Measurement of cough-wind pressure: masks for mitigating an influenza pandemic.

To assess the degree to which face masks reduce the strength of cough-wind, we measured the wind pressure in front of the mouth with and without the wearing of masks. We found that any conventional masks made from paper, cotton gauze, or non-woven fabrics reduced the wind pressure to less than one-tenth that recorded when no mask was worn.

Masks for influenza patients: measurement of airflow from the mouth.

In case of a new influenza pandemic, provision of masks to coughing patients could be used to slow expansion of the epidemic. To quantitatively assess the efficacy of different masks, we used an ultrasonic anemometer to measure the velocity of airflow from the mouth in coughing. We found that even the cheapest paper masks reduced the air speed to less than 1/10, implicating their effectiveness in decreasing viral spread.