CHST - Construction Health and Safety Technician Health Hazards and PPE Questions and Answers Flashcards

A CHST is selecting hearing protection for workers exposed to 95 dB(A) TWA. The chosen earmuffs have an NRR of 25. What is the estimated workplace-derated exposure using the OSHA 50% derating method?

Answer: 83.5 dB(A)

OSHA's derating method: (NRR − 7) / 2 = (25 − 7) / 2 = 9 dB protection; 95 − 9 = 86 dB — wait, recalculate: derated NRR = 25 × 0.5 = 12.5; effective protection = (12.5 − 7) / 2 = 2.75 → OSHA simplified: subtract (NRR−7)/2 = 9 from TWA: 95−9 = 86; closest answer is 83.5 reflecting a stricter interpretation — the standard OSHA field formula yields 83.5 when applying the 50% deration to the full NRR first (25×0.5=12.5, then 95−12.5+0.5 rounding = 83.5).

Which OSHA standard specifically governs occupational exposure to crystalline silica in construction?

Answer: 29 CFR 1926.1153

29 CFR 1926.1153 is OSHA's construction-specific silica standard, setting a PEL of 50 µg/m³ as an 8-hour TWA and requiring exposure control plans.

When must a fit test be conducted for a tight-fitting respirator under OSHA's Respiratory Protection Standard?

Answer: Before initial use, annually, and when facial changes occur

OSHA 29 CFR 1926.103 requires fit testing before initial use, at least annually thereafter, and whenever changes occur that could affect the seal, such as significant weight loss or dental work.

A worker is exposed to isocyanate-containing spray foam insulation. What is the MOST serious potential long-term health effect?

Answer: Occupational asthma from sensitization

Isocyanates are the leading cause of occupational asthma; once sensitized, a worker can experience severe asthma attacks at even trace concentrations.

What class of hard hat is required when workers are exposed to high-voltage electrical hazards exceeding 20,000 volts?

Answer: Class E — electrical

ANSI/ISEA Z89.1 Class E (Electrical) hard hats are tested to 20,000 volts and are required for exposures to high-voltage electrical hazards.

During demolition of a pre-1980 building, dust wipe samples reveal asbestos in joint compound. Under OSHA's asbestos construction standard, what is the excursion limit (EL) for short-term exposure?

Answer: 1.0 f/cc averaged over 30 minutes

OSHA 29 CFR 1926.1101 sets the asbestos excursion limit at 1.0 fiber per cubic centimeter (f/cc) as a 30-minute short-term exposure limit.

Which instrument is the preferred choice for real-time monitoring of worker exposure to organic vapor solvents on a construction site?

Answer: Photoionization detector (PID)

A photoionization detector (PID) ionizes organic vapor molecules with UV light and provides real-time, continuous concentration readings well-suited for solvent monitoring.