Humidifier vs Dehumidifier

This article discusses the differences between a humidifier and a dehumidifier, and under what conditions can they be helpful for you, or can also be disadvantageous.

Why should I even consider either one?

Have you ever wondered why your nasal passage feels irritated while breathing, or why mold and mildew growing in certain areas of your house.

These are all caused due to variation in the humidity levels of your indoor environment. Humidity is measured in terms of relative humidity (RH).

An optimal range of RH is between 30% to 50%. Anything above this promotes the growth of unwanted microorganisms such as bacteria and mold, while anything below this can make the air dry and cause irritation to the skin and respiratory passage.

Usually, climate helps to regulate humidity levels both outdoors as well as indoors. However, in certain seasons, the humidity levels may deviate considerably from the optimal range. 

In such situations, humidifiers and dehumidifiers come in handy. Humidifiers add moisture to the air when it is too dry. A dehumidifier takes moisture out of the air when it is too humid.


Working mechanism

Humidifiers are devices that increase the humidity of the indoor environment. These are generally used in dry seasons such as winter, when RH levels dip below the optimal range.

There are two different types of humidifiers: cool-mist humidifiers and warm-mist humidifiers, which are also known as steam vaporisers.

They both contribute moisture to the air in the same way. Aside from personal choice, there isn’t always a benefit to one over the other.

Cool-mist humidifiers break up water into tiny particles that then enter your air as water vapor. The water starts cold and stays cold, so they can help cool your air, too.

Steam vaporisers heat normal water to its boiling point, then cool the steam and release them in the indoor environment. They can also be used with inhalants or essential oils that may be helpful for people with allergies or asthma.

How humidifiers help

As mentioned before, humidifiers make the room humid, which is essential in dry seasons. This is because dry air can act as an irritant to the nasal passage and the respiratory passage.

Furthermore, dry air can also contain particular allergens that can trigger asthma flare-ups, as well as cause issues such as:

  • Sore throat
  • Nosebleeds
  • Bronchitis
  • Sinus inflammation (sinusitis)
  • Cold
  • Influenza

Which type of humidifier should you invest in

Cool-mist humidifiers are safer than hot-water humidifiers because they do not utilise hot water, which might burn you if you drop it. As a result, they are safer to use in the presence of youngsters.

However, if the humidifier isn’t cleaned regularly or correctly, cold mist might transmit airborne germs or virus material. Before releasing steam, steam vaporizers boil away germs or pathogens in the water.

If you have children or if you have pets, a cool-mist humidifier may be the best option. If hot water from steam vaporizers is spilled, it might cause burns.


Working mechanism

Contrary to what humidifiers do, dehumidifiers dry out the air. This is essential in certain seasons such as summer and spring, when the ambient humidity levels rise up to 60%.

A dehumidifier operates by using a fan to suck warm air currents into its coils. Warm air condenses when it passes through the machine’s chilled coils, leaving condensation inside the dehumidifier.

As the condensation gathers, one droplet of water at a time, it falls into a dehumidifier-connected storage tank. Through the opposite side of the machine, cooler, drier air is sent back into your house.

An air dehumidifier should be able to reduce the humidity in the air to 30 to 50 percent relative humidity. Many dehumidifiers come with a metre that monitors the relative humidity in the area where they’re installed, and you may adjust the humidity to the desired percentage.

How dehumidifiers help

Mold and dust mites can grow in excessively wet air, producing spores and droppings which can cause allergic responses and trigger severe asthma symptoms. As a result of nerve reactions, hot humid air can cause constriction of the respiratory passage.

Dehumidifiers can also help when:

  • You have chronic or seasonal allergies, such as hay fever.
  • You have just moved somewhere new where your allergy symptoms are worse.
  • Your home smells wet or there are excessively moist areas of your home
  • Your home has seepage problems or leaks during or after it rains.
  • You see water vapor in your air at home or notice that the air feels heavy and wet
  • You are allergic to dust mites
  • You have too many pests like spiders or silverfish.
  • Your clothes take a long time to dry when you line-dry them.
  • You find yourself coughing or having runny noses frequently.

Various types of dehumidifiers

There are mainly four different types of dehumidifiers, which include:

  • Refrigerative
  • Electronic
  • Desiccant
  • Ionic

We have already discussed the working mechanism of the refrigerative dehumidifier. It is also the most commonly available type of dehumidifier.

The other common type of dehumidifier is a desiccant dehumidifier. This is a considerably more powerful dehumidifier, however it’s mostly used in commercial storage for medicines, food, and chemicals. 

It can lower humidity levels by 45 percent to 1%, however it does so by relying on thermal energy (natural gas or steam) rather than electrical outlets. 

Desiccant dehumidifiers employ chemical attraction instead of condensation to reduce humidity levels.

What benefits do these devices offer

Both, humidifiers as well as dehumidifiers are helpful under certain conditions. They can help with respiratory issues, which include:

  • Asthma
  • Bronchitis
  • Allergies
  • Cold

We shall discuss these in more detail.


A humidifier can help wet dry air, which can irritate your airways and make you more susceptible to illnesses. Dry air can also trigger asthma attacks in people prone to it.

A dehumidifier can help to remove excess moisture from the air, making it easier to breathe and preventing airborne contaminants from becoming suspended.


Mold and bacteria produce spores that, on inhaling, can cause bronchitis, which makes it difficult for people to breathe. Dehumidifiers help to keep mold and bacteria in check, thereby preventing bronchitis.

Dry air acts as an irritant to the respiratory passage, which in turn can trigger bronchitis. In such scenarios, it is helpful to have an air humidifier, as it helps to keep the respiratory passage moist.


Under moist conditions, mold, bacteria, and dust mites thrive. They produce substances and droppings which on inhaling can trigger allergic reactions. 

Air dehumidifiers help to keep the air in the indoor environment dry, which in turn keeps mold and dust mites in check.

In dry air, dust particles can easily get suspended in the indoor air. Due to this, dry air can trigger dust-related allergies on inhalation.

Humidifiers help to remove suspended particles from the ambient indoor air, therefore reducing the risk of allergies in dry seasons.


Humidifiers can help to keep in check cold symptoms such as coughing, wheezing, and so on.

Which one should you invest in?

In order to make an informed decision about which device you should invest in, it would be ideal to first estimate the climatic conditions of your area.

For places in the coastal areas, the annual humidity levels are usually high. Therefore, for people living under such conditions, it would be wise to invest in an air dehumidifier.

On the contrary, for cold places, or places at a high altitude, the ambient humidity levels are typically low. Hence, one should invest in an air humidifier in order to counter dry air conditions.


In this article, we discussed how humidifiers and dehumidifiers work, and they are effective in dry seasons and seasons associated with high humidity levels, respectively.

We see that both devices have a shared benefit, especially when it comes to respiratory health.


Should I also buy an air purifier?

Yes, you should also buy an air purifier. These devices help to remove the pollutants and odors present in the ambient air, thereby making the room less stuffy.

HEPA filters with an activated carbon filter as well as a germicidal UV light chamber are the best option for getting rid of the stale air smell in a relatively short amount of time.

However, it is important to note that air purifiers should not be used in high humidity conditions, as humid air is heavier than normal air, which causes overworking of the air purifier, thereby decreasing its efficiency.

Another reason for doing so is that the mold spores entrapped within the filters can start proliferating in there itself, which in turn can exacerbate the air quality.

Will an air dehumidifier get rid of the musty smell in the basement?

Air dehumidifiers do not get rid of the musty smell in the basement. However, these devices keep in check the sources that cause musty smell in the basement.

Basement areas are defined as enclosures placed directly under the building. These rooms are usually built below ground level, so they are prone to leakage problems, and usually lack adequate ventilation and heat. 

These factors play a major role in increasing the relative humidity of the room, which favours the growth of mold and mildews. 

This is where air dehumidifiers come in the picture, as they help dry out the air. These devices, as the name suggests, lower the humidity of the indoor environment, therefore keeping the air dry and hampering the growth of mold.

Do air fresheners also help in alleviating the air quality?

No, air fresheners do not help in alleviating the air quality. These products simply mask the odors present in the ambient indoor air. 

However, they do not tackle the root cause of these odors, and once the effect of air fresheners fades away, the odors associated with poor air quality also returns.

Do humidifiers help in the case of mold and mildew formation?

No, humidifiers do not help in the case of mold and mildew formation. Rather, they can exacerbate the condition even more.

Mold and mildew only grow in humidity levels of more than 50 percent. However, using a humidifier will further provide the humidity levels required by the mold and mildew to proliferate, and also spread to other areas of the house.

Other FAQs about Air Humidifiers that you may be interested in.

Can humidifier put water in lungs?

Humidifier vs Dehumidifier vs Air Purifier


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