11 training OSHA silica presentation 3 31 10 larry joswial MPH

What is silica?• Mineral – crystalline or amorphous forms – Crystalline most hazardous • Crystalline- 3 forms – Quartz, cristobalite, tridymite • Quartz – most common Major component of

Larry Joswiak, MPH

March 31, 2010

Silica 1926.55 – Mineral Dusts

• It’s not just dust…It’s

What is silica?

• Mineral – crystalline or amorphous forms

– Crystalline most hazardous

• Crystalline- 3 forms

– Quartz, cristobalite, tridymite

• Quartz – most common

Major component of soils and readily found in rock Granite ~30% quartz

Shale ~ 20% quartz Beach sand – nearly pure quartz

Silica Exposure Activities

Other Health Effects of Silica

• Diseased and healthy lung

• Compare these sections cut from a diseased lung with large cavities (left) and a pink, healthy lung (right) The diseased lung shows a case of miner’s phthisis (also known as silicosis) which has led to tuberculosis Quartz dust is inhaled by miners, and trapped in the lungs causes silicosis making the victim more susceptible to diseases such as tuberculosis and pneumonia.

Current Respirable Silica Quartz Exposure Limits

OSHA (PEL)

Construction

OSHA (PEL) General Industry ACGIH (TLV)

AIR SAMPLING EQUIPMENT

Personal

Air Pump

with

Cyclone

PERSONAL SAMPLING

OSHA Construction Industry OSHA General Industry Construction & General ACGIH

Industry Employee

Name

Sampled (minutes)

8 HR TWA a

(mppcf) e

PEL b

(mppcf) e

8 HR TWA a (mg/

m 3 ) d

PEL b

(mg/m 3 ) d

8 HR TWA a (mg/

m 3 ) d

ACGIH TLV f

Limit Values

Concrete Cutting (Dry) Example

30% Crystalline Silica Quartz

10% Crystalline Silica Quartz

10% Crystalline Silica Quartz

8 % Crystalline Silica Quartz

Silica Conclusions

• Dry operations: High

likelihood of silica dust

overexposure

• Wet operations: Low

potential for silica dust

overexposure

• Exposures may be

multiplied by factors such

as interior workplace and

corner location.

Silica Conclusions

• Written Hazard Communication Program

– Employee training on silica

• Engineering Controls

– Use of water during cutting

– Local exhaust ventilation