Asthma causes your airways to constrict, and humid air can make it more difficult to breathe. You can keep humidity at reasonable levels indoors and take steps to protect yourself outside in humid weather.

Humid air can make breathing more difficult, especially for people with asthma who may not be able to breathe as easily without coughing, wheezing, or shortness of breath.

This article will explain why humidity affects your breathing, how it can affect those with asthma or other conditions, and how you can help your breathing in this kind of weather.

Breathing in humid air activates nerves in your lungs that narrow and tighten your airways.

Humid air is so saturated with moisture that your sweat doesn’t evaporate efficiently to cool you off. That’s why you feel hotter and stickier on humid days.

What to know about humidity

The Environmental Protection Agency (EPA) recommends keeping indoor humidity at 30% to 50% for the most comfort. Anything over this range is usually considered humid.

Humid air is stagnant enough to trap pollutants and allergens like pollen, dust, mold, dust mites, and smoke, which can make your asthma symptoms flare up.

However, having too little humidity, where the air becomes too dry, can lead to irritation and dryness in your respiratory tract and cause more issues for people with asthma.

Humidity affects air quality in these specific ways that can be more concerning for people with asthma:

  • Dust mites: These mites, which live in furniture, carpets, and bedding, thrive at humidity levels of 50% or higher. Their dead bodies and waste can also set off asthma attacks.
  • Mold: You’ll often find mold in damp places like bathroom ceilings and flooded basements, and it’s more likely to grow in places with 60% or higher humidity. Breathing it in can flare up your asthma if you’re sensitive to mold.
  • Sudden temperature changes: Research from 2015Trusted Source notes that people with asthma are more sensitive to sudden and extreme temperature changes.
  • Ozone: You may hear about ozone action days, when you’re encouraged not to drive gas-using vehicles, mow your lawn, or use other gas-related items. This type of gas is more common as humidity rises, and it can irritate your airways and lungs and worsen your asthma symptoms.

Research indicates that climate change will continue to affect people with asthma more dramatically as time goes on.

Research from 2015Trusted Source emphasizes the importance of clinical guidance on this issue for people who may experience worsening respiratory symptoms as weather patterns change.

In 2023, the EPA released a peer-reviewed report noting that climate-driven changes are expected to increase the amounts of asthma by 4% to 11% each year, and that children will begin developing asthma more often.

A 2024 study involving mice also noted that high humidity and the air pollutant nitrogen dioxide, both tied to climate change, can make asthma symptoms worse. Research will likely continue on this topic.

The easiest way to tell if humidity triggers your asthma is to see if your symptoms flare up when the weather gets hot and sticky. Common asthma symptoms include:

Learn more about asthma symptoms and how to prevent or manage them.

The EPA recommends keeping indoor humidity at a comfortable 30% to 50% setting.

Where possible, try these tips for controlling indoor humidity:

  • Turn on your air conditioner and close your windows during the day.
  • At night, when the temperature and humidity drop, open the windows to let in fresh air.
  • Install a dehumidifier, which pulls excess moisture from the air.
  • Turn on a fan in your bathroom, especially when you shower.
  • Make sure your home has good insulation. It will keep your home warm in the winter and cool in the summer.

To prevent humid weather from triggering your asthma symptoms, it can help to do the following:

  • Avoid going outside on humid days, especially when the air quality is low.
  • If you have to be outside, use your rescue inhaler before you go.
  • Don’t exercise outdoors during the hottest times of the day.
  • Drink lots of water and wear loose, light clothing.

Moderating humidity indoors isn’t always possible, and you can’t do anything about outdoor humidity and weather.

If you experience asthma attacks or more symptoms as a result, you can manage them through different treatments. Consult your healthcare team for the best guidance on managing asthma.

Reducing your exposure to humidity may help reduce asthma symptoms. The EPA recommends keeping the humidity inside your home set between 30% and 50%. When it’s humid outside, stay indoors with your windows closed and your air conditioning turned on, if possible.

If you still have trouble managing your asthma symptoms, even with medication, speak with your doctor. They will likely need to review your asthma plan and make some modifications.