COMPUTATIONAL FLUID DYNAMICS SIMULATION OF FLOW OF EXHALED PARTICLES FROM POWERED-AIR PURIFYING RESPIRATORS.

Area of Science:

• Biomedical Engineering
• Infectious Disease Prevention
• Computational Fluid Dynamics

Background:

• Post-operative infections are often caused by wound contamination with infectious particles.
• Powered air-purifying respirators (PAPRs) are crucial for healthcare worker protection against infectious aerosols.
• Concerns exist regarding potential infectious particle expulsion from PAPR exhalation channels, posing a risk in sterile environments.

Purpose of the Study:

• To simulate and visualize the distribution of exhaled particles from PAPR wearers using computational fluid dynamics (CFD).
• To quantify the outward leakage of exhaled particles from PAPRs.
• To evaluate the impact of particle size, airflow rate, and breathing workload on particle leakage.

Main Methods:

• Developed a 3D geometrical model of a headform wearing a loose-fitting PAPR.
• Defined mathematical models for the headform and PAPR system.
• Conducted 24 CFD simulations varying particle size, breathing workload, and supplied air flow rates.
• Analyzed simulation results to determine particle concentration inside and outside the PAPR.

Main Results:

• Outward particle leakage from PAPRs is influenced by particle size, breathing workload, and supplied air flow rate.
• Leakage was approximately 9% for 0.1-1 micrometer particles at light breathing and 205 L/min airflow.
• Leakage ratio ranged from 7.6% to 49%, increasing with smaller particle size, higher workload, and lower airflow.

Conclusions:

• Supplied air flow rates and work rates significantly impact outward particle leakage from PAPRs.
• Understanding these factors is crucial for optimizing PAPR use and mitigating infection risks in healthcare settings.
• Simulation results provide a basis for future clinical studies on PAPR-related infection prevention.