There are quite a few videos and experiments online that show the benefits of wearing a mask by holding a petri dish in front of their face while talking, singing, coughing etc., once with a mask and once without a mask. However, I have realised that while wearing a mask, despite the mask doing a good job blocking water droplets in the front, a lot of my breath (i.e. water droplets) goes to the sides of the mask.

Given that authorities are saying that the virus is airborne, I would think that the water droplets that come out of the side of the mask matter as well, especially in an enclosed room where many people would be spending their day. Has there been anyone who has put the petri dish at the side and did the same test as mentioned earlier? I can't seem to find any, but then again, my researching skills are not the best.

  • $\begingroup$ I’m voting to close this question because it is not about a problem in biology but appears to be an attempt to start a discussion. $\endgroup$
    – David
    Jul 26 at 13:02
  • 2
    $\begingroup$ @David Where would you suggest I ask this question then? I'm not looking to start a discussion. I'm asking if it had been tried before. I'm curious, in what way is this question attempting to start a discussion? $\endgroup$
    – prata
    Jul 26 at 13:06
  • $\begingroup$ I have no idea where you should post your question. All I can say is that this is a Question and Answer site about problems in Biology as made very clear in the Tour and Help on asking questions. This is the SE model and what makes SE distinct and valuable. $\endgroup$
    – David
    Jul 26 at 13:12
  • 2
    $\begingroup$ A properly-fitting mask should not have any breath/droplets leaking out the sides of the mask. $\endgroup$
    – Armand
    Jul 26 at 14:34
  • $\begingroup$ @Armand While that is true, what percentage of the population would/is actually wear/wearing a properly fitting mask? (rhetorical qn) A large number of people either wear surgical masks, which have huge gaps at the sides or cloth masks, which don't fit the face exactly. $\endgroup$
    – prata
    Jul 27 at 16:06

While I'm not sure about the petri dish experiment, I will answer the main question I think you're asking: how important is the air that escapes out of the sides/top of the mask?

This question is answered with really cool visuals in this paper: Visualizing the effectiveness of face masks in obstructing respiratory jets. While the main point of the paper aims to test the effectiveness of different masks in blocking coughs, you can see the trajectory of all the air (including the air coming out of the side). This example here shows a labelled diagram of air moving through and around through a folded handkerchief mask:

air leakage through weak mask diagram

Fig 3b

Looking at both the homestitched (top) and commercial masks (bottom) below, you can see that there isn't much leakage around the mask, and the leakage that does happen out of the top of the mask appears to stay close to the cougher:

homestitched mask

commercial mask

My interpretation is that the leakage around the mask is likely much less of a risk, since it probably is not moving as rapidly as air expelled directly out of the mouth--since the leaking air has already bounced off the mask, it does not get as far away from the person breathing/coughing. So, while stuff may escape out of the side/top, it doesn't get very far (hence the synergy of social distancing plus masking).

  • 1
    $\begingroup$ Here's another recent article on mask leakage effects: Cappa, C.D., Asadi, S., Barreda, S. et al. Expiratory aerosol particle escape from surgical masks due to imperfect sealing. Sci Rep 11, 12110 (2021). doi.org/10.1038/s41598-021-91487-7 $\endgroup$
    – Armand
    Jul 28 at 0:08

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.