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Wednesday, June 25, 2008

High & low humidity both bad for asthma

I remember when I was a kid -- like say 10-years-old or so -- and having an asthma attack, and my dad taking me into a bathroom that was full of hot steam. Sometimes he'd have me sit in there for what seemed like a long, long time.

It never worked. In fact, every time I remember my dad doing this with me -- every time in the middle of the night -- I ended up in the emergency room anyway. I do remember feeling more refreshed when I walked out of the bathroom, but I was still short-of-breath.

I also have vague memories of a humidifier in my bedroom. My mom would set that up whether I was having a bout of asthma or not. Despite her efforts to set this up, it never seemed to do anything for my breathing. If asthma was going to occur, it was going to occur.

My parents did this because they were told by my pediatrician that humidity was good for breathing. It was common knowledge back then for doctors to recommend humidity for asthma.

I was discussing this with Jane Sage today, and she said she used to set up ice tents on asthma children routinely. She said scientists and doctors honestly believed they were doing something to help asthmatics.

It was a fallacy. We know that now. Steam works well for inflammation of the upper airway, or croup, but it does not work for asthma.

Many times a mom woke up because her child had a harsh barky cough, or croupy (stridor) expiration, and the child was working hard to breath as a result. A trip to the bathroom usually
worked wonders, and prevented many trips to the hospital. Steam can be soothing to the upper airway.

Cool mists work well for croup too, but not for asthma. If the mom of the croupy child decides to come to the hospital, and it's the middle of winter or a rainy day, the child is usually cured even before she arrives at the hospital.

And, if this croupy child did get admitted, he would be placed either in a cool mist tent or set up with a cool mist aerosol. Now we just use a cool mist aerosol in stead of the tent.

But this therapy seldom works for asthma. In fact, steam, or cool mist tents, or aerosols, have a tendency to make asthma worse. It makes the air thicker, and the patient has a more difficult time inhaling it in.

Still, I have asthma mom's and asthma dad's ask me on a regular basis if they should set up humidifiers for their asthma children, and each time I have to correct the old fallacy that humidity is good for asthma.

That in mind, allow me to introduce you to RT Cave Rule #19:

RT Cave Rule #19: Humidity or cool mists may work wonders for croup, but can make the air difficult to breath for asthmatics. In the hospital, cool mist therapy can be used for croup patients, but not for asthma.
And this is one of the reasons that dehumidifiers and air conditioners can be of benefit for asthmatics (and COPD patients) because they remove the humidity from the air and make it lighter and, thus, easier to breath.

This is my opinion of course. As you will read in a moment, there has been much scientific research on humidity and asthma.

According to Sue Hare and Joe Buchdahl, co-coordinators of the Atmosphere,Climate and Environment Information Programme (see article here, or related article here), areas on the planet that had a relative humidity lower than 50% had fewer "rates of asthma." This problem may be exacerbated in big cities, "because the urban 'heat island' effect caused by asphalt and concrete trapping heat at night."

The report also states that "for every 10% increase in indoor humidity was associated with a 2.7% increase in the prevalence of asthma."

While they may not have had access to these expensive studies, this is also one of the reasons why asthmatics, like Teddy Roosevelt for example, used to report finding relief moving to areas like Arizona where the air is dry all the time.

However, moving to Arizona is no longer recommended, as the increased levels of smog may offset the benefits of the dry air.

Now we have plenty of scientific evidence to support the claim that dry air is better for asthma.

Scientists, according to American Academy of Allergy, Asthma and Immunology (, have determined that high humidity levels have a tendency to be harboring grounds for fungus and molds that might bother asthmatics. Plus, when the humidity is greater than 50%, the amount of dust mites in the air is increased. For this reason alone, humidity is no longer recommended for asthmatics by pediatricians.

Likewise, if you have ever been in a hospital, you probably noticed how dry it is in these places. Noses get dry, hands get chapped and start to crack (especially in the winter months). The reason is because the humidity of hospitals is kept low as to not create a harboring ground for fungus, molds and dust mites.

That's also why the air is cranked up in the summer months too. Sure, you may be cold, but this is good for disease control, and great for asthmatics.

As per The American Lung association, "Air-conditioning can help. It allows windows and doors to stay closed. This keeps some pollen and mold spores outside. It also lowers indoor humidity. Low humidity helps to control mold and dust mites."

On the other hand, also according to, if the relative humidity is less than 15%, this may trigger an excessive cough for asthmatics. Thus, it is recommended for "asthmatic patients to aim for a 'happy medium' relative humidity in their homes, monitoring their home humidity regularly with a reliable gauge."

The Center for Disease Control and Prevention recommends humidity be set between 35% and 50%.

I suppose you could use a convenient humidity monitor (like this). (I am not endorsing this product, I just coincidentally found it while doing my research tonight. In fact, I didn't even know it existed until a few moments ago.)

Personally, I do not have an air conditioner at home, nor do I control my humidity, but often times in the dog days of summer I wish I could afford it.

Likewise, working in the nice cool, clean air environment of a hospital was one of the best incentives of me deciding to be an RT.

(Allergy Be Gone has an excellent related article. This is also where I got that cool picture from.)


Amy said...

This is so great--good, clear information about the humidity/asthma angle from someone in the business. I'm gonna throw it into Friday Links tomorrow b/c I think other parents could really benefit from it. said...

I totally agree! When the relative humidity reaches 40 or 50% I feel the effects almost immediately. The higher it goes, the harder it is to breath.! In fact, I consider humidity a major trigger for many of my exacerbations.

For the most part, the SF bay area is OK , unless were hit with a sub tropical storm ( or wildfires)

If I had my way , Id live in a drier environment.

Nice post!

Anonymous said...

Very cool. I'm glad Amy linked it, because it definitely confirmed my issues with hiking in humid air.

sleetod said...

Thanx, I have problems just air drying a shirt in the main living space of my home b/c of the moisture in the air. The last time I went to the doctor with asthma symptoms he suggested a humidifier and when I told him of past experiences w/ them he stood staring at me in disbelief, telling me that he had never heard of this!

Unknown said...

Reading this helped me understand how to make my son comfortable as I can. Love this! Thanks