The Best Ways to Make Sure Your Face Mask Fits Correctly, According to a New Study

The fit of your face mask has a lot to do with how effective it is — the tighter the better for filtering your breath and keeping others safe from viral particles, including those of COVID-19. That said, it's not always easy to find a face mask that fits perfectly. While we all have our own tricks for ensuring a tighter, more comfortable fit (nose and mouth covered!), what does science have to say about the topic? Which DIY face-mask hacks are actually the most effective?

In a recent study published in "Plos One," a group of researchers from the University of Cambridge decided to find out. They tested seven different "fit hacks" on four different participants, asking the wearers to perform various tasks that mimicked daily activity — talking, smiling, nodding, turning their head from side to side, bending over, and breathing normally and heavily. At the same time, the researchers took air samples to determine the concentration of particles inside and outside the masks. The participants tested the hacks on two types of face masks: the highly effective KN95, and more loosely fitting surgical masks.

The fit hacks they tried out were:

  • Sealing the edges of the mask with cloth tape
  • Stuffing the gaps in the mask with first-aid gauze
  • Binding the mask to the face with a roll of first-aid gauze
  • Placing a cut segment of pantyhose over the head to seal the mask to the face
  • Knotting the ear loops of the mask
  • "Bracing" the mask with three rubber bands

For both types of masks, the pantyhose hack was the most effective at improving fit. Researchers calculated a "fit factor" score based on how efficient each hack was at filtering particles, and found that the pantyhose trick increased the fit factor by 27.2 for KN95 masks and by 7.2 for surgical masks. Taping over the mask came in second, improving fit factor by 14.7 and 4.8, respectively.

For the KN95 mask, the rest of the hacks offered only minimal improvement: wrapping gauze on top improved the fit factor by only 1.6, and tying the ear loops barely improved the fit factor (0.8) because KN95 masks already fit very tightly. For the surgical masks, the rubber band and ear-loop-tying tricks improved fit factor by 2.5, making them the least effective hacks — but still offering improvement over wearing an unaltered face mask.

The researchers noted that the most effective hacks were also the most uncomfortable, sometimes cutting off circulation or, with the pantyhose in particular, making it difficult to speak. The pantyhose also slipped up and covered the participants' eyes at some points. (The tape was "reported to be comfortable while worn," but sometimes painful to remove.) "Many of the most effective fit hacks were so uncomfortable as to be unusable in some cases," the researchers wrote.

However, these cheap and accessible tricks could improve your face-mask fit if you're concerned or nervous in certain high-risk situations, such as while traveling. In addition to helping people increase the effectiveness of their own masks, researchers also hoped their findings could help designers make more effective, better-fitting face masks.