176 / 2024-03-11 11:19:46

Effects of Wearing Filtering Facepiece Respirators on Particulate Deposition in the Respiratory Tract: An Experimental Study Based on a Simulated Respiratory System

Aerosol exposure,Respiratory protection,Respiratory deposition efficiency,Performance testing,Facial seal leakage,Airway simulation model

Wearing masks alters the airflow dynamics and particle size distribution of particles entering and exiting the respiratory tract, thus impacting particle exposure and deposition within the respiratory system. Despite its significance, a knowledge gap exists regarding the relationship between mask usage and particle exposure/deposition patterns in the respiratory tract. This study addressed this deficit by constructing an experimental setup simulating a human respiratory system (comprising nasal cavity, pharynx, trachea, and five generations of bronchi) to assess the protective performance of two commonly used masks under different sealing conditions. Experiments were conducted using high-concentration NaCl particles and three representative human-like respiratory flow rates (15, 50, and 85 L/min), testing three face seal scenarios (unsealed, nose-only sealed, and fully sealed). The findings revealed that both breathing patterns and mask conditions significantly influence particle exposure and deposition within the respiratory tract. At a specific location within the respiratory system, particle deposition efficiency exhibited a non-linear trend with increasing respiratory flow rate, initially rising before decreasing (R² = 0.9746), with the maximum predicted at a flow rate of 48.6 L/min. Both the mask's protective efficiency and overall protection efficacy (inclusive of superficial respiratory tract filtration) significantly increased with improved facial sealing (p < 0.05). Remarkably, enhancing the seal only around the nasal side area achieved nearly 98% of the full-seal protection effectiveness (p < 0.05). Both N95 masks and surgical masks effectively prevented particles from reaching the bronchi lower than the fifth-generation. Particle deposition efficiency increased with particle size, and masks demonstrated varying degrees of effectiveness for different particle sizes. However, overall, they significantly reduced the number of particles deposited. This study underscores the importance of proper mask fit and highlights that even modest improvements in sealing, particularly around the nasal region, can substantially enhance respiratory protection against particulate matter exposure.