There's a strong inhalation restriction with those as the only way for air to enter is through the mask filter. Of course there's much less restriction while exhaling, but there's still some since there's a valve there that you have to breathe out against. If I sneeze or cough a lot of it is getting caught inside of the mask filter too. But I'm not going to lie...I'm looking out for me first. I use these to clean my coop everyday so I know how much they keep out of my lungs.
Some of the masks I see people wearing are like wide open and flapping on the sides. Those aren't doing much to stop small droplets in and out either. I understand what others have posted and know that they may not be doing much...correlation obviously doesn't mean causation, but I'll keep wearing mine anyway. It's not causing harm to wear it.
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