It may be stylish to wear a scarf, gaiter, or bandana in place of a mask, when it comes to protection, face coverings are not created equal. Here’s what you need to know.

Medical grade masks are designed specifically to protect the wearer from airborne and liquid contaminants. They contain layers that repel water droplets and filter out bacterial and viral particles. Cloth masks don’t have these specialized layers, but good ones will have three or more layers made of cotton fabric to help catch particles, and the best ones have pockets for replaceable polypropylene filters.

Improvised fabric face coverings such as scarves, bandanas, and neck gaiters offer almost no protection against transmission of respiratory droplets. A study by Duke University even found that neck gaiters let through more droplets than wearing no face covering at all, because the thin fabric disperses larger droplets into smaller ones with a heightened ability to remain airborne. This creates a larger exposure risk especially in narrow or crowded settings like hallways, crowded streets, and subway cars. Bandanas are not suitable as they leave huge gaps under the mouth for particles to travel out as you speak, breathe, or sneeze.

If for some reason you don’t have immediate access to a mask, any face covering is preferable to none at all. Be sure to use thick fabric or fold your fabric into multiple layers, and try to create the tightest fit you can. Always make sure that your mask or face covering covers both your mouth AND nose.