Which of the following options lists common QA/QC checks performed before and during data collection at a monitoring site?

• A. Regularly updating software without any calibration activities.
• B. Zero/span calibrations; flow integrity checks; instrument diagnostics; filter handling/weights; calibration gas checks; and periodic field audits.
• C. QA/QC checks are optional for ambient monitoring.
• D. Calibrations are performed only at startup, with no ongoing checks.

Answer: (B)

QA/QC checks before and during data collection ensure data quality by actively verifying instrument performance and data integrity throughout the monitoring session. The best choice includes zero/span calibrations to set the instrument’s baseline and response, flow integrity checks to confirm proper sample transport, instrument diagnostics to detect malfunctions, correct filter handling and weights to ensure accurate mass measurements, calibration gas checks to verify readings against known concentrations, and periodic field audits to ensure procedures and records are correct. Updating software alone doesn’t guarantee accurate measurements without calibration activities, QA/QC isn’t optional for ambient monitoring, and calibrations performed only at startup fail to catch drift or degradation that occurs during the run.