The CDC recently recommended that everyone wear face masks whenever out in public to help protect against the further spread of coronavirus. This neat video uses an old but unusual photography technique to show the effectiveness of using face masks.
As the coronavirus pandemic continues, it is crucial that we all follow the recommendations of authorities to help prevent the further spread of the virus. LaVision recently created the above video, which shows the effectiveness of face masks, underscoring the importance of following the CDC's recent recommendation that everyone wear face masks in public. The video takes advantage of the Schlieren technique. Invented by August Toepler in 1864 to study supersonic motion, the method has remained crucial to studying airflow, with industries like aeronautics frequently employing it to visualize such dynamic processes. The technique relies on using collimated light (light that doesn't diverge with distance). Any airflow will cause density variations that change the refractive index of the air, causing the collimated light to diverge and creating areas of contrast that show the otherwise invisible airflow. It is a very clever technique, and it shows how crucial it is that we take all possible protective measures during this time. Stay safe and healthy!
Sort of pissed at 3M on rumors their dealers are price gouging. But I bought N95 about 2 months ago. BOO 3M
Lee on left, Patrick on right
It is worth mentioning that this only applies to N95 masks, and masks surgeons use. The cheap flimsy ones you find at the pharmacy (or homemade ones) don't have anywhere near the same effect. Also, the example here is a bit biased, because the masked guy isn't doing any of the same things the maskless person is doing. No coughing, no wheezing. He's just standing there. Talking, perhaps, but no more.
Interesting, though this only demonstrates air flow and not particle transmission and movement. FWIW N95 masks, properly fitted only filter out 95% of particles 3 microns and less. N100 masks are 99.999% effective. For respiration, i.e. breathing in particles, these masks are extremely effective whereas a regular surgical mask is not rated though it may stop approximately 60%. The key is that any mask, even cotton will help to reduce the spread of droplets from infected people. One of the issues with this virus is that anywhere between 25-85% may be asymptomatic and shedding the virus. Thus wearing a simple mask makes sense to reduce the particles they spread into the environment even though it does little to protect the wearer against inhaling particles.
You actually hit on a pet peeve of mine - People wearing non-respirator masks (or respirator masks improperly fitted) as protection from others. Let's not get into how they put the mask on, or take it off, or the increased desire to touch one's face... :-)