Which of the following is a TIC emitter category?

• A. PAD
• B. Passive
• C. Active
• D. Direct

Answer: (B)

The concept here is how a toxic industrial chemical enters the air in a scenario. A passive emitter releases without any external energy input or deliberate actuation—think leaks, evaporation, or diffusion from a container or process. This kind of release happens naturally or due to equipment faults, not because something is being actively sprayed or pumped.

That’s why the correct choice is passive: it describes a release that isn’t powered or directed by an emission device. Active emitters involve some energy source to push the chemical into the environment, direct emitters imply a purposeful, targeted release, and PAD isn’t a standard emitter category in this context.