Air purifiers and dry air: everything you need to know

Air purifiers do not generally have the ability to remove moisture from the air. However, it might feel like they do due to increased airflow or the cooling of the air by its fan.

This article answers why an air purifier can make the air (feel) dry. Additionally, read on if you want to know how to make the air drier, or make it more humid.

An air purifier does not dry or remove moisture from the air. However, it can make the air feel drier. Especially when your air purifier is running too fast, or is too big for your room. Air purifiers are often used more in the winter as a replacement for ventilation. However, cold winter air is naturally dry, therefore the air purifier is not the cause of drier air.

Can an air purifier reduce humidity?

Well, the short answer is no. An air purifier does not have the ability to remove moisture from the air.

There are specific appliances designed to do this, called dehumidifiers. A dehumidifier actively removes moisture from the air and has a water tank that will fill over time.

An air purifier does not have a water tank or other means of collecting moisture from the air. So any moisture that might get into the device or its filters is just as easily released again.

If you want to increase the humidity, a humidifier can help increase the moisture content in the air. They are quite cheap on

Cacti prefer dry air. (Photo by LUM3N on Unsplash)

Why does the air feel dry when running my air purifier?

When your air purifier is running for a while, you might feel like the air has become dryer, This is because every air purifier makes the air circulate through the room, similar to a fan, which can make the air feel drier.

In general, warm air makes us feel like the air is more humid. This is because warm air can hold more moisture. Therefore, when the air becomes cooler, for example when you are circulating air through your room with an air purifier, the air can feel drier.

However, air purifiers are not designed to circulate the air. They pull air into the device, but the speed of airflow is greatly reduced by the filters. If you feel like the airflow in your room contributes to a feeling of dry air, it could be because your air purifier is set to a fan speed that is too high for your comfort.

Additionally, the air purifier could be too good for the room you are using it in. This can be the case when your room is small while the purifier is designed for large rooms.

Regardless of how the air in your room feels, the air purifier did not actually remove moisture from the air.

What else can cause dry air?

Dry air is mostly caused by cold air. Therefore it is most common in winter. The outside air is naturally much colder in the wintertime and therefore can’t hold as much water. Since, as described above, warm air can hold more moisture than cold air.

It is possible that you ventilate less during the winter to prevent cold air from entering your home. Therefore, to keep the air fresh, you turn on the air purifier more often. In this way, every time you start using the air purifier more, the air is also drier. However, it is caused by the winter cold, and not by your air purifier.

Photo by Toa Heftiba on Unsplash

So, what does an air purifier do?

An air purifier does not change the moisture content of the air, but it does a whole lot of other things. Namely, an air purifier removes harmful particles and gases from your air, making it cleaner and safer to breathe.

In this way, an air purifier can greatly improve your health and reduce allergies and asthmatic symptoms.

I wrote an article where you can find out if you need an air purifier, you can find it here: How to know if you need an air purifier. Additionally, I recommend reading my article on the disadvantages of air purifiers.

What does an air dehumidifier do?

An air dehumidifier is specifically designed to remove moisture from the air. You can set the device to your preferred moisture level, and it will reduce air moisture to this level and maintain it.

In this way, it can remove musty odor and helps reduce mold growth.

An air dehumidifier comes with a tank that is getting filled with the water extracted from the air. You can simply empty the water tank once it is full. You can read about how a dehumidifier works in my article: How does a dehumidifier work?

If you are looking for a good dehumidifier, I highly recommend checking out, a company that specializes in indoor air quality products. For example, this Danby dehumidifier is excellent (

Additionally, there are several great dehumidifiers for sale on amazon.

For more information about dehumidifier, I recommend reading my article: Dehumidifiers pros and cons.

What does an air humidifier do?

An air humidifier does the opposite of an air dehumidifier. It increases the humidity of the indoor air by evaporating water. This is done by water evaporation. You can often see this as steam coming from the humidifier.

A humidifier is especially useful in winter, when fresh outdoor air is heated indoors resulting in a drop of air humidity to uncomfortable levels. In hot, dry desert climates, air humidity is naturally low.

To increase the humidity of your indoor air without the use of a humidifier, you can install a tray of water near your heating system. In this way, when the air is heated, the water will evaporate and increase the moisture content of the air.

Humidifiers are cheap, and there are several great options available on amazon.

What is the ideal indoor humidity level?

Humidity levels indoors, often called relative humidity, are advised by the ASHRAE (The American Society of Heating, Refrigerating and Air-Conditioning Engineers).

The ASHRAE recommends keeping humidity levels between 30 and 60% for comfortable indoor air.

Furthermore, they recommend more precise humidity levels of 45 to 55 % for people who require the exact perfect humidity to combat allergies or illness.

Why I recommend using an air quality monitor instead

Although an air purifier is a wonderful tool, ventilation is still your best weapon against indoor air pollution. Therefore, measuring the air with a good air quality monitor and ventilating when necessary is an excellent alternative to an air purifier. An air quality monitor has the advantage over an air purifier in that it tests for more compounds than an air purifier can remove. For example, an air quality monitor informs you about the presence of carbon monoxide and radon. An air purifier does not, and can’t remove these compounds from the air.

In looking for the best air quality monitors available, I found a Norwegian company called Airthings, which produces exceptional air quality monitors. They are easy to operate (just wave your hand in front of the device) and send their data to an app on your phone.

Get a 10% discount on Airthings air quality monitors

Readers of this website can get a 10% discount on Airthings devices using my coupon code. With the following coupon code, you can access the discount store: Here, you will get access and 10% off when entering this coupon code: 665381-10OFF.

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