A study published in the prestigious peer-reviewed journal Cell confirms what was already obvious: SARS-CoV-2 can propagate through the nose, and if you want the mask to be effective, you should wear it on your nose.
Your nose is a superspreader
It's a sight we've all grown accustomed to: people wearing their mask "half-heartedly" -- covering their mouth but not their nose. The reasoning behind this is, presumably, that it's easier to breathe this way, and (again, presumably) this still counts as wearing a mask. But, as several studies have already shown, the nose is just as capable as the mouth at transmitting the novel coronavirus.
In a new study, researchers show that nose cells are significantly more likely to become infected and shed virus compared to the throat or lungs. Sure, the mouth may spread aerosols farther away, but the nose is more "contagious". So every time someone exhales through their nose, they are likely to generate a higher concentration of infectious particles than if they were breathing from their mouth.
Simply put, your nose is a superspreader.
This study was not aimed particularly at masks. Researchers were most interested in assessing the infectivity of different parts of the respiratory tract and studying how the virus can move down to the lungs.
However, a takeaway from this study is that blocking the nose offers greatly increased protection, limiting the spread of virus-carrying aerosols.
"Although speculative, if the nasal cavity is the initial site mediating seeding of the lung via aspiration, these studies argue for the widespread use of masks to prevent aerosol, large droplet, and/or mechanical exposure to the nasal passages."
Face masks are not perfect -- we know that already, and that was the main reason why widespread usage was recommended so late in the pandemic. But even so, they offer a great deal of protection, and study after study has shown that they are instrumental in our defense against the pandemic. Wearing a mask (and wearing it properly) can literally make or break the pandemic response.
Unfortunately, many people still refuse to wear face masks for political reasons or due to already debunked conspiracy theories. Scientific studies such as this one underline the importance of this protective measure, but whether or not people follow it, that's a completely different story.
The study has been published in Cell.