If your masks are beginning to feel as old as this pandemic, it’s probably time to get yourself some new ones.

The Centers for Disease Control and Prevention advises using masks that have at least two layers of tightly woven, washable, breathable fabric, such as cotton. When you wash your masks regularly, which you’re supposed to do, the fabric, as well as the fit, can begin to deteriorate. As this happens, your masks become less effective.

"A newer, fresher mask is likely to have tighter fibres, and so it’s likely better at keeping out other particles and keeping your particles in," says Krys Johnson, an epidemiologist and assistant professor at Temple University.

The exact timeline of when you need to replace a mask depends on the makeup of the mask, along with other factors like how much you’re washing it, and how often you’re taking it on and off.

But as a general rule of thumb: "Think about masks like seasonal attire. Update every season," says Johnson.

Here’s how else to know if you should replace a mask.

A snug fit is key. If the elastic of your ear loops starts to loosen, it’s time to reach for something tighter.

That’s a bad sign, says Johnson, and may indicate that the fabric is deteriorating, or was too thin from the start.

A mask needs to cover your nose and mouth in order to work. If one of the straps falls off and you have to keep touching your mask to keep it in place, this defeats its purpose.

This is perhaps the most obvious sign of all. If your mask is ripped, it needs to go. It doesn’t matter how small or large the hole is.

Experts strongly recommend owning more than one mask. And in the winter, you’ll want to carry a backup. Moving from chilly outdoor environments into cosy indoor settings makes it easy to sweat through your mask, as does wearing multiple layers. You’re advised to always swap a wet mask for a dry one. A wet mask can make it harder to breathe. And of course it’s uncomfortable, especially if you’re walking back outside into cold temps.

When in doubt, replace it, says Johnson. The focus is on eliminating risk as much as possible right now, and proper mask wearing is part of that.

If you have a disposable face mask, the CDC advises throwing it away after you’ve worn it once.

— The Philadelphia Inquirer