Start with the question, not the instrument list. A report should state what prompted the investigation, which spaces were in scope, what decision the client needed to make, and what was outside scope. Without that frame, even accurate measurements can be difficult to interpret.
Measurements need context. Carbon dioxide, particulate, temperature and humidity are useful because they help describe how a space behaves over time. They should be read alongside occupancy, HVAC operation, outdoor conditions, complaint timing and field observations—not treated as isolated pass/fail numbers.
The basis for interpretation should be visible in the sentence. Where ventilation is part of the question, ASHRAE Standard 62.1 may provide relevant context. Where a contaminant has an occupational limit, OSHA or ACGIH criteria may be relevant. The report should explain why a criterion was used rather than simply listing standards in an appendix.
A strong report also states limitations. A one-day investigation is a snapshot. An inaccessible room is a data gap. A complaint that cannot be reproduced during fieldwork is not proof that nothing occurred. Stating those limits makes the conclusion more defensible, not less.
Finally, look at the recommendations. “Continue to monitor” is often not enough. A useful recommendation identifies the likely contributor, the action, the priority, and how the client will know the condition has been corrected.