HAZWOPER Hazard ID 3 — Questions and Answers
Question 1: Which DOT placard shape indicates a compressed gas hazard?
- Circle
- Diamond (square on point) (Correct answer)
- Rectangle
- Triangle
Correct answer: Diamond (square on point)
DOT hazard placards are diamond-shaped (square rotated 45°), each colored and numbered to indicate the specific hazard class.
Question 2: What hazard does the UN number 1993 on a placard indicate?
- Explosive material
- Flammable liquid, n.o.s. (Correct answer)
- Corrosive liquid
- Radioactive material
Correct answer: Flammable liquid, n.o.s.
UN 1993 is assigned to flammable liquids not otherwise specified (n.o.s.), a common placard number seen at hazardous waste sites.
Question 3: Which condition BEST describes an IDLH (Immediately Dangerous to Life or Health) atmosphere?
- Any atmosphere requiring Level C PPE
- An atmosphere posing immediate risk of death or irreversible health effects preventing escape (Correct answer)
- An atmosphere where oxygen levels are between 19.5% and 23.5%
- Any area where TLV-TWA has been exceeded
Correct answer: An atmosphere posing immediate risk of death or irreversible health effects preventing escape
NIOSH defines IDLH as any atmospheric condition that poses an immediate threat to life, health, or the ability to escape.
Question 4: A drum at a contaminated site has a radioactive trefoil symbol. Which initial action is MOST appropriate?
- Don Level A PPE and move the drum to the exclusion zone
- Establish a buffer distance and contact a radiological health physicist (Correct answer)
- Apply absorbent to any visible leaks and report findings
- Use a CGI to measure radiation levels around the drum
Correct answer: Establish a buffer distance and contact a radiological health physicist
Radioactive materials require specialized expertise; the first response is to maintain distance and involve qualified radiological personnel.
Question 5: Which property of a chemical determines how quickly it evaporates and contributes to inhalation hazard?
- Flash point
- Specific gravity
- Vapor pressure (Correct answer)
- Boiling point
Correct answer: Vapor pressure
Vapor pressure measures how readily a substance vaporizes at a given temperature; higher vapor pressure means faster evaporation and greater inhalation risk.
Question 6: What is the primary purpose of a hazardous waste site characterization survey?
- To determine the contractor responsible for cleanup
- To identify types, quantities, and locations of hazards before work begins (Correct answer)
- To establish billing rates for remediation work
- To select the final disposal facility for waste
Correct answer: To identify types, quantities, and locations of hazards before work begins
Site characterization identifies and documents hazard types, concentrations, and spatial distribution to inform safe work planning under 29 CFR 1910.120.
Question 7: Which of the following gases is heavier than air and tends to accumulate in low-lying areas such as manholes and trenches?
- Hydrogen cyanide (HCN)
- Carbon monoxide (CO)
- Hydrogen sulfide (H2S) (Correct answer)
- Ammonia (NH3)
Correct answer: Hydrogen sulfide (H2S)
Hydrogen sulfide (H2S) has a molecular weight of 34 g/mol, making it heavier than air (29 g/mol) and prone to pooling in confined low areas.
HAZWOPER Hazard ID 3
Which DOT placard shape indicates a compressed gas hazard?