B2 Mask in a puddle


Here in Minneapolis, like many other northern parts of the world, the temperatures have dipped below freezing. Given the state of the Covid-19 pandemic as we write this in early December, the CDC still advises wearing face coverings when it’s necessary to go out in public. Unfortunately, the combination of cold weather and humid breath results in foggy glasses and soggy masks! 

As such, we’ve done a lot of thinking at Breathe99 about why excessive moisture builds up inside of a mask and what can be done about it. Here’s a look into the science, and what you can do to mitigate the effects of moisture buildup inside of your mask. 


Why does my mask get wet?

Cold Weather

Ever worn a scarf across your face in the winter, to find that it gets soaked after only a few breaths? This is because cold air holds less moisture than hot air. Your warm breath has way too much water for the cold air, so it condenses on whatever surface you breathe on— especially the inside of a mask. This tipping point of condensation is called dewpoint*.

* To see the relationship between air temperature, dewpoint, and relative humidity, check out this sweet graph.

Hot Weather

This one is more straightforward - when it’s hot, you sweat! Your skin radiates heat and sweats, plus your breath is already humid. The moisture is created much faster than it can evaporate. 


So what can I do?

We can’t cancel winter or summer. We can’t change our humid breath. And a mask must remain well-sealed for protection (this is also why the B2 Mask doesn’t have exhalation valves). So keeping public health guidelines in mind, here’s what you should know.

Wearing a mask indoors is not so bad

In a temperature-controlled indoor environment you don’t have the extreme heat or cold that causes extra moisture buildup. Most of the moisture in your breath will escape through the filters of your mask. 

Limit the situations in which you need to wear a mask

The CDC recommends wearing a mask in "public settings where other social distancing measures are difficult to maintain," which includes most public settings for shopping, eating, and entertainment. Is it necessary? Read the CDC guidelines on deciding when to go out (or stay in).

Take breaks to dry your mask

If you need to wear a mask for a long time, try to work in a break where you are in a socially distanced setting and able to clean your hands and remove your mask. For example, a well-ventilated washroom or breakroom, your car, or an outdoor space. Masks like the B2 allow you to wipe the inside of the mask dry with a clean paper towel. Fabric masks will not dry out quickly, but you can keep multiple dry and clean ones on-hand.

Be kind to your skin

Another reason to take breaks and remove your mask is so that your skin can get relief from the humidity. The American Academy of Dermatology Association recommends that healthcare workers take a 15 minute break every 4 hours, among other tips to save your skin. Avoid wearing makeup under your mask and apply a non-pore-blocking moisturizer once you’re able to remove your mask. 

What about anti-fog coatings? 

Unfortunately they are no match for the extreme temperature and humidity of cold or hot weather. Anyone who has worked up a sweat wearing anti-fog goggles or sunglasses will tell you that the anti-fog effect is lost in extreme conditions.  

Absorbent ideas

If you wear a mask like B2, then placing something absorbent inside the mask does help collect excess moisture. Many household spongey materials work well, particularly absorbent foam pads or cloths. Just cut to size, and wash or throw out after use. 

Edit Jan 2021: We now sell a foam liner made specifically for our mask, called the B2 Mask Liner. It's made of ultra-absorbent reusable Aquazone foam. 

Stay protected, stay kind

If you have made it this far, you probably care deeply about following public health guidelines, whether for your own protection or for that of loved ones. Remember that staying protected isn’t simply about wearing a mask all the time, it’s about understanding the most important times to wear a mask, and when it’s safe to take a break. 

As we’ve heard from many B2 Mask users, we are in a challenging and emotional time. Amidst the fatigue and frustration, our last tip is that a little bit of kindness and empathy goes a long way in staying healthy together <3

Did you find this useful?

Questions or comments? Reach out to hello@breathe99.com