Humidifier vs Dehumidifier vs Air Purifier

This article discusses the differences between a humidifier, a dehumidifier, and an air purifier. We also discuss under what conditions can they be helpful for you.

Why should I even consider either one?

Humidifiers and dehumidifiers

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.

Air purifier

What is an air purifier and why do we need it?

Air purifiers are devices which, as the name suggests, clean the ambient air. There are mainly two types of air purifiers, namely:

  • High efficiency particulate air (HEPA) filters
  • Air ionisers

These air purifiers can have additional components, such as a UV light chamber, activated charcoal filter, and so on, which are mainly designed for widening the spectrum of the device’s efficacy against various pollutants.

Many people wonder whether an air purifier is the right investment. However, in the current scenario, where air pollution is prevalent and worsening with each passing day, especially in urban areas, air purifiers are very vital.

Air pollution is the presence of undesired substances in the form of solids, liquids, or gases, which are suspended in the ambient air, and can adversely affect human health.

These pollutants can be especially harmful if present in the indoor environment. The average human being spends more than 90% of their total lives in an indoor environment, with more than 80% of it inside a building.

Indoor air, just like outdoor air, is susceptible to pollution. Indoor air can get polluted when pollution from outdoors infiltrates through openings such as doors, windows, cracks, seeps, etc.

Indoor air can also get polluted from indoor sources, which can arise from things such as furniture, household items, solvents and dyes, spores from mold and mildew, combustion of fuels and firewood, and hobbies/activities such as smoking, etc.

The pollutants generated from these sources have been shown to adversely affect human health, and continuous exposure to elevated concentrations can cause many serious issues, such as cancers, respiratory and cardiovascular disorders, and even death.

This is where air purifiers come in. They help to get rid of the pollutants in the indoor air, thereby keeping it clean and fit to breathe.


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.

Which one should you invest in?

In the case of humidifiers and dehumidifiers, 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.

However, it is absolutely vital to invest in an air purifier as well. Although air purifiers can get rid of allergens and other pollutants that are associated with humidity, they themselves cannot affect humidity.

Furthermore, using an air purifier in a high humid condition can also cause damage to the device. Therefore, in such conditions, it is absolutely vital to have an air dehumidifier along with the air purifier.


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. 

However, when it comes to air purifiers, it is important to have one irrespective of the humidity conditions, as certain pollutants in the indoor air cannot be dealt by humidifiers as well as by dehumidifiers.


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


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