COSS Safety Skills 4 — Questions and Answers
Question 1: A safety professional is calculating the Incidence Rate (IR) for recordable injuries. The facility had 12 recordable injuries, 200,000 employees, and 450,000 hours worked. What is the correct IR?
- 5.3 (Correct answer)
- 4.0
- 2.7
- 6.0
Correct answer: 5.3
IR = (Number of injuries × 200,000) / Hours worked = (12 × 200,000) / 450,000 = 5.33, rounded to 5.3.
Question 2: Which of the following best describes the 'Swiss Cheese Model' of accident causation?
- Accidents occur from a single root cause that must be identified
- Multiple layers of defenses each have holes, and when holes align an accident occurs (Correct answer)
- Near-misses and accidents share the same direct causes
- Safety systems fail only when maintenance is neglected
Correct answer: Multiple layers of defenses each have holes, and when holes align an accident occurs
James Reason's Swiss Cheese Model illustrates that accidents occur when holes in multiple defensive layers (barriers) momentarily align, allowing a hazard to reach the victim.
Question 3: Under OSHA's General Industry standard, the minimum illumination level required in a first aid station is:
- 5 foot-candles
- 10 foot-candles
- 30 foot-candles (Correct answer)
- 50 foot-candles
Correct answer: 30 foot-candles
OSHA 29 CFR 1910.303 and Table S-1 specify a minimum of 30 foot-candles for first aid stations and infirmaries.
Question 4: A combustible dust explosion requires which five elements to be present simultaneously (the 'Dust Explosion Pentagon')?
- Fuel, oxygen, heat, chain reaction, and dispersion
- Fuel, oxygen, heat, ignition source, and confinement (Correct answer)
- Dust, air, moisture, heat, and ignition source
- Fuel, oxygen, heat, pressure, and spark
Correct answer: Fuel, oxygen, heat, ignition source, and confinement
The Dust Explosion Pentagon adds dispersion and confinement to the classic fire triangle, requiring fuel (dust), oxygen, heat (ignition), dispersion, and confinement for a dust explosion.
Question 5: In process safety, a Process Hazard Analysis (PHA) must be performed before initial startup of a covered process and then updated at least every:
- 3 years
- 5 years (Correct answer)
- 7 years
- 10 years
Correct answer: 5 years
OSHA's PSM standard (29 CFR 1910.119) requires PHAs to be updated and revalidated at least every five years after the initial PHA.
Question 6: Which of the following activities would require a hot work permit in a typical industrial facility?
- Using a cordless drill near a flammable storage cabinet
- Grinding operations in a zone containing flammable vapors (Correct answer)
- Changing electrical fuses in a panel box
- Using pneumatic tools near painted surfaces
Correct answer: Grinding operations in a zone containing flammable vapors
Grinding produces sparks and heat sufficient to ignite flammable vapors, classifying it as hot work requiring a permit when conducted in hazardous areas.
Question 7: A safety professional observes workers using ladders that extend 36 inches above the landing platform instead of the required amount. What is the OSHA-required extension above the upper landing?
- 18 inches
- 24 inches
- 36 inches
- 3 feet (36 inches) is correct (Correct answer)
Correct answer: 3 feet (36 inches) is correct
OSHA requires portable ladders used to access an upper landing surface to extend at least 3 feet (36 inches) above that surface, so 36 inches is actually compliant.
COSS Safety Skills 4
A safety professional is calculating the Incidence Rate (IR) for recordable injuries.
The facility had 12 recordable injuries, 200,000 employees, and 450,000 hours worked.
What is the correct IR?