As the time required for mixing to the hazard concentration decreases, the hazard of a COTA cloud:

As the time required for mixing to the hazard concentration decreases, the hazard of a COTA cloud:

• A. Increases
• B. Decreases
• C. Remains the same
• D. Cannot be determined

Answer: (B)

The main idea is that hazard from a contaminant cloud depends on how concentrated it remains and for how long it stays above the hazardous level. Mixing the released material with surrounding air dilutes the plume. If the time required to mix down to the hazard concentration becomes shorter, the plume is diluted more quickly, so peak concentrations are lower and the duration above the hazardous level is shorter. That combination reduces the overall exposure and thus the hazard. If mixing were slower, the plume would stay more concentrated for longer and the hazard would be greater.

The main idea is that hazard from a contaminant cloud depends on how concentrated it remains and for how long it stays above the hazardous level. Mixing the released material with surrounding air dilutes the plume. If the time required to mix down to the hazard concentration becomes shorter, the plume is diluted more quickly, so peak concentrations are lower and the duration above the hazardous level is shorter. That combination reduces the overall exposure and thus the hazard. If mixing were slower, the plume would stay more concentrated for longer and the hazard would be greater.