Airflow detailed analysis through a face mask using the schlieren technique

Area of Science:

• Fluid dynamics
• Aerosol science
• Public health

Background:

• Understanding airflow dynamics from respiratory activities is crucial for mitigating airborne disease transmission.
• Face masks are widely used to reduce the spread of infectious respiratory droplets.

Purpose of the Study:

• To visualize and quantify the airflow expelled by individuals wearing different types of disposable face masks.
• To compare the performance of surgical, KN95, and 3MN95 masks in controlling airflow and potential pathogen dispersal.

Main Methods:

• Utilized an optical schlieren experimental setup to visualize airflow characteristics.
• Measured refractive index gradient, temperature distribution, and velocity fields of expelled air.
• Tested three mask types: surgical, KN95, and 3MN95 (Aura TC-84A-8590).

Main Results:

• Surgical masks allowed the most abrupt output airflow.
• The KN95 face mask exhibited the best performance, expelling the least amount of airflow.
• Quantified expelled airflow velocity as a function of distance for each mask type.

Conclusions:

• Airflow behavior around face masks significantly impacts their efficacy in reducing pathogen transmission.
• The KN95 mask demonstrated superior performance in containing respiratory exhalations.
• Visualizing and understanding mask-associated airflow is vital for preventing the spread of airborne infectious diseases.