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What is Cold Weather Induced Asthma?

Twenty below zero on a winter hike

I vividly remember the first time I experienced cold weather-induced asthma. It was the same day my camera froze. It was 20 degrees below zero and we were climbing two mountains in New Hampshire’s Pemigewasset Wilderness. I remember a tightness in my chest and shortness of breath. We got down ok, but I carried an inhaler for a few years after that and avoid really cold weather hikes to this day.

While cold-induced asthma shares the same symptoms as chronic asthma, it’s not a chronic condition but one that is induced by exercising in cold dry weather. Called exercise-induced bronchospasm, it can be triggered during periods of heavy exertion (like climbing mountains) when people tend to breathe through their mouth instead of their nose.

Mouth breathing brings cold and dry air directly into the lungs, without the warming and moistening effect that nose breathing provides. As a result, the air is moistened to only 60-70% relative humidity, while nose-breathing warms and saturates air to about 80 to 90% humidity (Source: Mayo Clinic).

Covering your mouth can help mitigate the effect of inhaling cold dry air since an insulated buff or face mask will trap warm moist air close to your face. Breathing through a Cold Avenger Face Mask can help warm and moisten cold weather inhalations. Using a prescription Albuterol inhaler can also help when used before your hike.

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  1. You’re lucky, mine kicks in at around 30 degrees. Hits me most when cycling in the cold .

  2. As a registered respiratory therapist, I can state that breathing cold air in and of itself does not cause an asthmatic attack. Mayo’s statement is an overly broad generalization. The human respiratory system is so efficient at warming air, that even when breathing strenuously, cold air is at body temperature by the time it reaches the main bronchus regardless of whether a person is nose or mouth breathing. There are many studies in the literature about this.
    Nose breathing more efficiently filters out particulates that might precipitate an attack than mouth breathing because the small hair-like fibers in the nose and the increased moisture trap more particulates than mouth breathing.
    When a person engages in strenuous activity and so likely to be mouth breathing, far more particulates can be introduced into the lungs, resulting in an attack. So it’s the increased particulate deposition not cold air that is the cause.

    • What kind of particulates would induce this in the middle of a wilderness area in subzero cold? The air Is as pure as it gets and I never experience this condition in any other time of year.

      • Being in the wilderness does not mean there aren’t particulates in the air because there are particulates no matter where you go. Just look at the top of the snow after there hasn’t been a recent snowfall and you will see it is covered with tiny bits of debris. In the spring when snow is melting fast the top of the snow is filthy. That’s the stuff you are breathing in. The colder the air the drier the air, so the less efficient is your respiratory system at removing them because moisture helps trap the particles before you breath them in. As a respiratory therapist who has treated thousands of patients and read hundreds of articles, I can tell you that cold air in and of itself does not trigger an asthmatic attack. I’m not saying that you don’t have more trouble breathing heavily through your mouth in the cold, I’m saying I’m trying to explain why you inhale more particulates under that circumstance than you would when it’s warmer.

        • I have exercise induced asthma and when I mouth breathe, no matter what the temp -hot, cold or in between- I have trouble breathing. In winter, I try to breathe exclusively through my nose and certainly use a face mask to help warm the air going in. It is also important to carry one’s “rescue inhaler” on an inside pocket in the winter and to let the hike leaders know where it is. In fact, it is a good idea to bring two, in case one of them freezes up. My doc advised using the albuterol one half hour before strenuous exercise, then putting it in a pocket next to the body. Yes, I’ve noticed all the crap that blows through the woods and lands on the snow. One day after a snowfall and the snow in my wooded lot looks pretty dirty.

  3. I don’t have asthma but definitely notice a difference doing strenuous activity outside in colder weather. Thanks for sharing the article!

  4. I wear a balaclava when exercising in cold, dry weather. It cuts the wheezing to zero. I have wondered whether that is because the fabric warms or strains the air. Don’t care too much, though. It works.

  5. Here’s an interesting article reviewing the different mechanisms:
    Regardless of the underlying physiology, sounds like you’re doing the right things!

    • Yeah, but that paper is dated in 2007. It is a good overview however.

      Sounds like doctors keep changing their minds about this (using us as guinea pigs). Don’t get wrong. I love science. But my dad was an MD and I quickly learned that medicine is more an art than science.

  6. I like that one Philip, art has served me well while hiking

  7. Rescue inhaler on hand is a critical thing to remember for those who have kids/significant others with asthma, if planning an outdoors or an international trip. Good reminder post.

  8. I’ve never been diagnosed, but have had incidents where I felt like I’ve had exercised induced asthma. It seems so random and rare it is strange. I went hiking in Iceland, and one day after hiking 1/4 mile felt like I couldn’t breathe. It was the super scary, as I have never felt that way before. I figured there must be something in the air there that bothered me. I have had it on occasion since then, but actually during warm weather. I’ve been experimenting with trail running – so lots of mouth breathing. Sometimes this triggers it. When it happens, I switch to walking. It just seems very strange as it isn’t a consistent thing. How do they test for this?

    • Hi, Agile Trekker. Your symptoms sound just like mine before I was diagnosed with exercise-induced asthma. Talk with your doc or get referral to an asthma specialist to get a definitive diagnosis, and importantly, the medication you may need so that you don’t have a more serious incident. I hate to bring this up, but asthma can disable you. My cousin, who was a “severe” asthmatic, was killed by it while driving in smog-encased, stop and go traffic. Exercise -induced asthma is much more manageable, but scary nonetheless. Thanks very much to Philip for making this a topic on the blogsite.

  9. Cold induced asthma is similar to exercise induced asthma (which can occur in warm environments). The temperature of the airways probably triggers the bronchospasm to occur in susceptible individuals. Treatment with the rescue (beta stimulant) inhaler prior to exercise or cold exposure can prevent the attack.

  10. I use a Lungplus and it works well. Basically same function as the Cold Avenger but easier to take with you in a pocket.

    You don’t look that cool though :)

  11. Being in good shape seems to help too. I have exercised-induced asthma as well and in winters when I am in good shape the inhalers help to the point where I don’t have an issue. However, this past winter I was in lousy shape, went on a short but steep hike in 11-degree weather, and then proceeded to cough for at least six hours after the hike was over.

    I am planning to be in better shape this winter so this is not an issue. Hiking is more fun when you’re in better shape anyway. :-)

  12. I’m a rural carrier mailman and I wonder if this is what I have experienced a few times. It seems to occur on cold or raw days where i’m driving around all day with the window open and on a particularly stressful or high exertion day on a unfamiliar route where maybe i’m mouth breathing more. I usually cough more randomly and get a weird “full” or heavy feeling in my chest or lungs. It usually dissipates soon after or by the next day and doesn’t always happen. At first I thought maybe I had bronchitis or walking pneumonia but went to walk in clinic and nothing was found

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