Which tool is useful to observe airflow patterns and pressure relationships between pollutant sources and surrounding rooms?

• A. Hygrometer
• B. Anemometer
• C. Chemical smoke pencil
• D. Thermal imaging camera

Answer: (C)

Visualizing how air moves and how pressure differences drive that movement is best done with a tracer that makes the flow visible. A chemical smoke pencil releases a fine, visible plume that rides with the air, so you can watch how air from a pollutant source travels into adjacent rooms, leaks under doors, or flows through cracks. Observing the smoke in real time lets you map flow paths and infer where higher or lower pressure zones are, showing the direction and mixing of air between spaces.

Other tools provide static or indirect clues rather than direct flow visualization. A hygrometer measures humidity, not how air moves. An anemometer rates air speed at a single point and requires moving around to piece together a pattern. A thermal imaging camera highlights temperature differences that can hint at drafts but doesn’t directly trace airflow paths or pressure relationships.