We used smoke to show the airflow from the 3 most common types of mask, the blue 3 layer Face/Surgical mask and the KN95 Medical mask
Guidance is that mask and shields should fit close to the face to prevent exhaled droplets from the mouth and nose the mask should prevent these droplets being transmitted forwards and to the sides where they could infect people who are not socially distanced.
The KN95 is designed to seal to the face but it isn’t adjustable and only comes in one size so it often doesn’t seal as well as if should.
The most common disposable mask nearly always gapes at the side and crucially because of it’s shape actually directs air to either side of the wear potentially putting people at either side at risk
Although Clearshield is the least sealed of the three (Because it’s designed for easy breathing). The curved, rigid design of the shield directs exhaled air upwards in the same way as the KN95. Crucially there is very little sideways leakage.
All three masks do a good job of protecting people who are directly in front of the wearer which is the most important criteria
Only Clearshield and the KN95 mask did a good job of preventing sideways transmission.
Clearshield is the only solution that is comfortable enough to wear for long periods of time and that doesn’t encourage face touching which is the main cause of virus transmission.