How Do You Know if the Air Is Dry or Humid and Whether You Need a Humidifier or Dehumidifier?

They sound almost similar, but they perform different functions.

A humidifier adds moisture to your indoor air. The dehumidifier removes excess moisture from the air to lower the humidity level. They are the exact opposites of each other.

So, how do you know if you need a dehumidifier or humidifier? When the moisture levels in your indoor air drop below 40%, you need to run a humidifier. When the air is too moist, you need to dehumidify the air. If the humidity is higher than 60%, you need to remove the excess moisture to prevent the growth of mold.

Here is a detailed guide to let you know which appliance you need for your home when the humidity increases or decreases.

How do you know if you need a dehumidifier?

To know the humidity level, test the air with a hygrometer. If it is higher than 55%, dust up your dehumidifier and keep it ready.

A dehumidifier gets rid of excess moisture when humidity levels are high. You will know if you need one when you notice some of the signs caused by high humidity.

Most places experience high humidity in the summer. However, it is not uncommon to use a humidifier in summer.

Keep reading to see a few symptoms of high humidity in the house, but first, you can order a good dehumidifier from

1. Condensation on the windows and walls

This is the earliest sign of excess humidity. If your windows and walls have condensation, it means there is too much moisture in the air.

If you have any doubts about it, just use a hygrometer to find out the humidity level. If it is higher than 60%, you need to remove it.

2. Musty smell in the house

The musty smell comes from growing mold. Mold and mildew thrive in dark and humid places. Therefore, if you get that musty smell in your home, you probably have a mold infestation.

The musty smell can come from other sources. For instance, if you do not clean the house regularly, you might experience a musty smell.

3. Mold on the walls and other items

Mold appears as spots on the walls, floors, clothes, and other parts of the home. It is the worst stage of a humid environment.

This allergen grows mostly if there is a leak, poor drainage, or water intrusion from a high water table.

Image of Honeywell dehumidifier

Here, not only will you need a dehumidifying unit, but you will also need to deal with the cause of the excess humidity.

Mold is a serious indoor allergen. Its spores can cause exposure symptoms in babies and asthmatic attacks in people with the condition. Besides, mold and mildew damage clothes, walls, furniture, and other items.

4. Damage to your items

Has the wall paint started to peel off, the wood is rotting, and the metal wiring is rusting? It is the high humidity that is causing damage to your property. Excess humidity can also cause damage to electronics.

You need to dehumidify the air. Failure to remove the excess moisture will result in more damage.

5. High indoor humidity level

You can measure the humidity level using a hygrometer. If the reading is above 60%, then you will need to bring it down before it can cause any damage.

6. Increased allergies

If you start getting allergic reactions, chances are that it is because of mold and bacteria that grow in humid environments. You will start seeing many signs of mold toxicity.

When should you run a humidifier?

A humidifier increases moisture when the indoor air is dry. It is recommended that the humidity level is above 30%.

However, the level depends on factors such as your location, climatic conditions, and the insulation of your home.

Image of a commercial humidifier

Some of the signs of dry air include:

1. Respiratory problems

One of the signs of dry air is respiratory problems. These include persistent coughs, allergies, sinus infections, and nose bleeding.

The nasal passage needs moisture for it to function correctly. If you feel that your nasal passage is too dry, you can’t breathe properly, you start coughing, and your mouth feels dry, you need to humidify the room.

2. Dry skin, chapped lips, and itchy eyes

Dry air makes the skin dry. The eyes start to itch, and the lips crack. The skin needs moisture to remain soft. If you start having rashes on the skin, it could be due to exposure to dry air.

3. Damages items

This is one of the long-term effects of dry air. If the wooden furniture is cracking, the wooden floor starts to develop gaps. The wood contracts after losing moisture.

Check your paint too. It could start peeling or flaking off. If that is the case, you need a humidifier to increase moisture. You can buy a good one on

4. Static electricity

Do you see sparks on your clothes when you wear them or when you are combing your hair? You might also notice them on the furniture. This static electricity occurs because of dry air.

If you have static electricity in the house, it means the air is dry. Running a humidifier to raise the humidity levels is going to rectify this problem.

Also read my articles on:

Mold toxicity symptoms to watch out for

Mold symptoms in babies

Health effects of high humidity


How do you know if you need a dehumidifier or humidifier? It is very simple if you know the symptoms to look for.

In most places, you will need to reduce indoor air moisture in the summer. You will need to increase it during the winter.

To dispel any doubts that you might have in your mind, please test your indoor air using a hygrometer. Also, static electricity, dry skin, chapped lips, and itching indicate low humidity.

On the other hand, black mold, musty smell, condensation on the windows, and mildew are indications of too much humidity in the air.