Regulations
UW Airborne Silica Sampling
Questions
Hawk’s Nest Tunnel
West Virginia, 1932
Where is it found?
In Industry
In Nature
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Beach sand
Granite
Sandstone
Clays
Diatomaceous
earth
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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 longterm 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%
0%
mod. low
0.3
mod. high
high
* Flinn et al, 1939
1.5%
0%
3
24
51
85
0
7
20
59
71
4
19
48
71
80
Other Health Problems Related to
Silica Exposure
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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/m3
– compare to Washington PEL of 0.1 mg/m3
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Conc. (mg/m )
Quartz Concentration by Data Source
0.35
0.3
0.25
0.2
0.15
0.1
0.05
0
9%
up to 2 hr
2-6 hr
Sampling Time
over 6 hr
Private
36%
Research
55%
Regulatory
Exposure by Tool Used
Tool: abrasive blaster
No.= 57
0.28 mg/m3
Range 0.01 – 832.71 mg/m3
Tool: hand-held saw
No.= 65
0.13 mg/m3
Range <0.01 – 14.15 mg/m3
Tool: table saw
No.= 51
0.07 mg/m3
Range 0.01 – 2.75 mg/m3
Tool: walk-behind saw
No.= 33
0.09 mg/m3
Range 0.02 – 1.64 mg/m3
Tool: rock drill
No.= 93
0.21 mg/m3
Range <0.01 – 16.00 mg/m3
Tool: jackhammer/chipping gun
No.= 178
0.15 mg/m3
Range <0.01 – 3.86 mg/m3
Tool: broom/shovel
No.= 49 0.03 mg/m3
Range <0.01 – 1.19 mg/m3
Tool: surface grinder
No.= 123 0.28 mg/m3
Range 0.01 – 18.20 mg/m3
Tool: tuckpoint grinder
No.= 102 0.61 mg/m3
Range 0.01 – 76.10 mg/m3
Tool: concrete mixer
No.= 32
0.04 mg/m3
Range 0.01 – 0.55 mg/m3
Tool: backhoe/excavator/bulldozer/bobcat
No.= 28
0.01 mg/m3
Range <0.01 – 0.12 mg/m3
Tool: road mill
No.= 48
0.11 mg/m3
Range 0.01 – 16.10 mg/m3
Environment
No.
Conc.
Open
274
0.08
Enclosed
235
0.15
Confined
15
0.33
Project Type
Highway
N= 294 0.13 mg/m3 17%
Industrial/Commercial
N = 465 0.09 mg/m3 12%
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
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Abrasive blasting and grinding
Drilling, jackhammering, and chipping
Road demolition
Concrete cutting
Clean up and cement mixing
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
V
a
Metabo Grinder
Sawtec Shroud
Flex Grinder
and 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
Water Control
•Keep spray close to the
source
•Keep spray continuous
during dusty operations
•Keep water reservoir
filled
•Maintenance needed
to avoid clogging
Respirator Selection by Protection Factor *
none
5 x TLV
10 x TLV
**Based on monitoring data > 6 hours
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ta
b
ro
ad
m
w
ill
ill
ck
ro
ck
ha
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m
dr
r
de
ce
rfa
su
ja
gr
in
as
bl
ve
si
ra
ab
er
100 x TLV
te
r
% Not Protected
100
80
60
40
20
0
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
More information:
http://depts.washington.edu/silica/