Silica Dust: Using Table 1 on the Jobsite

Silicosis is irreversible and the exposure that causes it is invisible. Table 1 is the most practical route to compliance for most contractors.

Respirable crystalline silica is produced whenever concrete, masonry, brick, stone or engineered stone is cut, ground, drilled or crushed. The particles that cause harm are far too small to see. By the time a worker notices shortness of breath, lung damage has usually been accumulating for years, and silicosis has no cure.

The numbers

Under 29 CFR 1926.1153, construction employers must limit exposure to a permissible exposure limit of 50 micrograms per cubic meter of air as an 8-hour time-weighted average. The action level, which triggers exposure assessment and medical surveillance obligations, is 25 micrograms per cubic meter.

These are extremely small quantities. An amount of dust that looks trivial can exceed the limit over a shift.

Two compliance routes

Table 1 — a list of common construction tasks with specified control methods. Follow the entry for your task exactly and you are deemed compliant, with no requirement to perform air monitoring. For most contractors this is by far the simpler path.

Alternative exposure control — assess actual exposures through air sampling and implement controls that keep workers under the PEL. More flexibility, considerably more administrative work, and ongoing monitoring obligations.

What Table 1 covers

The table addresses the equipment most crews use every day, including:

• Handheld power saws cutting masonry or concrete
• Walk-behind saws
• Handheld and stand-mounted drills, including dowel drilling
• Jackhammers and handheld powered chipping tools
• Handheld grinders for mortar removal (tuckpointing) and for other applications
• Walk-behind milling machines and floor grinders
• Vehicle-mounted drilling rigs
• Crushing machines
• Heavy equipment used for demolition or grading

Each entry specifies the control — typically integrated water delivery or a dust collection system with a HEPA-filtered vacuum at a required airflow and filter-cleaning cycle — plus whether respiratory protection is required and at what level, often depending on whether the task is indoors or outdoors and how long it runs.

Follow the entry completely

This is where most Table 1 findings originate. Partial implementation does not confer the protection of the table:

• Water suppression means a continuous, adequate water feed. A saw with a dry or dribbling water line is not compliant, and it is producing dust.
• Dust collection means the specified airflow, the correct shroud or hood, a HEPA filter, and the filter-cleaning mechanism the entry calls for.
• Where the entry specifies respiratory protection, the full respirator program applies — fit testing, medical evaluation and training under 1910.134.
• Duration limits in the entry matter. Several entries change requirements past four hours of use in a shift.

The written exposure control plan

Every covered employer needs a written plan that:

• Describes the tasks involving silica exposure
• Describes the engineering controls, work practices and respiratory protection for each task
• Describes housekeeping practices
• Describes procedures used to restrict access to work areas where exposure could exceed the PEL

A competent person must be designated to implement the plan and to conduct frequent and regular inspections of job sites, materials and equipment.

Housekeeping is regulated

Dry sweeping and compressed-air cleanup of silica dust are prohibited where they could contribute to exposure, unless no safe alternative exists. Use HEPA-filtered vacuums or wet methods.

This is a habit change more than an equipment change, and it is the practice that most reliably reveals whether a program is real. Dry sweeping is fast and familiar, and it puts settled dust straight back into the breathing zone.

Medical surveillance

Medical surveillance must be offered to employees required to wear a respirator under this standard for 30 or more days per year. It includes a baseline examination and periodic examinations every three years, covering a chest X-ray and pulmonary function testing.

What to check today

Walk up to any saw, grinder or drill cutting masonry and ask three questions: is the specified control running, is it working properly right now, and does the operator know which Table 1 entry governs the task? If dust is visible in the air, the answer to at least one of those is no.