Air monitoring: which statement is true?

• A. There are standard response curves that include all monitors.
• B. Conversion factors apply to every monitor.
• C. They are calibrated to a specific gas.
• D. They measure upper explosive limits.

Answer: (C)

Air monitoring devices are built to detect specific gases, and their readings are accurate only if the sensor is calibrated for that particular gas. The calibration process uses a known concentration of the target gas to establish the exact relationship between the sensor signal and gas amount. Because different gases and sensor chemistries respond differently, calibration is gas-specific, not universal across all monitors. That’s why the true statement is that these monitors are calibrated to a specific gas.

Other ideas aren’t quite right because there isn’t one standard response curve that applies to every monitor, conversion factors aren’t universal for all devices, and upper explosive limits are properties of a gas in air rather than something a detector directly measures.