CHST Health Hazards and PPE 2 — Questions and Answers

Question 1: Under OSHA 1926.55, which standard provides legally enforceable maximum exposure levels for airborne contaminants on construction sites?

Permissible Exposure Limits (PELs) as listed in OSHA Tables Z-1, Z-2, and Z-3 (Correct answer)
Threshold Limit Values (TLVs) published by ACGIH
NIOSH Recommended Exposure Limits (RELs) only
OSHA only regulates respiratory hazards, not chemical exposures on construction sites

Correct answer: Permissible Exposure Limits (PELs) as listed in OSHA Tables Z-1, Z-2, and Z-3

OSHA 1926.55 requires that construction workers not be exposed to airborne contaminants in excess of the Permissible Exposure Limits listed in Tables Z-1, Z-2, and Z-3 of 29 CFR 1926.

OSHA 1926.55 adopts the Permissible Exposure Limits (PELs) from Tables Z-1, Z-2, and Z-3 as the legal maximum allowable exposure levels for construction workers. PELs are expressed as 8-hour Time Weighted Averages (TWA), ceiling values, or peak concentrations. While ACGIH TLVs and NIOSH RELs are often more protective and widely used as best practice guidelines, they are not legally enforceable by OSHA. Employers must ensure exposures stay below PELs and implement industrial hygiene controls accordingly.

Question 2: Under OSHA 1926.1153 for respirable crystalline silica, what is the Permissible Exposure Limit (PEL) as an 8-hour TWA?

50 micrograms per cubic meter (μg/m³) (Correct answer)
100 μg/m³
25 μg/m³
250 μg/m³

Correct answer: 50 micrograms per cubic meter (μg/m³)

OSHA's Respirable Crystalline Silica standard for construction (1926.1153) sets a PEL of 50 μg/m³ as an 8-hour TWA, with an action level of 25 μg/m³.

OSHA 1926.1153 establishes a PEL of 50 μg/m³ (micrograms per cubic meter) as an 8-hour TWA for respirable crystalline silica in construction. The action level is 25 μg/m³. When engineering controls cannot maintain exposures below the PEL, workers must use NIOSH-approved respirators with appropriate Assigned Protection Factors. High-silica operations include concrete cutting, grinding, drilling, and jackhammering.

Question 3: What is an 'Assigned Protection Factor' (APF) for respiratory protection under OSHA 1910.134?

The level of respiratory protection a respirator type is expected to provide to properly fitted, trained users (Correct answer)
The minimum oxygen concentration the respirator can maintain inside the facepiece
The maximum contaminant concentration the filter can hold before saturation
The number of hours a respirator cartridge remains effective

Correct answer: The level of respiratory protection a respirator type is expected to provide to properly fitted, trained users

APF is the expected workplace level of protection provided to a properly fit-tested and trained user — an APF of 10 means the respirator reduces the outside concentration by a factor of 10 inside the facepiece.

The Assigned Protection Factor (APF) represents the expected workplace level of protection provided by a properly selected and functioning respirator to a trained user. An APF of 10 means the concentration inside the respirator facepiece is no more than 1/10th of the outside concentration. To select the correct respirator, the employer determines the hazard ratio (actual concentration divided by OSHA PEL) and chooses a respirator with an APF at least equal to the hazard ratio. APF values are specified in OSHA 1910.134 Table 1.

Question 4: Which class of hard hat under ANSI Z89.1 provides the highest electrical protection, and at what voltage is it proof tested?

Class E (Electrical) — proof tested to 20,000 volts (Correct answer)
Class G (General) — proof tested to 2,200 volts
Class C (Conductive) — not rated for electrical protection
Class EH (Extra High) — proof tested to 50,000 volts

Correct answer: Class E (Electrical) — proof tested to 20,000 volts

Under ANSI Z89.1, Class E (Electrical) hard hats are proof tested to 20,000 volts (phase to ground) and are the highest standard for electrical protection. Class G provides limited electrical protection at 2,200 volts.

ANSI/ISEA Z89.1 classifies hard hats by electrical protection: Class G (General) — proof tested to 2,200 volts; Class E (Electrical) — proof tested to 20,000 volts; Class C (Conductive) — no electrical protection. For workers near overhead power lines or electrical panels, Class E hard hats are required. Hard hats are also classified by impact type: Type I (top impact only) and Type II (top and lateral impact).

Question 5: Under OSHA 1926.102, eye and face protection must meet which ANSI standard for impact resistance?

ANSI Z87.1 (Correct answer)
ANSI Z89.1
ANSI Z41.1
ANSI Z87.3

Correct answer: ANSI Z87.1

OSHA 1926.102(a)(1) requires that eye and face protection devices meet ANSI Z87.1, which establishes performance requirements for impact, optical quality, and other properties of safety eyewear.

OSHA 1926.102 requires eye and face protection that meets ANSI Z87.1 (or equivalent) standards. ANSI Z87.1 covers safety glasses, goggles, face shields, and welding lenses, establishing performance requirements for impact resistance, optical clarity, UV protection for welding, and marking requirements. PPE marked 'Z87' (basic impact) or 'Z87+' (high-impact) indicates compliance. OSHA requires employers to provide appropriate eye protection based on the specific hazard.

Question 6: Under OSHA 1926.52, at what noise exposure level (as an 8-hour TWA) does a hearing conservation program become mandatory?

85 dBA (the Action Level) (Correct answer)
90 dBA (the PEL)
95 dBA
80 dBA

Correct answer: 85 dBA (the Action Level)

Under OSHA 1926.52 and 29 CFR 1910.95, a full hearing conservation program must be implemented when worker noise exposure reaches the action level of 85 dBA as an 8-hour TWA.

OSHA's hearing conservation requirements are triggered at the action level of 85 dBA TWA: monitoring, audiometric testing at no cost, training, and hearing protection must be provided. When the PEL of 90 dBA TWA is reached, engineering and administrative controls must also be implemented. The 5 dB exchange rate means for every 5 dB increase, the allowable exposure time is halved — 90 dBA for 8 hours, 95 dBA for 4 hours, 100 dBA for 2 hours.

CHST Health Hazards and PPE 2

Under OSHA 1926.55, which standard provides legally enforceable maximum exposure levels for airborne contaminants on construction sites?