Silica, Noise, and Respiratory Protection

Respirable Crystalline Silica (29 CFR 1926.1153)

Respirable crystalline silica (RCS) is fine quartz dust released when workers cut, grind, drill, or break concrete, brick, stone, and mortar. Particles small enough to reach the deep lung (the 'respirable' fraction) scar lung tissue permanently.

The key numbers — memorize them:

• PEL: 50 micrograms per cubic meter (ug/m3) as an 8-hour TWA.
• Action Level: 25 ug/m3 as an 8-hour TWA.
• Enforceable in construction since September 23, 2017 (2016 final rule).

Health Effects

Chronic RCS exposure causes:

• Silicosis — progressive, incurable fibrosis of the lung. It is irreversible, which is the entire reason engineering controls matter so much.
• Lung cancer — silica is an IARC Group 1 (confirmed) human carcinogen.
• COPD (chronic obstructive pulmonary disease) and kidney disease.

Table 1: The Compliance Shortcut

Table 1 of 1926.1153 lists 18 common construction tasks (stationary masonry saws, handheld power saws, jackhammers, handheld grinders, drilling rigs, and more). For each task it specifies the required engineering controls (water delivery or local exhaust ventilation), required work practices, and the respiratory protection needed for short vs. long durations.

The payoff: if an employer fully and properly implements the Table 1 controls for a task, it is not required to perform exposure monitoring or comply with the PEL for that task. Employers who go off-Table-1 must use the alternative exposure-assessment path (performance or scheduled monitoring) and meet the 50 ug/m3 PEL directly.

A classic Table 1 example: using a handheld power saw to cut concrete or masonry with an integrated water-delivery system is a listed task — water suppresses the dust at the blade. Other Table 1 tasks include stationary masonry saws, handheld grinders with local exhaust ventilation, jackhammers/rotary hammers, and drilling rigs with dust collection.

Every employer covered by the standard must also have a written exposure control plan, designate a competent person to implement it, restrict housekeeping methods that re-suspend dust (no dry sweeping or compressed air where a feasible alternative exists), and offer medical exams to workers required to wear a respirator for 30+ days/year. The medical exam includes a chest X-ray and lung-function (spirometry) test to catch early silicosis.

Occupational Noise (29 CFR 1926.52)

Noise-induced hearing loss is permanent and one of the most common construction illnesses. Loudness is measured in A-weighted decibels (dBA), which weight sound the way the human ear hears it.

The 5 dB exchange rate means allowable exposure time halves for every 5 dBA increase: 90 dBA for 8 hours, 95 dBA for 4 hours, 100 dBA for 2 hours, 105 dBA for 1 hour.

Nuance the exam may probe: the construction standard 1926.52 sets the 90 dBA PEL and requires feasible engineering/administrative controls plus a 'continuing, effective hearing conservation program' when exposures exceed the PEL. The explicit 85 dBA action level that triggers audiometric testing, training, and a formal Hearing Conservation Program is defined in the general-industry standard 1910.95, which construction practice and many exam items reference. Treat 90 dBA as the construction PEL and 85 dBA as the HCP/action-level figure.

Controls follow the hierarchy: quieter equipment and isolation first, then limiting time, then hearing protection devices (HPDs) — earplugs or earmuffs rated by Noise Reduction Rating (NRR).

Respiratory Protection (29 CFR 1926.103 / 1910.134)

29 CFR 1926.103 governs respirators in construction, and it incorporates 1910.134 by reference — so every general-industry respirator rule applies on a jobsite.

Before a worker may wear a tight-fitting respirator, the employer must, at no cost to the worker:

1. Medical evaluation — a questionnaire or exam to confirm the worker can safely wear a respirator (heart/lung stress).
2. Fit testing — qualitative or quantitative, done before first use and at least annually, and whenever the facepiece, face, or weight changes.
3. Training — proper use, limitations, donning/doffing, maintenance.

Additional requirements: a written respiratory protection program administered by a qualified program administrator, and a clean-shaven seal area (facial hair crossing the seal fails the fit).

Respirator types range from filtering facepieces (N95) and half-mask/full-facepiece air-purifying respirators (APRs) up to powered air-purifying respirators (PAPRs) and supplied-air respirators (SARs) for higher hazards or IDLH atmospheres.

Each respirator has an Assigned Protection Factor (APF) — the workplace level of protection it provides when worn correctly. A half-mask APR has an APF of 10 (reduces exposure to one-tenth), a full-facepiece APR has an APF of 50, and a properly fitted tight-fitting PAPR can reach 1,000. The hazard concentration divided by the APF must stay below the PEL when selecting a respirator.

Air-purifying respirators only filter contaminants from the surrounding air — they provide no oxygen and must never be used in oxygen-deficient (below 19.5%) or IDLH atmospheres, where only a supplied-air or self-contained breathing apparatus (SCBA) is acceptable. Cartridges and filters must be matched to the contaminant (particulate filters for dust, chemical cartridges for vapors) and changed on a schedule before breakthrough.

Worked Scenario & Traps

Air monitoring shows 22 ug/m3 of silica. Is the employer at or above the Action Level? No — 22 is below the 25 ug/m3 action level, so routine assessment-triggered programs are not mandated, though good practice still controls dust. Had the reading been 28, the AL would be exceeded.

Common mistakes: mixing the silica AL (25) with the lead AL (30); calling 90 dBA the action level (it is the PEL; 85 is the HCP trigger); and skipping fit testing or medical evaluation. Remember: medical evaluation and fit testing come BEFORE respirator use, and the employer always pays.