Related Experiment Video
Updated: Jul 30, 2026

Safety Precautions and Operating Procedures in an (A)BSL-4 Laboratory: 3. Aerobiology
Published on: October 3, 2016
How protective are respirator assigned protection factors: an uncertainty analysis
T J Nelson1, M A Jayjock, C E Colton
1NIHS Inc., Ardentown, DE 19810, USA.
Abstract:
This investigation evaluated the risk of overexposure for a selected assigned protection factor by performing Monte Carlo simulations. A model was constructed to assess respirator performance by calculating the concentration inside the respirator. Estimates of the factors that affect respirator performance were described as distributions. The distributions used a worst case estimate for concentration in the workplace, the worst case for respirator performance (the fifth percentile person), and the worst case for exhalation valve leakage. A Monte Carlo analysis then provided estimates of the percentage of time that concentration inside the respirator exceeded the occupational exposure limit (OEL). For a half-facepiece respirator with an APF of 10, the calculations indicated a low risk of being exposed above an OEL, with mean exposures being controlled well below an OEL.
Related Concept Videos
Transmission-based Precautions II: Airborne and Protective Environment
Airborne precautions:
Use airborne precautions when treating patients known or suspected to have diseases that spread through the air—for example, tuberculosis or measles. These organisms are present in smaller droplets expelled by an infected person and...
Personal Protective Equipment
PPE Use in Healthcare Settings I: Donning
PPE Use in Healthcare Settings II: Doffing
Factors Affecting Pulmonary Ventilation
Alveolar Surface Tension
The alveolar fluid lines the luminal surface of the alveoli and exerts a force called surface tension. This force is caused by the polar water molecules in the liquid being more strongly attracted to each...
Relative Risk

