What should not be changed before the ventilation & airflow is understood? The safest answer begins by recording location, trigger and timing before assigning a cause.
What the question is testing
Air follows pressure differences and available leakage paths, so the room where a symptom appears may not contain the source. The question becomes more useful when it separates what happened first from what was noticed later.
A practical comparison
Compare fan-on and fan-off conditions Repeat the observation only under safe, comparable conditions and note what stayed unchanged.
Limits and next step
Do not block required ventilation, enter ducts or alter combustion-air paths without competent review. Use the connected atlas guide to build a bounded evidence packet and a clear professional handoff when needed.
Observe→Compare triggers→Repair source→Verify outcome
Living field guideThis useful article is public now. Sources, cases and graph connections continue improving without blocking publication.
