Yes, unfortunately, having thick facial hair can stop a mask from sealing. We do however have many customers with facial hair who use our products. If the edges of the filter are lifted off the skin slightly, polluted air can leak in. Customers with facial hair should understand that they are not sealing out all of the polluted air unless they strap their masks very tight. They still report a large difference in clear airways compared to not wearing a mask. They say that their air consumption quality drastically improves while wearing their masks in traffic. Beards on the jawline or goatees on the chin are located right at the edge of the filter and may hamper a seal, whereas a mustache will not affect the edges of the filter.