What is the purpose of field blank samples in IH air sampling?

• A. To calibrate instruments
• B. To determine humidity effects
• C. To identify laboratory or field contamination
• D. To measure sample volume

Answer: (C)

Field blank samples are a QA tool to reveal contamination introduced during the sampling process itself, before any air is drawn through the sampler. They travel through the same handling, transport, and analytical steps as real samples but do not expose the collection media to ambient air. If a field blank shows detectable levels of analyte, that indicates contamination from the sampling media, reagents, or the field environment, allowing you to distinguish true environmental concentrations from artifacts and to adjust or interpret results accordingly. They are not used for calibrating instruments, assessing humidity effects, or measuring sample volume, which rely on separate procedures and equipment.