Posted on 45 Comments

Heat Exchanger Masks – a Love Story

(updated, February 2024)

How I Started Caring About Heat Exchanger Masks

Back in the 90s I started riding my bike to work after a hiatus of a few years. My coworkers would regularly ask me if I was going to be like Tom, a notoriously all-weather rider. As winter came on, I realized what most people who cycle in the winter do, it isn’t as hard as it looks. It can, however, be cold. With the internet in its infancy, it wasn’t easy to find quality information on how to stay warm in winter, but I knew at the time that my airways were a weak point in that I couldn’t really insulate them from the cold air that passed over them. Then I read about a product called LungPlus and my obsession with heat exchanger masks began.

I have lots of experience in the cold, and I understand that breathing cold air is probably not going to kill me. But, anything I can do to make myself more comfortable in the cold is a good idea. Breathing warm, humid air at -40º is comfortable, so I’ll do it. I don’t care if other folks are tougher than me.

The Untold Story

The human body is remarkably good at keeping itself heated. The circulatory system will gradually move blood flow away from the surface and away from extremities to keep its vital organs warm. Activity, including shivering, will help by generating heat. But in order to do any sort of activity, one needs to breathe, and in the cold, that means breathing cold air.

The air passages are designed to warm up air as it enters the body so that the blood can pick up oxygen from it. Unfortunately, this is exactly the same as wind chill. On top of that, the airways are damp, which means they are subject to evaporative cooling just the same as if a person was to go outside still damp after a shower. Except that the lungs have approximately 5 times the surface area of skin, and they are always naked.

Well, What the Heck am I Supposed to do About it?

If you stop breathing you will die.

The simplest form of heat retention is the extended hood that Northern peoples have used for millennia. It creates a pocket of warm air around the person’s face, and helps take the edge off breathing in extremely cold air. In turn, this pocket of warm air requires less warming by the airways and lungs and so is pulling less heat from the body.

The next low-tech solution is the scarf, Buff, mask, or bandana across the face. These do capture some heat from the outgoing breath to warm the incoming air, but their primary purpose is to warm the face itself. They are great for preventing frostbite on the face, but they do relatively little to prevent heat loss through breathing.

The next technological step is to use a heat retention or heat exchange device to capture the heat from outgoing air and return it to the incoming air, and that is what this article is about.

Yes, 8 Heat Exchanger Masks!

(and more on the way)

from top right: Airtrim, Polar Wrap, Psolar, Ergodyne 6970, and Lungplus with a modified face mask. (5 masks)

What follows is a brief description and mini-review of the 6 heat exchanger devices that I personally own. Yes, I could have gotten away without buying more of them, but in my efforts to optimize, I have continued to purchase more.


This device is the only one on this list that does not have a mask with it. It was the first one that I used back in ’99 or ’00. The device is a bit like the mouthpiece of a snorkel with a heat exchanger built in to it. It isn’t fashionable, or really even dignified, but it does work. This is the device I used on the ITI in 2002


  • It helps keep glasses unfogged by routing breath away from the eyes.
  • It is an effective heat exchanger and helps to keep the body warm
  • it routes the captured water away from my chin and reduces beardcicles.
  • It is compact for carrying in a pocket or bag
  • it is nearly indestructible


  • Looks like a science fiction device worn by Venutians to breathe the earth’s poisonous oxygen.
  • It routes air through the mouth and I find it sometimes makes my teeth cooler
  • droolcicles at the end

Polar Wrap

Oh yeah, this device lets you breath warmer-than-room temperature air. Oh damn, when I exercise it is like breathing through a straw. This is the best device for waiting for the bus.


  • fit is adjustable
  • Warm, warm, warm
  • Oh, so very warm


  • Very restricted breathing, not suitable for any activity.


This device is great, if they still made them, I’d have bought more.


  • great heat exchanger
  • close fit to the face
  • low profile balaclava works well with other hats
  • very free breathing and the air path does not ice up


  • the exchanger sits close to the lips and can contribute to chapped lips
  • the exchanger forms a shelf that can collect snot
  • they were bought by another company and were discontinued

Cold Avenger

This unit is a little more sophisticated than a long hood on a parka, but not much.


  • Simple, never clogs
  • keeps the mouth and nose clear so skin stays un-chapped.


  • no real heat exchange, only a pocket of exhaled breath at the mouth
  • some (Tadhg) find it restricts breathing
Cold Avenger Mask
Cold Avanger on a cold day.

Ergodyne 6970

I bought this one based on a review from a friend with more cold weather experience than me (yes, those people exist).


  • Very effective heat exchanger
  • good airflow for high-output activity
  • keeps wet parts off the face
  • the “Darth Vader” look
  • great balaclava


  • does eventually get somewhat wet
  • the “Darth Vader” look
  • the great balaclava is a bit tight on my enormous head


Airtrim Heat Exchanger Mask

This and the Ergodyne are my go-to masks for cooler days. Back to back testing today gives the edge to the AirTrim for warmth.


  • Warm
  • doesn’t restrict breathing
  • away from the mouth and nose for reduced chapping
  • doesn’t put pressure on the nose – less runny nose
  • is available with a selection of exchangers with greater flow, or warmer air depending on activity


  • Recently, a grade 2 kid said it looked like a pig nose
  • it does not cover the upper cheeks – risk of frostbite
  • if you neglect to blow the water out of it the water can drip on clothing

Naroo Z9H

Finally a recommendation

On the bike, and this is at least partly a blog about bikes, the Ergodydne (associate link) has the edge because of its coverage of the cheeks. However, if you have or can get a face mask that covers the cheeks and leaves the mouth and nose free, the AirTrim’s superior performance will win out. All this week, I was outside in temperatures as low as -29ºC with the AirTrim on, and I dressed exactly the same as I would have for -12ºC without the AirTrim (yes, it is that good). I now get a commission if you buy it through this Amazon Associate Link to the Airtrim Sport, though I’d still be grateful if the good folks at AirTrim were to send me 3 more for the rest of my family, (hint, hint). I bought my AirTrim from

Below -25ºC roughly 90% of a body’s heat is lost through respiration. if you could reduce even 15% of that it would be equivalent to doubling your clothes. When you keep your core warmer, it signals the brain to send more blood to your extremities, so in a way, the heat exchanger mask is a handwarmer too. Not that I want to discourage you from buying a pair of the pogies I make by hand.

Paolar is no longer available.
Yes, that thermometer reading below its -30ºC lower limit.

What About Medical Benefits?

We’ve all heard about the dangers to lungs and airways of breathing extremely cold air. I am not a physician, nor do I play one on TV. I am way too lazy to do the research as to what medical benefits these masks may give to users. Even if it were no medical benefit, I would still use one for comfort and for warmth. Airtrim and Lungplus have some medical articles on their sites that I have not read.

Updated testing (January 2023)

February 2021: At -25ºC, I have now done some more objective testing with my 3 favourite (and available) heat exchangers. After 5 minutes outside, breathing through my mouth, I measured the air temperature inside my mouth. The Airtrim Asthma filter was warmest (12º), Then the Ergodyne (10º), then the Airtrim Sport (9ª), followed by the AirTrim racing filter (7º), and finally the Lungplus (5º). For reference, I measured using a blue surgical-style mask (-5º), and no mask at all -10º). The blue surgical mask was way better than nothing at all, a full 5º warmer, but the remaining masks were another 10-17º warmer. I did not do anything more strenuous than walk in a circle for this test, and results could be different for exercise.

Feb 10: further testing, since some people have recently questioned me about the Cold Avenger, I measured, and it performs somewhat worse than a buff or blue surgical mask. The Cold Avenger balaclava is very warm, and for those mostly looking to keep moist cloth off their face and have a balaclava, it may be a good choice.

January 2023: I added in the two Naroo masks

The Road Ahead (January 2024)

I now have 3 prototype masks from a new manufacturer, they check a lot of awesomeness boxes. Though they are a little heavy, they block a lot of fog from my goggles, they are very nearly indestructible, and they work really well.


Lungplus sent me free product in about 2000 with no conditions attached. I have purchased all the other products myself with my money. At the time I am writing this, I derive no benefit from sales of any of these devices. edit: I now have an amazon associate link for the Ergodyne 6970. I have received no money for this review, but I won’t turn down offers of free product. Edit: I also now have this Amazon Associate Link for the Airtrim Mask.

2024 I paid nothing for the prototype masks that were sent to me.

Naroo sent me both the masks here for review, and I tried them in appropriate weather for each of the two models.

45 thoughts on “Heat Exchanger Masks – a Love Story

  1. From one human to another, I would like to sincerely thank you for this post. Although I live in the desert, the AirTrim mask has greatly helped me while cycling in our extremely dry climate. I wouldn’t have come across this particular heat exchange mask if it weren’t for your website and your stellar review prompted me to purchase the AirTrim and give it a shot. For this I am truly grateful. Thank you!

    1. I would not have guessed that the AirTrim would work in the desert. Thanks for letting me know.

      1. Can you wear Airtrim in the rain?

        1. I assume so, I only wear it when it gets cold, (below -20ºC) and it works better with larger differences in temperature between you and the air, but otherwise, it should be fine.

      2. The Lungplus would work in the desert and is great for climbing in altitude because it humidifies and heats the air. You would get very warm if you use it in the desert. I used mine when I had bronchitis the one time in my life and it humidified and helped with my cough.

      3. Just bought one of the air trim normally never worry about cold air live in northern Alberta I got Covid bad in ICU Vent ect couldn’t get outside for anything cold just killing my lungs start getting fluid again ect found your research on masks went with advice for this one it’s been -25 to -42 up here got farm with chores got mask in mail today gave it a spin works amazing-25 outside out moving bales for half hour as far as lungs go didn’t even know was cold outside Thank you for your advice

        1. Thanks, it makes me very glad to hear that I helped

  2. Which is best for running or HIIT?

    1. Probably the AirTrim with one of the sportier elements. Even the more restrictive elements are pretty free-flowing. I don’t really notice the restriction, even when pushing myself, and I do notice it on some of the others. The Lungplus could probably work, but I would be worried about injury if one were to trip.

      1. You just spit the lungplus out…if you are using it with a string around your neck that works great. The string collects the drool too. Teeth should not be getting cold if you are using it correctly.

  3. Native Wisconsinite here, thanks for the post.
    Two thoughts:
    1) I’ve worked or ran outside in air so cold my eyelashes had icicles, never in my life have I heard of cold air being “bad” for you.. makes me laugh. Maybe its just in my genes.
    2) One thing you never mentioned is its use for hunting! Sitting in a tree stand in -10F (not including wind) gets chilly in a hurry, so my primary motivation is to make those days suck less.
    also…where can I buy a psolar…

    1. If I was sitting in a hunting blind, I’d look for a Polar Wrap. It is ridiculously warm. The Psolar got bought out and discontinued.
      As to your first statement, I tend to agree, except that I get a pretty dry throat if I’m out in anything below -30ºC for long. I more use the masks for keeping the rest of me warm. I never count wind chill.

  4. Hi!
    To what extent does the “LungPlus” heat the air?
    I mean, the cool -15°C is were I no longer run because of the cold air. How much lower could I go with one of those?
    I don’t semn to find a conclusive answer…

    1. I haven’t done any objective measuring, but it feels like about 10º-15ºC. It is very effective for its small size, but I feel the newer devices like the Airtrim are an improvement over the Lungplus.
      The Airtrim with a sport filter is warmer (I would estimate 25ºC over ambient, maybe warmer) and less intrusive since you don’t have the snorkel bit in your mouth.

      1. The Lungplus is just as warm as the airtrim, actually it would be warmer if you cut the hole in the buff and put it through because your face is dry. If you are using the Lungplus correctly, you won’t notice it is in there…it just hangs.

        1. I have a buff with a larger hole for the airtrim, and a couple of masks and a buff for the lungplus. I cannot take the temperature of my lung air, but my mouth is measurably colder with the lungplus than the AirTrim or Ergodyne (I measured yesterday when it finally dropped below -25ºC), not that I consider the lungplus to be bad, it is simply the second or third in my personal ranking of these devices. It could be that my face isn’t the right shape for the lungplus to work well, but I have used it for hundreds of hours, it is good, it just isn’t as good for me while cycling as others. Keep in mind that I use these devices for long stretches of up to 16 hours per day for consecutive days, so my information may not be as valid for shorter times.
          In my experience, the Lungplus is too wide to spit out quickly, and too narrow to hang in my mouth when I am relaxed. It also does not work if I breathe through my nose, which I sometimes like to do. I’m not saying it’s bad, just not as good as what I like best. Lately, I have been finding the compact shape, and nearly indestructible nature of the LungPlus to be a huge benefit to packing it in my bike bags.
          If you feel that my experience is not good enough, feel free to write me with a direct comparison, including at least 30 hours of use below -25ºC of each device, and I will add it to my article.

    2. The Lung plus if used correctly will heat your entire body and your lungs without fogging up your glasses or your face. I like it much better than the face mask types, like the air trim because the snot doesn’t pool, your face stays dry, and your glasses won’t fog. If it is really cold you can cut a hole in a buff and put that around your face…it will keep it warm and your face will stay dry. I ski in mine until it is -60 windchill and -25 air temp…just haven’t tried it when it was colder. I have had mine for 7 years and use it all winter.

  5. I’ve recently read Breath by James Nestor. The main theme of the book is that it’s way healthier to nose breath. I’m wondering how the exchangers work with nose breathing.

    1. There could be some restriction of the nasal passages from the masks, but it is relatively minor. I like to breathe through my nose, and have no trouble with the AirTrim or the Ergodyne. The Lungplus is a mouth-only device.

  6. Thank you for this excellent article. It’s not easy to find good information on these kinds of breathing solutions.

  7. Great article.

    Would you also know if these masks can cause medical issues long term? I think breathing through plastic is maybe not so good, as you would perhaps breathe in plastic particles as the mask wears down which would go directly into your lungs. Just a thought!

    1. That is a legitimate concern, and I don’t have the full answer, but since the plastic has moisture from the breath coating it, the airborne plastic particulate should be minimized. Using the Airtrim, I find the smells from other particulates, such as diesel exhaust is reduced, so it may actually be helping.

  8. I use Jonasport (made in Finland, metallic) while running in the cold. These breath-warmer devices are awesome! I noticed all the same things, usually I wear too much when using the warmer.

    1. That looks like a pretty good one, though I cannot find the manufacturer site or a North American distributor. If you have one, feel free to forward it to me.

  9. I bought two Air Trim masks from you.
    What are they made out of?

    1. I don’t actually sell them, I only provide the links to Amzon, who pay me a commission, and, who seem like nice folks. I am honestly not sure what they are made of, other than the obvious that they are some kind of foam.

      1. I am working on prototype of my game changing mask. Would you be interested in testing it?

        1. Yes, I’m always interested in new products, and while my recommendations stand, there is always room for improvement.

  10. I certainly would… the Air Trim seems fragile for my fat biking.

    1. I have put several hundred hours on mine, and though I have accidentally stepped on it and crashed several times, it has held up so far.

  11. Hi Doug:
    Three years ago I lost 25% of my lung capacity to a rare disease called Sarcoidosis. In a matter of months I went from being an active skier, biker and paddler, to a shut in, who could not push his own lawnmower across the yard. My lockdown started a year before Covid19 changed everyone’s lives. I had tried the early versions of the Airtrim when I trained in Canmore but was quickly laughed off the trail by my macho team mates. Fast forward to 2019 and not being able to handle outside air below freezing temps. I tried many air exchanger ideas but none were ideal. By trial and error I have discovered what you have shared, and reclaimed my right to walk the dog and spend more time outside in the winter. The Airtrim asthma filter extended my air temps from 0 degrees to -15 degrees Celcius and when worn with a traditional fur trimmed snorkle parka, I could handle as much as 30 minutes walk at -25 C ! This was a game changer for me in the last two years… being housebound in the winter months is a thing of the past. No one looks twice as masks are everywhere. If you find a better product, let me know and I will gladly test it.

    1. Thanks so much for sharing your success story Brad. Congratulations on taking so much initiative to get yourself outside.

    2. I actually was given a gift card for being the only rider in a fat bike race to wear his mask the entire race, little did they know it wasn’t a Covid mask lol. I’m wearing the Breathwarmer now made in the states that works better for me since I pull mine down a lot and only use riding into the wind or breathing hard on hills. My Airtrim mask filter would pop out sometimes while pulling it down or back up. Also you might consider looking at Watercress capsules for breathing ailments, it’s helped me out a lot. I know in Europe they use it together with horseradish capsules but I’d rather eat that instead….

      1. Yes… the Air Trim is a bit fragile for active sports. I patiently re-seat the filter every day and wash it when I get home from my walk. I am a bit amazed after all this time that it has not fallen apart. I keep thinking that I will try a gentle adhesive to hold the filter in place…

        1. Looking for a mask that will keep breath warm. My guy friend has a broken neck and has plates and screws. His body gets painfully cold, so we need something to keep breath warm… will this or something else work. Lives in cold Minnesota

          1. The airtrim with the asthma filter is probably the best for keeping breath warm.

  12. What would you recommend for a glasses-wearer that would appreciate the option to nose breathe? Intended uses include XC skiing, fat biking, and running.

    1. I have a very sharp nose, so glasses and googles seem to fog no matter what I do. I know that many people have had great luck with the Airtrim.

    2. The Lungplus will work for that.

  13. What is the material of the heat exchanger insert in the Ergodyne?

    1. I haven’t a clue, my science has been limited to testing the functionality of these.

  14. I got the air trim but I can’t get it to fit, which surprised me as I have a small head and face. It sits really weird, not cupping my chin but sitting on top of it and not sitting on my nose right. The strap exacerbates the fit problems as well. I can hold it on my face with my hand in an ok position but when I use the strap it slips into a bad position again. I think I am going to return it and try the ergodyne instead

  15. Thanks for the writing of this post. Recently underwent lung surgery and had pneumonia and an empyema so the -5 and lower temps are a no go for my lung so I was trying to figure out what to do. Came across your post and I ordered the asthma air trim mask. I hope it allows me to walk the kids to their school doors and move about outside easier so I don’t have further health complications. Much Appreciated!

  16. One thing to note about the AirTrim at least (and probably others) is that they will freeze up a very low temperatures in higher winds (like riding a bicycle). We had a stretch of < -30C daytime high ambient temperatures here in Edmonton this year, and I found that I couldn't use it during my 20 minute bicycle commute to work because at about the 15 min mark it would be completely frozen and I had to remove it to breathe. I tried both different filters, over 3 separate cold rides and it happened every time. Keep this mind if you're planning extreme cold usecases.

    1. I am not sure why this is happening to you, I have used mine for entire days where the temperature stayed below -35ºC temperature. I do blow mine out occasionally, but have not had the freezing problem.

Leave a Reply