Having the right gear in cold weather can be literally life-saving, just like wearing the right masks to protect from airborne pathogens. Most of us know a lot more about masks than we have in the past due to the ongoing global pandemic, but it might not be totally clear how or even if warmth and safety can be combined.
Let’s take a look at the different shapes and materials available in winter facemasks and how to pick the right combination to get a mask or masks that serve all of your needs.
Form follows function
The purpose of any face covering is to make a breathing space around your nose and mouth that is clean and climate controlled, just like any indoor space. There needs to be a free enough exchange of air for moisture to stay balanced and for carbon dioxide to leave, but not so free that warm leaves or, in the case of protective masks, too many pathogens can enter. How a mask fits snug to our head and over our face has a significant impact on how well it can control the microclimate around your nose and mouth.
Cold weather shapes
Half-masks are the simplest mask and the minimum possible size to protect the nose and mouth, so are best for protective masks. They usually have loops that go around the ears or neck and head to hold it in place. They are very easy to make, wash, and store in a pocket or bag.
The next step is a gaiter – a loose garment that fits tight around the back of the head under the ears and stretches to grip sung over the bridge of the nose. It’s warmer than a half-mask because it covers the neck as well. These may also be referred to as Buffs or tubes. Buff is actually the company that first popularized gaiters for cold weather, in an example of a generic trademark like xerox, many just refer to gaiters as “buffs”.
A balaclava or a ski mask is the final step and fits tightly over the whole head and neck. They may have three holes for the eyes and mouth, or just a wide hole across both eyes. The wide-hole version can usually be pulled down over the chin to expose the nose and mouth if necessary, and many are designed specifically for this with stretch fabric or a facepiece that folds down easily.
A winter face covering may also be assisted by clothing that covers more of the head. Scarves and other garments can drape over the neck to keep in heat. A lot of heat can be lost through the top of the head, so a beanie or other warm hat often completes the warm weather gear set.
Show us what you’re made of
There are many different materials that could be used to make a decent facemask, and a few that should be avoided at all costs. Let’s start with masks for cold weather.
Facemasks for cold weather
Protection from the cold weather generally involves three layers: moisture wicking, insulation, and protection, and it’s no different for your face. Moisture wicking clothing is usually the bottom layer, and moves sweat away from the skin. The insulating layer is in the middle, and is typically puffy with air pockets. The outside layer is usually thin and serves to block wind and rain. The outer layer is usually less breathable so it’s generally better for jackets and not masks. Here’s how to think about the different cold weather fabrics available:
- Cotton kills. Moisture loves to ruin cotton’s ability to function as a protective material. Any cold weather enthusiast will tell you that cotton should absolutely not be relied on to keep you warm. Cotton is the opposite of moisture-wicking, it both quickly absorbs water in tiny spaces and can bond to water chemically, which in turn makes it both quickly wet and difficult to dry. If you have ever hung up blue jeans in humid weather you know cotton seems to never dry in certain climates. When wet clothing touches your skin, you lose heat 25 times faster, which makes even mildly cold weather uncomfortable in a mask and dangerous if all of your clothing has absorbed significant moisture.
- Rayon, viscose, tencel, lyocell, bamboo, silk, goose down and duck down can also kill. While not quite as dramatic as cotton, all of these materials also have interior spaces for water and can bond with it chemically. When wet they lose insulation potential.
- Synthetic or polar fleece insulates. Fleece can refer to wool from sheep or goats, but most cold-weather fleece garments are made from so-called polar fleece, which is synthetic and makes for good cold weather clothing. It is lightweight and holds in heat, but strong wind can cut through it without an outer layer. It isn’t the best for moisture-wicking and also will not work when wet, but fleece doesn’t hold onto water and dries easily.
- Polyester and polypropylene wick water. These synthetic fabrics can move moisture easily, and are often the go-to for a cheaper bottom layer.
- Wool also wicks water. Wool is a good moisture-wicking bottom layer. Merino wool from Merino sheep is probably the best wool because it is lighter and softer than regular wool and doesn’t retain body odor. However, it is more delicate than synthetics and may only last a few years.
- Nylon is breathable and waterproof. This fabric is rarely soft and can feel like plastic against the skin, but is usually a great outer layer. Nylon garments vary from water resistant to waterproof, and can also vary in their breathability. An outer nylon layer or a mask made of nylon is likely to better resist water and wind.
- Gore-tex is a forever chemical. This material was very popular as a moisture wick for many decades, and isn’t really a fabric but rather a membrane that doesn’t absorb water and lets it evaporate. Gore-tex is now available generically by the name expanded PTFE or polytetrafluoroethylene, and is the same substance used as non-stick teflon coating on cooking pans. PTFE itself is thought to be completely inert, but is also known as a “forever chemical” because the only known way to destroy it is with a lot of heat that releases very toxic and non-biodegradable byproducts. PTFE and these byproducts now pollute the entire world, and are in the blood of 98% of Americans. It’s not quite clear what the ultimate health impact will be, but these substances have been shown to harm animals and will continue to build up in our bodies. It might be best not to purchase any forever chemicals that will only see a few decades of usefulness at most.
The take home message
- If you expect to be sweating at all from walking or any other movement, a polyester or polypropylene bottom layer helps to wick moisture away from your face to keep it dry.
- To keep your face warm, polar fleece and wool are excellent insulators.
- If wind or precipitation is an issue, a nylon outer layer can help to protect from the elements.
- Wool is the only natural material that is good for cold weather, stay away from cotton or down because they fail completely when wet. Silk or synthetic silks like rayon are also useless for insulation when wet.
Masks for pathogens
There are many airborne pathogens, but viruses are the most pernicious because their small size can allow them to float around for hours before settling. By breathing through a mask, pathogenic particles in the air will stick to fibers in the mask instead of getting into your body. Materials that filter the air best are usually nonwoven, which means their fibers are arranged randomly instead of regular rows like woven fabric for clothing. Woven fabrics’ regularity means that holes may line up and allow for particles to pass through easily, which makes for a bad filter, though the CDC is clear that woven masks are still protective.
The only way to be sure a mask is effective for pathogen protection is if it is tested to one of the many international standards, which are testing methods agreed upon by industry and academic consensus. Let’s take a look at different types of masks, what standards to look for, and how to know if they are effective for blocking pathogens before they get into your body.
- Nonwoven filtering face masks are effective if they meet the standard. Often referred to as “respirators”, the common N95 masks made by American companies, KN95 masks made by Chinese companies, or FFP2 masks by European companies are designed to pass a specific test to show they remove at least 95% of test particles. To be sure you are getting a certified mask, look for the name of the testing standard on the package. N95s will say they are certified by NIOSH (The National Institute for Occupational Safety and Health), KN95s will have the Chinese standard GB 2626printed on the package, and FFP2 packages will state they meet the European standard EN 149.
Keep in mind that the country of manufacture is not related to the standard. A mask made in China that passes the NIOSH test is the same as a mask made in America that passes the same test.
While they may provide some insulation, respirators or filtering-only masks are not designed for cold weather and do not filter when wet.
- Woven face coverings that insulate are also effective if they meet the standard. The ASTM (American Society for Testing and Materials) publishes the testing methods that NIOSH uses to certify facemasks. Any mask can be tested, not just the filtering-only masks described above, so you may find ski or snowboarding masks mentioning ASTM or ASTM F3502 in their marketing or on packaging. These masks have been tested to remove 95% of test particles.
- Surgical masks meet the standards. Though they appear to fit loosely, the FDA ensures surgical masks meet international standards. Look for the American standard ASTM F2100, the European standard EN 14683, or the Chinese standard YY 0469. These standards vary in many ways, but all require at least a 95% capture rate of fine particles (3 microns in diameter). The ASTM standard is the most stringent, however, and also requires a 98% capture rate of ultrafine particles (0.1 microns in diameter).
- Fabrics that are not filters can still filter. The CDC recommends using cloth masks for protection from airborne pathogens, but refrain from naming a specific fabric that works best. This is likely because scientists have been finding very wide ranges of filtration efficiency for cloth masks, one study found a minimum of 26% and a max of 80% for the cloth masks they tested. This is certainly less than the 95% for international standards, but even that 26% is better than nothing.
The CDC does recommend cloth masks with fabric that is comfortable to breathe through and has multiple layers that block light when held up to a bright source. One study found the most effective combination to be two tightly woven outer flexible layers and one inner nonwoven filtration layer.
Interestingly, even though cotton is bad for cold weather, it has an irregular fiber arrangement which more than one study has shown makes it effective for capturing particles.
The take home message
- Filtering face masks like N95s or surgical masks are the most effective and have been tested to meet specific standards.
- Any mask can be certified by ASTM testing as effective pathogen protection.
- It may be impossible to know how effective other fabrics are, but wearing any mask is better than wearing no mask.
- Any cloth used for a mask should not make breathing difficult and should block light. Cotton can be an effective inner layer.
You are the most important part of your mask
All of the testing standards mentioned above are missing a key element- the person who wears the mask. Airflow follows the path of least resistance, so a gap will let a lot of unfiltered air in and out. One study found that adjusting the fit of a woven cloth mask can as much as double its effectiveness, from 40% to 80%. At this point there are a wide variety of manufactured face masks out there that have well-engineered straps that tighten well and easily. Still, there are a few main points to consider when making a mask as protective as possible.
How to wear a mask
- Fit it over your nose, mouth, and chin. Neither your nose or chin should be exposed if the mask fits properly.
- The mask should fit snug against the cheeks. If the mask moves in and out with each inhale and exhale, it fits well. If it feels like air is blasting past your cheeks, try knotting the loops so it is tighter.
- Have a nose wire. Good masks have a piece of metal that goes over the bridge of the nose, which should be pinched or shaped to fit snug. If a mask doesn’t have a wire, but does have a seam across the nose, an unfolded paper clip pushed into the seam serves as an excellent nose wire.
- Wash your cloth mask at the end of the day. Cloth does not filter when wet, so be sure it dries before use.
How not to wear a mask
- Loose masks do not work. If a mask slips beneath the nose or allows air to pass the cheeks or chin, it is not protecting you or those around you.
- Valves let out moisture and pathogens. Some respirators have valves that open with each exhale. These are designed for day-long use by workers to minimize their exposure to dust or particles in the work environment, and valve serves to exhaust excess moisture. These valves can let pathogens out or in and are not ideal for pathogen protection.
- Wet or dirty masks do not work. A mask soiled with oils, moisture, or anything else may not pass air properly, which can impair breathing or cause unfiltered air to burst in from gaps.
- Beards do not filter. The average N95 or half mask does not work well or at all with a beard. This is an unfortunate fact, particularly for the author of this article. A mask cannot seal against the cheeks if it is pushed away by beard hair. Those of us with facial hair should trim it short as fashionable and seek out larger masks that can seal against the neck under our beards and back by the ears.
How to stay warm and uninfected
The best winter mask for you is obviously going to depend on how cold you plan to get, what degree of pathogens you plan to be exposed to, and how much either of those two will impact your health and wellbeing.
Option 1 : Warm with a chance of infection
If you want to stay warm but won’t be anywhere that presents a huge risk of an infection that upends your life, any simple half-mask mask made of merino wool or polar fleece will reliably keep your face warm.
Colder climates will require something to cover the top of the head and neck. A gaiter to cover the neck or a balaclava to cover both head and neck can help, as can additional clothing like hats and scarves.
If you plan to sweat, polar fleece will both wick and dry better.
If there is wind or precipitation, a nylon mask or added nylon layer can block the elements.
Option 2 : Warm and blocking the worst of the pathogens
Breathing through a fabric can make it more difficult for a virus particle to get to you, with tighter weaves offering more protection. As a general rule, fabrics that block light have a tight enough weave to offer at least basic pathogen protection, and many warm weather clothing materials meet this definition.
Masks labeled as tested by ASTM may be more reliable as pathogen protection.
Make sure the mask fits tight around your cheeks, chin, and nose.
Option 3 : Warm with the most pathogen protection
Wear two masks because there is no one mask that can be relied on to keep you warm and safe in all circumstances. An inner half mask that is ideally non-cotton but still tested to be effective is the best pathogen protection. This can be paired with the appropriate warm weather garment that fits loosely over the tight-fitting mask. A top layer to block wind and water may be necessary.
Option 4: Cold but not sick
It is always an option to use only a protective mask. Such a mask should never be wet, needs to seal tightly, and for maximum protection should be tested by a standards organization. Then you can try the following ways to stay warm that do not involve clothing.
Keep in motion, but not so much that you sweat, which will cool you down.
Drink water, dehydration reduces blood flow which you need to stay warm.
Drink a warm beverage so your body doesn’t have to work as hard.
Do not drink alcohol. Our body reduces blood flow in the fingers, hands, and feet when it is cold because a lot of heat exits through the palms, fingers, and bottom of the feet. Your body would much rather lose a toe to frostbite than freeze to death. Alcohol counteracts this survival mechanism and dilates the capillaries in the hands and feet, which makes them feel warmer. As a result more heat will be lost through the limbs and your core temperature will drop more quickly.
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