When you step outside your house wearing a face mask while also wearing glasses, you may notice your breath sometimes flows upward and fogs them up.

It’s a common occurrence for many people, and a number of factors can cause it: from the weather to the quality and fit of your mask. There are a few ways you can prevent your glasses from fogging up while wearing a face mask.

Tighten the fit around your face

Your breath flowing upward could be a sign that your mask isn’t tight enough around the bridge of your nose. If you’re wearing a mask that has a metal band on the top, adjust it so it contours with your face.

If you’re wearing a cloth mask that’s adjustable, try tightening it.

With medical masks, like N95s, there should be little to no breath escaping, but the regular, cloth masks that the public has been advised to wear, some fogging up is normal.

Adjust the position of your mask and glasses

You can also lower where the mask sits on your face “so your exhale breath exhaust is a little bit lower. But don’t bring it too low because the mask should cover a majority of your nose and all of your mouth.

Remove your filter or try a thinner fabric

A lot of breath escaping and fogging up your glasses might mean that your mask doesn’t allow adequate airflow. If you’re using a filter, try one that allows more air to flow through. If your mask is homemade and you can remove a layer of fabric from it, try that.

To check if your mask is thick enough, hold it up to the light. If you can see individual fibers in the mask, then it’s probably not made of a good material.

Wash your glasses in soap and water

You can wash your glasses in soap and water. Let them air-dry to prevent fogging to avoiding leaving a protective film on the lenses. You can buy a commercial anti-fogging spray.