Monthly Round Up of Important Ideas and Standards in
Industrial Hygiene and Safety
IN THIS ISSUE: Silica–Specified Exposure Control Methods
Under the Respirable Crystalline Silica Standard for Construction, OSHA has several methods to determine whether and how compliance is needed. These include:
- Scheduled Air Monitoring. This includes initial monitoring to assess the 8-hour TWA exposure for each employee on the basis of one or more personal breathing zone air samples that reflect the exposures of employees on each shift, for each job classification, in each work area. Periodic monitoring may be required based upon these results.
- Objective Data. Information, such as air monitoring data from industry-wide surveys or calculations based on the composition of a substance, demonstrating employee exposure to respirable crystalline silica associated with a particular product or material or a specific process, task, or activity. The data must reflect workplace conditions closely resembling or with a higher exposure potential than the processes, types of material, control methods, work practices, and environmental conditions in the employer’s current operations.
- Specified Exposure Control Methods. In Table 1 1926.1153(c)(1), employee tasks are identified of which the employer must properly implement the engineering controls, work practices, and respiratory protection specified for the task.
Table 1 lists the following equipment or tasks:
- Stationary masonry saws
- Handheld power saws (any blade diameter)
- Handheld power saws for cutting fiber-cement board (with blade diameter of 8 inches or less)
- Walk-behind saws
- Drivable saws
- Rig-mounted core saws or drills
- Handheld and stand-mounted drills (including impact and rotary hammer drills)
- Dowel drilling rigs for concrete
- Vehicle-mounted drilling rigs for rock and concrete
- Jackhammers and handheld powered chipping tools
- Handheld grinders for mortar removal (i.e., tuckpointing)
- Handheld grinders for uses other than mortar removal
- Walk-behind milling machines and floor grinders
- Small drivable milling machines (less than half-lane)
- Large drivable milling machines (half-lane and larger)
- Crushing machines
- 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
- Heavy equipment and utility vehicles for tasks such as grading and excavating but not including: Demolishing, abrading, or fracturing silica-containing materials
For each of these, required engineering and work practices along with required respiratory protection and the minimum assigned protection factor are listed. As an example, for engineering controls for stationary masonry saws, it states: “Use saws equipped with integrated water delivery system that continuously feeds water to the blade. Operate and maintain tool in accordance with manufacturer’s instructions to minimize dust emissions.” No respiratory protection is required.
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