OHST Practice Questions (2026) — Free Sample Questions with Answers

Answer: D

Hazards are being eliminated, because near-miss reports have fallen steadily: Reads falling near-miss reports as fewer hazards; with observations and closures also falling, it more likely shows declining reporting.

No trend can be judged until the recordable injury rate begins to change: Waits for a lagging indicator to move, which defeats the purpose of tracking leading indicators.

Performance is stable, because recordable injuries are the most reliable measure: Recordables are a small-number lagging measure; a flat count of 0–1 per month cannot show the underlying trend.

All three leading indicators are declining, which signals rising risk: Correct. Observations, near-miss reporting and on-time closures are leading indicators, and all three fell for six straight months, a warning sign before injuries rise.

Leading indicators (observations, near-miss reports, corrective-action closure) measure prevention activity and can warn of trouble while lagging indicators such as recordables still look flat.

Answer: A

1. Formula: TWA = Σ(Cᵢ × tᵢ) ÷ 8 h.
2. Products: 96 × 2 = 192; 40 × 3 = 120; 18 × 2 = 36; 0 × 1 = 0 (µg/m³·h).
3. Sum = 348 µg/m³·h; TWA = 348 ÷ 8 = 43.5 µg/m³.
4. Compare: 30 µg/m³ action level ≤ 43.5 < 50 µg/m³ PEL (29 CFR 1910.1025), so action-level requirements such as periodic exposure monitoring apply.

43.5 µg/m³; above the action level and below the PEL: Correct. (96 × 2 + 40 × 3 + 18 × 2 + 0 × 1) ÷ 8 = 348 ÷ 8 = 43.5 µg/m³, which is at or above the 30 µg/m³ action level and below the 50 µg/m³ PEL.

49.7 µg/m³; above the action level and below the PEL: Divides by the 7 sampled hours instead of the 8-hour shift, leaving out the documented unexposed hour.

51.3 µg/m³; above the permissible exposure limit: Averages the three concentrations without weighting them by their durations.

96.0 µg/m³; above the permissible exposure limit: Reports the highest single sample, which is not a time-weighted average.

Weight each concentration by its duration and divide by 8 h; a documented unexposed period counts as zero, and the result is then compared with the action level and the PEL.

Answer: D

Clean the floor and place absorbent pads around the press base daily: Cleanup controls the immediate hazard but does nothing about why the oil was there.

Replace the leaking fitting and add it to the press PM checklist: Fixes the press (the fourth why), but the change process that let the checklist go stale will create the same gap on the next retrofit.

Retrain maintenance staff to inspect all hydraulic fittings at each PM: Targets the people doing PM, but the checklist they follow still omits new fittings; the system gap remains.

Require every equipment-change approval to include updating PM tasks: Correct. The last "why" is a management-system gap: the change process does not update maintenance tasks. Fixing it (and then the press checklist) prevents recurrence across all modified equipment.

Keep asking why until you reach a management-system cause that, once corrected, prevents recurrence beyond this one event.

Answer: D

"Warning" only, because flammability is listed first on the SDS: The order of hazards on the SDS does not set the signal word. The more severe word governs.

"Warning" and "Danger," one beside each related hazard statement: A label carries only one signal word.

No signal word, because the product has hazards with different signal words: Every classified hazard requires a signal word on the label. Having two classes does not remove it.

"Danger" only, because the more severe signal word takes precedence: Correct. When "Danger" applies to any hazard class, it is the only signal word used. "Warning" does not also appear (1910.1200 Appendix C).

One signal word per label; "Danger" overrides "Warning."

Answer: C

1. OR gate (level control fails): P = 1 − (1 − 0.10)(1 − 0.20).
2. P = 1 − (0.90)(0.80) = 1 − 0.72 = 0.28.
3. AND gate (overfill): P = 0.28 × 0.05 = 0.014.
4. Check: the answer is smaller than either input to the AND gate, as expected for an AND gate. The probability of overfilling is 0.014.

0.0010: Multiplies all three probabilities, treating the OR gate as an AND gate.

0.0050: Drops the stuck-valve branch and multiplies only the transmitter by the alarm (0.10 × 0.05).

0.014: Correct. Level control fails with P = 1 − (0.90)(0.80) = 0.28; overfill = 0.28 × 0.05 = 0.014.

0.28: Stops at the OR gate and leaves out the AND with the alarm failure.

Fault trees: AND gates multiply probabilities; OR gates combine them as 1 − Π(1 − P). Work from the basic events up to the top event.

Answer: C

1. Formula: T = (W/n) × (L/H).
2. Share per leg: W/n = 6,000 lb ÷ 2 = 3,000 lb.
3. Load factor: L/H = 10 ft ÷ 8 ft = 1.25.
4. T = 3,000 lb × 1.25 = 3,750 lb per leg.
5. Check: T is more than the 3,000-lb vertical share, as it must be when the legs are angled (here about 53° from horizontal); each leg and its hardware must be rated for at least 3,750 lb.

2,400 lb: Inverts the load factor (3,000 × 8/10), giving less than the vertical share.

3,000 lb: Splits the load between the legs but ignores the angle (the L/H factor).

3,750 lb: Correct. T = (6,000 ÷ 2) × (10 ÷ 8) = 3,000 × 1.25 = 3,750 lb per leg.

7,500 lb: Applies the L/H factor to the full load without dividing between the two legs.

Sling leg tension = each leg's share × L/H; shorter legs (smaller H for the same spread) raise the tension.

Answer: B

The day mechanic leaves his lock on and gives the key to the night mechanic: Each authorized employee must be protected by his own lock; handing over a key breaks the one-person, one-lock principle.

The night mechanic applies his own lock before the day mechanic removes his: Correct. 1910.147(f)(4) requires procedures for shift or personnel changes that ensure continuity of lockout protection, including an orderly transfer of lockout devices so that the equipment is never left without a lock.

The day mechanic removes his lock and the night mechanic locks out on arrival: This leaves a gap with no lock on the energy-isolating device.

The supervisor hangs a "Do Not Operate" tag until the night mechanic arrives: A tag in place of a lock on a lockable device, even briefly, gives less protection and breaks continuity.

At shift change, the oncoming authorized employee locks on before the off-going employee removes his lock, so protection never lapses.

Answer: A

Prove the tester on a known source, test each phase pair and to ground, prove it again: Correct. NFPA 70E and 1910.333(b)(2)(iv)(B) require a qualified person to verify de-energization with a test instrument; checking the tester on a known source before and after the test confirms that a "no voltage" reading is real.

Test only phase-to-ground on each conductor, because that is the path that shock current takes: Phase-to-phase testing is also needed; a phase can read zero to ground in some ungrounded or high-resistance-grounded systems while voltage remains between phases.

Press the motor start button; if the motor does not run, the circuit is de-energized: A "try" of the controls is part of lockout, but it does not prove that the conductors at the work point are dead.

Use a non-contact voltage detector on the cable jacket, since it needs no adjustment: A non-contact detector can miss voltage through shielding or a weak battery and is not an adequately rated test of each conductor.

Test before touch: verify the tester on a known source, test every phase-to-phase and phase-to-ground combination, then verify the tester again.

Answer: C

Benzene is present at 12 ppm, above the 1-ppm PEL, so respirators are required: Treats a nonspecific total reading as a benzene concentration; gasoline contains many hydrocarbons that also respond.

Benzene cannot be present, because a PID cannot detect aromatic compounds: Benzene's ionization potential (about 9.2 eV) is below 10.6 eV, so a PID detects it readily.

It is total ionizable VOCs as isobutylene; benzene needs a specific method: Correct. A PID is nonspecific: it responds to all compounds with ionization potentials below the lamp energy, reported in isobutylene equivalents. Benzene must be measured with a benzene-specific tube or a sorbent sample analyzed by the laboratory.

The reading shows the oxygen displaced by vapor, so the oxygen level is 12 ppm below normal: A PID measures ionizable vapors, not oxygen; oxygen is measured with an electrochemical sensor in percent.

PIDs and other broadband direct-reading instruments are screening tools; a specific contaminant in a mixture needs a compound-specific method.

Answer: D

Clean and bandage the puncture and let the worker return to work: Treats the injury as minor first aid; the small entry wound hides paint forced deep into the tissue.

Have the worker rest and report back if swelling develops within 24 hours: Delay is the main cause of amputation in injection injuries; waiting for symptoms loses the treatment window.

Apply ice and give an over-the-counter pain reliever: Masks symptoms and delays the urgent surgical care the injury needs.

Send him for emergency care at once, reporting an injection injury: Correct. High-pressure injection injuries look trivial but force paint or solvent deep along tissue planes; they are surgical emergencies, and early debridement greatly reduces the risk of amputation.

Injection injuries from airless sprayers, grease guns and hydraulic lines need immediate emergency surgical evaluation, whatever the wound looks like.

Answer: C

1. Reference durations: T = 8 / 2^((L − 90)/5). T(100) = 8 / 2² = 2 h; T(92) = 8 / 2^0.4 = 6.06 h; T(85) = 8 / 2^(−1) = 16 h.
2. Dose: D = 100 × (1/2 + 3/6.06 + 4/16) = 100 × (0.500 + 0.495 + 0.250) = 124.5%.
3. TWA: 16.61 × log₁₀(124.5/100) + 90 = 16.61 × 0.0951 + 90 = 91.6 dBA.
4. Check: the dose is above 100%, so the TWA must be above 90 dBA; 91.6 dBA is consistent.

89.5 dBA: Averaged the sound levels weighted by time, (100 + 3 × 92 + 4 × 85) / 8; decibels are logarithmic and cannot be averaged arithmetically.

90.0 dBA: Dropped the 85-dBA period, as if applying the 90-dBA PEL threshold; the stem includes all levels from 80 dBA for the action-level decision.

91.6 dBA: Correct. T(100) = 2 h, T(92) = 6.06 h, T(85) = 16 h; D = 100 × (1/2 + 3/6.06 + 4/16) = 124.5%; TWA = 16.61 log₁₀(1.245) + 90 = 91.6 dBA, above the 85-dBA action level and the 90-dBA PEL (29 CFR 1910.95).

95.0 dBA: Used a 3-dB exchange rate in the reference-duration formula; OSHA uses a 5-dB exchange rate.

Convert each level to an allowed time with the 5-dB exchange rate, sum C/T as a dose, then convert the dose to a TWA; never average decibels arithmetically.

Answer: D

Evacuate to the outdoor assembly area in the front parking lot for a head count: Going outdoors puts employees into the vapor cloud, the opposite of the order.

Open doors and windows to dilute any vapor that enters: Opening the building lets the cloud in; dilution with contaminated outdoor air does not help.

Leave in personal vehicles to get away from the site at once: Driving out sends people through the plume and clogs the routes responders need.

Close doors and windows, shut off the air handlers and move to interior rooms: Correct. Shelter in place keeps outdoor air out: close openings, shut down HVAC that draws outside air, go to interior rooms and wait for the all-clear.

Shelter in place when the hazard is outside and passing: seal the building, stop outside air and wait for the all-clear.

Answer: A

Level A: Correct. 29 CFR 1910.120 Appendix B: Level A (positive-pressure SCBA with a totally encapsulating, vapor-tight chemical suit) is selected when the greatest skin, respiratory and eye protection is needed, including unknown atmospheres with possible skin-absorptive vapors.

Level B: Level B gives full respiratory protection but its splash suit is not vapor-tight, so it does not protect skin against an unknown vapor that may be absorbed.

Level C: Level C uses an air-purifying respirator, which requires a known contaminant and concentration and adequate oxygen; none is known here.

Level D: Level D is a work uniform with no respiratory protection, used only where no atmospheric hazard exists.

Unknown contaminant + unknown concentration + possible skin hazard = Level A until monitoring and identification justify downgrading.

Answer: B

For the duration of each sampled worker's employment plus 30 years: Employment plus 30 years is the medical-record rule (1910.1020(d)(1)(i)), not the exposure-record rule.

At least 30 years, even though the exposure has now ended: Correct. 29 CFR 1910.1020(d)(1)(ii): each employee exposure record must be kept for at least 30 years. Ending the process does not shorten the period.

For 5 years after the end of the year the exposure ended: Five years following the end of the year is the OSHA 300 Log retention rule (1904.33), not the exposure-record rule.

Only 1 year, provided that a summary of the results is kept: The 1-year allowance applies only to background data such as lab worksheets, and only when the sampling results themselves are kept for 30 years.

Exposure records (including air-sampling results): at least 30 years; only background data such as lab worksheets may go after 1 year. Medical records: employment + 30 years.

Answer: C

End-of-class satisfaction surveys: Surveys measure reaction (Level 1), not job behavior.

A written post-test on the energy control procedure: A post-test measures knowledge (Level 2); knowing the steps does not show they are used.

Checklist observations of real lockouts weeks after training: Correct. Watching real lockouts some time after training measures behavior on the job (Kirkpatrick Level 3), which is what the manager asked for.

Comparing the plant's total recordable rate before and after: Recordable rates are Level 4 results, affected by many factors, and say little about lockout practice.

To show behavior change, observe performance on the job after training, not in the classroom.

Answer: B

Accept it, because the tablet will be used only for work tasks: A gift from a bidder during an evaluation creates a conflict of interest whatever it is used for.

Decline the tablet and tell the supervisor about the offer: Correct. The Code requires avoiding compromise of professional judgment by conflicts of interest; declining and disclosing protects the objectivity of the evaluation.

Accept it but disclose the gift after the purchase is decided: Late disclosure does not remove the conflict that existed while the bids were scored.

Accept it and donate it to the department to avoid personal gain: The bidder still gains influence over the evaluator, so the conflict remains.

BCSP Code of Ethics: conduct professional relations with integrity and avoid conflicts of interest; decline gifts from parties whose business you are evaluating and disclose the offer.