Crystalline Silica

Bryan Seal, CIH, CSP

Steve Delp, CAS

What is it?

• Silica is an oxide of Silicon (metal)

• Specifically it is Silicon dioxide

• It’s structure is crystalline

• Very hard

• Quartz

• Plain old sand

Where do you find silica?• Foundries that use sand in mold and core-making

processes• Steel and other metal processing – used in some

refractories• Coal mining• Quarries and cement mills• Oil and gas well fracking operations• Construction – concrete cutting, demolition,

removing old pointing

How are you exposed to silica?• Silica must be inhaled to be toxic

• Dust particles must be small enough to enter the lungs – Respirable (<10 microns)

• Any operations that create dust – falling sand, dry sweeping, cutting, grinding, blowing, shaking, dropping, chopping, shoveling and any other task that creates dust.

Health Effects - Silicosis• These small sharp crystalline particles

collect in the lungs and over time continuously cut and irritate the lung tissue.

• This causes scarring which decreases the oxygen transfer capability of the lung.

• It also decreases the elasticity of the lungs which decreases flow of air into and out of lungs

Health Effects - Silicosis• Silicosis is progressive and can be fatal –

15 – 20 Years

• Silica exposure has also been linked to lung cancer

• Accelerated Silicosis – 5-10 Years

• Acute Silicosis – A Few Months

• 200 Deaths Per Year

What must employers do?

• Know that there is silica in the workplace

• Know what the silica exposure levels are

• Provide training to employees

• Control or eliminate silica exposures through engineering controls

• Provide PPE

How workers can help?

• Recognize that silica may be present

• Adopt work practices that minimize exposure

• Wear PPE

What Is OSHA Doing?

• Standards (Prerule – OMB Fall 2009)

• General Industry• 1910.94, Ventilation• 1910.1000, Air contaminants

– Table Z-1, Limits for air contaminants – Table Z-3, Mineral dusts Silica PEL - 0.1 mg/M3 - Respirable

• Construction Industry• 1926.55, Air contaminants• 1926.57 Ventilation

Guidance – General Industry• "

Crystalline Silica Exposure" Health Hazard Information for General Industry Employees. OSHA Publication 3176, (2002). Discusses what silica is, what are its hazards, and what employers and employees can do to protect against exposures to silica.

• Crystalline Silica Exposure Health Hazard Information OSHA Fact Sheet, (2002) Provides information regarding silicosis disease and exposures.

• Crystalline Silica Exposure in General Industry. OSHA Health Hazard Information Card. Provides health hazard information and good work practices for workers.

Guidance – Construction Industry• Crystalline Silica Exposure Card for Construction. OSHA, (2002). Discusses

what silica is, what are its hazards, and what employers and employees can do to protect against exposures to silica.

• Crystalline Silica Exposure in the Construction Industry. OSHA.

• "Crystalline Silica Exposure" Health Hazard Information for Construction Employees. OSHA Publication 3177, (2002). Discusses what silica is, what are its hazards, and what employers and employees can do to protect against exposures to silica.

• Crystalline Silica Exposures in Construction. OSHA (Ellen I. Roznowski), (1997, July). Includes case studies and OSHA enforcement data.

• Controlling Silica Exposures in Construction OSHA Publication 3362-04, (2009). Provides information on the effectiveness of various engineering control approaches for several kinds of construction operations and equipment, and contains recommendations for work practices and respiratory protection.

Enforcement

• National Emphasis Program– National Emphasis Program – Crystalline Silica (CPL

03-00-007, 1/24/2008)– Local Emphasis Program – Concrete Block and Brick,

Concrete Products and Ready-Mixed Concrete (CPL 2012-06) – Pittsburgh Area Office

Letters of Interpretation (LOIs)

• 02/11/1991 1910.1200

Label requirements for crystalline silica.• 03/27/1998 1910.1000 & 1926.55

Special emphasis program for silicosis.• 05/12/1999 1910.134(a)(1) & 1910.134(a)(2)

Respirators for silica dust must be selected based on exposure levels.• 04/27/2005 1910.1000 Table Z-1; 1910.1000 Table Z-3;

1910.1200; 1910.1200(d); 1910.1200(g)

Requirements for maintaining Material Safety Data Sheets (MSDSs) for coal including coal dust, fly ash, and silica dust.

Wrap-up

• Identify, Quantify, Control

• Questions??

• Thank you for your attention