Content supplied by Pekin Insurance
What the Dust? Silica in the Construction Industry - Part 2
In our last blog, we established that exposure to respirable silica dust is a big problem for employees. So what can a contracting business employer do to reduce and eliminate this hazard to employees?
So What Are We Supposed to Do? Follow Table 1
For the construction industry, the new standard includes a guide referred to as Table 1, which can be considered the first line of defense. Table 1 is a fairly easy-to-follow list that outlines 18 common construction tasks along with exposure control methods and work practices that work well for those tasks and can be used to comply with the requirements of the standard.
Table 1 essentially outlines a series of controls which are described below:
- Employers must use engineering controls and work practices as the primary way of keeping exposures at or below the PEL. Engineering controls include wetting down work operations or using local exhaust ventilation (such as vacuums) to keep silica-containing dust out of the air and out of workers’ lungs. Another control method that may work well is enclosing an operation to contain the work to the specific area that the work is being performed in.
- Examples of work practices to control silica exposures include wetting down dust before sweeping it up or using the water flow rate recommended by the manufacturer for a tool with water controls.
- And last, respirators are only allowed when engineering and work practice controls cannot maintain exposures at or below the PEL.
In addition to following Table 1, all employers are required to:
- Establish and implement a written exposure control plan that identifies tasks that involve exposure and methods used to protect workers, including procedures to restrict access to work areas where high exposures may occur.
- Designate a competent person to implement the written exposure control plan.
- Restrict housekeeping practices that expose workers to silica where feasible alternatives are available.
- Offer medical exams—including chest X-rays and lung function tests—every three years for workers who are required by the standard to wear a respirator for 30 or more days per year.
- Train workers on work operations that result in silica exposure and ways to limit exposure.
OSHA Table 1—Specified Exposure Control Methods When Working With Materials Containing Crystalline Silica
| Equipment/task |
Engineering and work practice control methods |
Required respiratory protection and minimum assigned protection factor (APF) |
|
| ? 4 hours/shift |
>4 hours/shift |
||
| (i) Stationary masonry saws |
Use saw equipped with integrated water delivery system that continuously feeds water to the blade |
None |
None |
| (ii) Handheld power saws (any blade diameter) |
Use saw equipped with integrated water delivery system that continuously feeds water to the blade |
||
| -When used outdoors |
None |
APF 10 |
|
| -When used indoors or in an enclosed area |
APF 10 |
APF 10 |
|
| (iii) Handheld power saws for cutting fiber-cement board (with blade diameter of 8 inches or less) |
For tasks performed outdoors only: |
None |
None |
| (iv) Walk-behind saws |
Use saw equipped with integrated water delivery system that continuously feeds water to the blade |
||
| -When used outdoors |
None |
None |
|
| -When used indoors or in an enclosed area |
APF 10 |
APF 10 |
|
| (v) Drivable saws |
For tasks performed outdoors only: |
||
| Use saw equipped with integrated water delivery system that continuously feeds water to the blade |
None |
None |
|
| (vi) Rig-mounted core saws or drills |
Use tool equipped with integrated water delivery system that supplies water to cutting surface |
None |
None |
| (vii) Handheld and stand-mounted drills (including impact and rotary hammer drills) |
Use drill equipped with commercially available shroud or cowling with dust collection system |
None |
None |
| (viii) Dowel drilling rigs for concrete |
For tasks performed outdoors only: |
||
| Use shroud around drill bit with a dust collection system. Dust collector must have a filter with 99% or greater efficiency and a filter-cleaning mechanism |
APF 10 |
APF 10 |
|
| (ix) Vehicle-mounted drilling rigs for rock and concrete |
Use dust collection system with close capture hood or shroud around drill bit with a low-flow water spray to wet the dust at the discharge point from the dust collector |
None |
None |
| OR |
|||
| Operate from within an enclosed cab and use water for dust suppression on drill bit |
None |
None |
|
| (x) Jackhammers and handheld powered chipping tools |
Use tool with water delivery system that supplies a continuous stream or spray of water at the point of impact: |
||
| -When used outdoors |
None |
APF 10 |
|
| -When used indoors or in an enclosed area |
APF 10 |
APF 10 |
|
| OR |
|||
| Use tool equipped with commercially available shroud and dust collection system |
|||
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions |
|||
| Dust collector must provide the air flow recommended by the tool manufacturer, or greater, and have a filter with 99% or greater efficiency and a filter-cleaning mechanism: |
|||
| -When used outdoors |
None |
APF 10 |
|
| -When used indoors or in an enclosed area |
APF 10 |
APF 10 |
|
| (xi) Handheld grinders for mortar removal (i.e., tuckpointing) |
Use grinder equipped with commercially available shroud and dust collection system |
APF 10 |
APF 25 |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions |
|||
| Dust collector must provide 25 cubic feet per minute (cfm) or greater of airflow per inch of wheel diameter and have a filter with 99% or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism |
|||
| (xii) Handheld grinders for uses other than mortar removal |
For tasks performed outdoors only: |
None |
None |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions |
|||
| OR |
|||
| Use grinder equipped with commercially available shroud and dust collection system |
|||
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions |
|||
| Dust collector must provide 25 cubic feet per minute (cfm) or greater of airflow per inch of wheel diameter and have a filter with 99% or greater efficiency and a cyclonic pre-separator or filter-cleaning mechanism: |
|||
| -When used outdoors |
None |
None |
|
| -When used indoors or in an enclosed area |
None |
APF 10 |
|
| (xiii) Walk-behind milling machines and floor grinders |
Use machine equipped with integrated water delivery system that continuously feeds water to the cutting surface |
None |
None |
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions |
|||
| OR |
|||
| Use machine equipped with dust collection system recommended by the manufacturer |
None |
None |
|
| Operate and maintain tool in accordance with manufacturer's instructions to minimize dust emissions |
|||
| Dust collector must provide the air flow recommended by the manufacturer, or greater, and have a filter with 99% or greater efficiency and a filter-cleaning mechanism |
|||
| When used indoors or in an enclosed area, use a HEPA-filtered vacuum to remove loose dust in between passes |
|||
| (xiv) Small drivable milling machines (less than half-lane) |
Use a machine equipped with supplemental water sprays designed to suppress dust. Water must be combined with a surfactant |
None |
None |
| Operate and maintain machine to minimize dust emissions |
|||
| (xv) Large drivable milling machines (half-lane and larger) |
For cuts of any depth on asphalt only: |
None |
None |
| Operate and maintain machine to minimize dust emissions |
|||
| For cuts of four inches in depth or less on any substrate: |
|||
| Use machine equipped with exhaust ventilation on drum enclosure and supplemental water sprays designed to suppress dust |
None |
None |
|
| Operate and maintain machine to minimize dust emissions |
|||
| OR |
|||
| Use a machine equipped with supplemental water spray designed to suppress dust. Water must be combined with a surfactant |
None |
None |
|
| Operate and maintain machine to minimize dust emissions |
|||
| (xvi) Crushing machines |
Use equipment designed to deliver water spray or mist for dust suppression at crusher and other points where dust is generated (e.g., hoppers, conveyers, sieves/sizing or vibrating components, and discharge points) |
None |
None |
| Operate and maintain machine in accordance with manufacturer's instructions to minimize dust emissions |
|||
| Use a ventilated booth that provides fresh, climate-controlled air to the operator, or a remote control station |
|||
| (xvii) Heavy equipment and utility vehicles used to abrade or fracture silica-containing materials (e.g., hoe-ramming, rock ripping) or used during demolition activities involving silica-containing materials |
Operate equipment from within an enclosed cab |
None |
None |
| When employees outside of the cab are engaged in the task, apply water and/or dust suppressants as necessary to minimize dust emissions |
None |
None |
|
| (xviii) Heavy equipment and utility vehicles for tasks such as grading and excavating but not including: Demolishing, abrading, or fracturing silica-containing materials |
Apply water and/or dust suppressants as necessary to minimize dust emissions |
None |
None |
| OR |
|||
| When the equipment operator is the only employee engaged in the task, operate equipment from within an enclosed cab |
None |
None |
|
Lastly, employers who follow Table 1 correctly are not required to measure workers’ exposure to silica and are not subject to the PEL.
For employers who do not want to follow Table 1, the requirements are more stringent and require the following:
- Measure the amount of silica that workers are exposed to if it may be at or above an action level of 25 ?g/m3 (micrograms of silica per cubic meter of air), averaged over an eight-hour day.
- Protect workers from respirable crystalline silica exposures above the permissible exposure limit of 50 ?g/m3, averaged over an eight-hour day.
- Use dust controls to protect workers from silica exposures above the PEL.
- Provide respirators to workers when dust controls cannot limit exposures to the PEL.
Conclusion:
The health hazards and dangers of exposure to respirable crystalline silica are real but manageable. OSHA has offered options to employers that will take effort to implement, but the long-term outcomes and benefits to employees is immeasurable.
Sources: OSHA CFR 1926 Silica Standard and related OSHA bulletins
