In quantitative fit testing for respirators, which instrument is used to measure seal leakage?

• A. Airflow meter.
• B. Condensation Particle Counter (CPC).
• C. Gas chromatography.
• D. Mass spectrometer.

Answer: (B)

In quantitative respirator fit testing, you detect seal leakage by counting how many aerosol particles penetrate the seal and enter the facepiece versus how many are outside. A condensation particle counter is designed to detect and count very small aerosol particles in real time, providing particle concentrations inside the mask and in the external environment. By comparing these concentrations, you can calculate the fit factor and quantify how much leakage occurs around the seal. The other instruments don’t serve this purpose: an airflow meter measures volumetric flow, not particle leakage, and gas chromatography or mass spectrometry analyze chemical compounds rather than real-time aerosol concentrations needed to assess seal leakage.