What can make a pressure difference reading misleading? Measure small pressure differences only with known reference points, stable conditions and safe equipment boundaries.
Record the conditions
Keep location, time, weather, occupancy, system state, instrument or observation method and a nearby comparison area with the result.
State the limit
A single reading, photograph, sound or odor description cannot certify a concealed cause. Describe what the evidence directly shows and what remains inferred.
Safe next step
Stop ordinary observation when there is electrical or combustion danger, sewage, unstable materials, unsafe access, rapidly spreading water, suspected hazardous material or acute occupant symptoms. Continue with Pressure difference for a repeatable protocol, measurement limit and professional handoff boundary.
