Ask The Advocates: Does Heat Have an Impact on Asthma?

Last updated: March 2022

Sometimes ones asthma gets worse when it's very hot outside. So we asked our advocate team of respiratory therapists and asthma educators the question, "does heat have an impact on asthma?" Here are their responses:

Does heat trigger asthma symptoms?

Response from Theresa Cannizzarro, Respiratory Therapist:

Heat is one of my biggest asthma triggers. Some asthmatics are effected more than others when it is hot outside. Generally, when it's warmer outside heat and sunlight combine with pollutants which can set off ones asthma. Heat with humidity can also be an asthma trigger. The moisture in the air makes it damp and heavy can make it harder to breathe. Humidity can also cause mold to grow faster which is another known asthma trigger. Not all asthmatics are adversely effected by the hot and humid air. Some do better when it is humid. Others notice that the dry hot air sets off their asthma more. It is important to figure out what your individual triggers are so you can take steps to protect yourself.

Response from Leon C. Lebowitz, BA, RRT:

This is a good question and one that many community members and asthmatics, in general, are concerned with. If you’ve ever exercised on a hot, summer day you know that it seems harder to breathe. Add some humidity to the scenario, and breathing is even more difficult. These very same conditions seem to create much more difficulty for those with asthma. It is not entirely clear as to why the heat and humidity affects asthmatics the way it does. Quite simply, hot, humid air is heavier than ‘normal’ air and so, is more difficult to breathe.

These conditions create a chain reaction of events that can raise the body temperature, increase sweating and possibly dehydration, and cause you to breathe at a faster rate. When a person with asthma is having difficulty breathing (no matter what the reason), these conditions can easily exacerbate asthma symptoms, even without actually causing them.

There is also evidence to suggest that hot air can, in fact, irritate the airway and lead to the type of inflammation that triggers asthma symptoms. Researchers found that people with asthma experienced airway restriction when breathing very hot air for an extended period of time while people without asthma did not. This indicates that heat itself may be a cause of airway inflammation and asthma. If humid air is heavier and harder to breathe, the moisture in the humid air actually helps with the absorption of oxygen.

On the other hand, many people with asthma experience asthma symptoms when the air is too dry (i.e. during the winter) because insufficient moisture can also lead to airway inflammation. It seems that air that is either too high or too low in humidity can trigger asthma symptoms. Symptoms typically include wheezing, coughing, shortness of breath, and chest tightness.

Remember too, that heat and humidity are not the only cause of asthma attacks during the summer months. Warm, moist air can create an ideal environment for dust mites to grow and multiply. Mold also tends to proliferate and spread during the summer months for the same reason. Even if you are not actually allergic to these irritants, they can still aggravate your asthma symptoms and trigger an attack.

Regardless of why hot, humid weather creates trouble for people with asthma, experts advise to avoid strenuous activity during these times. Stay indoors as much as possible on warm days and maintain a humidity level in your home below 50%. It is also important for people with asthma to stay hydrated and use their medications as directed.1-4

Response from John Bottrell, RRT:

The warmer the air, the more humidity it holds. Hot, humid air can make the air feel heavy and hard to inhale. Humidity also creates a good environment for both dust mites and mold spores, two very common asthma triggers. Mold spores like a humidity greater than 50%, and so this is why most asthma experts recommend setting the humidity in your home at less than 50%. One way to do this is by using a dehumidifier. Another solution is to use an air conditioner.

Response from Lyn Harper, MPA, BSRT, RRT:

There is no question that many asthma sufferers find the hot weather to trigger symptoms. There may be a number of reasons for this. First, the hot summer air tends to trap more pollutants that can cause breathing problems. Hot, humid air is also the ideal growing environment for mold spores – another irritant to many with breathing difficulties. Pollen is often another problem in the hot, humid days of summer.

Some of the symptoms can be mitigated by using common sense. For instance, if the hot weather is truly bothersome to your airways, try to avoid going out during the hottest part of the day and if you have to go out, avoid activities that are particularly strenuous.
If pollen is a trigger for you, get in the habit of checking the daily pollen count before going out. If it’s high and you must be out in it, make sure you have your rescue inhaler with you and are maintaining a good schedule of all your prescribed medications.
Use your Asthma Action plan! If you don’t have one, you can download one from any number of websites.

Response from Lorene Alba, AE-C:

Extreme changes in weather can definitely make asthma symptoms worse! Everyone with asthma reacts differently to weather; some are triggered by very cold temperatures while others find the cold air relieves symptoms. Same with heat and humidity. Even thunderstorms can affect asthma, especially if there is a change in barometric pressure and you have sinus issues. Quick and drastic changes in temperature (such as leaving the humidity outside and entering a cool building) can bring on sudden symptoms, so always carry your rescue inhaler with you.

Editor's Note: The information in this article cannot be substituted for medical advice. Always consult your doctor before beginning, ending, or changing treatments.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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