Why your Air Purifier Smells (Musty, Wet Dog, Fish, etc.)

Why does my air purifier smell musty, like plastic, sweet, or even like a wet dog?

That seems like a bad plot in a poor comic. I bought an air purifier to get the exact opposite result!

You just don’t buy an air purifier to make things smell worse.

Just like you don’t eat food to get more hungry. And you don’t buy a car to drive you farther away from your destination.

What causes an air purifier to smell bad?

Here’s one complaint I found online:

“I got an automatic air purifier. In fact, this is my second unit because I thought the first was defective – but when I run this $700 air purifier it smells! It has some kind of semi-chemical smell.”

Barcino from the mothering forum

But are these smells normal?

In this article, we’re going to cover a couple of different topics.

First, some types of air purifiers naturally emit smells. You perceive them as chemical smells. That’s normal.

Then, some types of filters can smell. We’re going to have a look at those as well.

And once you know you have neither a smelly filter nor a smelly air purifier type and your air purifier shouldn’t smell, we’re going to check ALL of the different air purifier smells and how to fix them!

Air purifiers that smell: Ionizers and ozone generators

“Is it ionic? [Ionizers] smell rather unpleasant to me but it is how they are supposed to smell.”

mothering forum member

In this section, my goal is to make sure that your air purifier is not expected to smell.

Two kinds of air purifiers produce smells: Ionizers and ozone generators.

“Ozone, a lung irritant, is produced indirectly by ion generators and some other electronic air cleaners and directly by ozone generators.”


The smell of ozone is similar to the smell of a thunderstorm or “clean” air. Some people don’t like this smell because it can come off as metallic or too sharp.


Is your air purifier an ionizer or an ozone generator?

( You can check this online, in the user manual, or on the packaging )

If yes, it naturally produces a smell.

However, if you have a regular HEPA / activated carbon / UV light filter, it should not smell!

Air purifier smells and how to get rid of them

1. Musty Smell

A musty smell coming from your air purifier can come from excess moisture which causes mold growth inside your air purifier.

You shouldn’t run your air purifier in humid places such as in a bathroom after showering, or next to a humidifier.

HEPA filters absorb water droplets in the air. Combine that with all the bacteria, dust, and pollen on the filter, and mold grows.

How to get rid of the musty air purifier smell

To get rid of the musty smell your air purifier emits, replace the HEPA filter with a new one.

It’s not enough to shake out or brush surface dust off the dirty filter.

Ideally, also clean the filter slot of your air purifier (the space where you insert the filter) with rubbing alcohol, vinegar, or a similar cleaner.

Let your air purifier air out and dry.

Insert your new replacement filter.

The musty smell should be gone.

2. Plastic Smell

New air purifiers often smell like plastic, because of off-gassing. According to a report published in Environmental Science & Technology (Hodgson et al., 2002), common household items (including office equipment, carpeting, and, in this case, air purifiers) can emit a variety of volatile organic compounds (VOCs) including formaldehyde, toluene, and other potentially harmful chemicals.

These VOCs are what you perceive as a plastic smell.

How to get rid of your air purifier’s plastic smell

In general, it’s enough to let your air purifier air out.

Run it for a couple of days. You can also place it outdoors.

If you want, you can wet wipe your air purifier using just water. Do not add any cleaning products, since they may react with the plastic gases coming from your air purifier.

The plastic smell is temporary and should subside soon.

3. Sweet Smell

A sweet smell coming from a new air purifier or a new filter is normal! Personally, I perceive the smell from a brand-new HEPA filter as slightly sweet.

But I like it and it’s not unusual.

After a couple of days of running your air purifier, the sweet smell reduces.

If, however, your old filter starts smelling sweet, this can have the following reasons:

How to get rid of sweet smells in an air purifier

  • Stop using perfumes, room deodorants, or scented candles nearby: Normally, air purifiers are able to filter out scents. A working HEPA + activated carbon filter should not emit any smells.

However, if smells settle on the inside of the filter, the filtered clean air passes over the scent molecules and carries them back into the room.

  • Replace the filter: Often, a sweet smell could be a result of your filter absorbing chemicals from your environment, such as from freshly painted rooms. To solve this, simply replace the filter in your unit.

4. Wet Dog Smell

Weg dog smell does not necessarily come from your dog’s hair being stuck in the filter.

Certainly, this can be the cause. But it’s not necessary.

Wet dog smell usually comes from a combination of dust, hair, and moisture.

How to remove dog smell in an air purifier

The safest way to get rid of the dog smell in your air purifier is to replace the filter.

To prevent the smell from returning, place your air purifier away from humidity coming from the bathroom or kitchen and run it in a dry place such as your living room.

Also, you can place the air purifier on an elevated surface to reduce the amount of dog hair getting into it.

To reduce pet dander in your living space, vacuuming is better than air purifying.

Air purifiers are good at keeping spaces clean, but not at cleaning them.

5. Burning / Smoke Smell

A burning smell coming from your air purifier can come from a part in the electronic circuitry or from a broken fan.

Possibly your air purifier is about to break:

However, in general, air purifiers don’t break easily. They are low-power devices and have only very few components that can break.

How to remove burning smell in an air purifier

If you think your air purifier is about to break, inspect your air purifier’s internal hardware and electronics components.

To do that check my air purifier repair guide and my air purifier noise fixing guide (in case your air purifier makes strange noises in addition to smelling like burning).

After reading these two articles, you’ll know how to fix any air purifier problem.

Another potential cause could be a saturated (smoke) filter that can’t hold on to smoke particles anymore.

The filter might absorb the smoke smell for a while but releases it shortly after.

In this case, I recommend also replacing the filter with a new HEPA filter.

6. Paint Smell

Many of the smells coming from an air purifier at some point got into the air purifier.

Most likely that’s the case for your air purifier. Many people use air purifiers to filter paint smells.

And some are so bold, they get a new air purifier, use it during their renovation, and return it afterward.

So, when you buy a used air purifier, possibly it is loaded with smell molecules from strangers.

How to fix your air purifier smelling like paint

The only way to get rid of the paint smell is to replace the HEPA filter.

If you bought your air purifier new and it smells like paint, probably it’s just off-gassing. In this case, just give it time.

7. Fishy Smell

Interestingly, a fishy smell does not necessarily come from waste or fish. Many electronic components smell fishy.

If your air purifier emits a strong fishy smell, watch out and keep checking that your air purifier works.

Failing electric components are usually not dangerous since air purifiers run on very low wattages.

So, don’t worry about it until your air purifier actually stops blowing air.

How to get rid of a fishy smell coming from your air purifier

To fix the fishy smell your air purifier emits, I recommend you check out my air purifier fixing guide (linked earlier).

Possibly you have to replace an electric component.

Or if you don’t have the knowledge and skills to fix it, get a new one.

I recommend the Levoit Core 300 (click to see my review). It does not smell at all!

8. Cigarette Smell

A distinct cigarette smell (in contrast to general smoke or burning smell) obviously comes from smoking nearby the air purifier.

Air purifiers normally eliminate cigarette smells. However, when you smoke while the air purifier is not running, cigarette smoke can settle on the inside of your air purifier’s filter.

So, clean air passing through the air purifier (entering from the outside), has to pass through the cigarette smoke-covered layer.

How to get rid of cigarette smell coming from your air purifier

To eliminate the cigarette smell coming from your air purifier, just run it longer.

Also, always run your air purifier while you’re smoking.

This way, due to the airstream, smoke can’t enter your air purifier without being filtered.

After a few days of running your air purifier for 8 hours a day, the odor should reduce.

If that doesn’t help, replace the HEPA filter with a new one!

Discuss how this smell can be from the air purifier processing tobacco smoke. Suggest regular filter changes and consider activated carbon filters for better removal of smoke particles.

9. Chlorine Smell

Chlorine smell can theoretically come from your tap water if you use a humidifier-type air purifier.

Or possibly what you perceive as chlorine smell is actually ozone (which we discussed earlier).

If you use an ionizer-type air purifier, it definitely is ozone.

How to fix the chlorine smell coming from your air purifier

HEPA filter air purifiers never smell like chlorine. In fact, they usually are odorless.

If you have an ionizer or even an ozone generator, get a regular HEPA-filter air purifier, and don’t look back.

10. Dust Smell

When your air purifier’s filter is full, it possibly smells like dust. This is usually the case in dry regions. In humid regions, it’s usually a musty smell.

How to fix your air purifier’s dusty smell 

Replace your air purifier’s filter and put in a new one.

In the future, don’t run your filter until it smells. Normally, HEPA filters last 6 months. After that, their dust-collection efficiency decreases by 50% (!).

So, HEPA filters stop working well before your senses start noticing.

11. Food Smell

Food smells usually come from the kitchen. Especially, when kitchen aerosols (oils, waste, etc.) enter the air outflow opening of your air purifier.

If these particles settle there, all the air your filter cleans passes through kitchen grease, which makes the whole purification process pointless.

How to fix food smell in an air purifier

If you use your air purifier in a kitchen, always run it while you’re cooking to prevent particles from entering the wrong opening of the air purifier.

To get rid of the food smell now, replace the HEPA filter.

In the future, always run your air purifier while you’re cooking. Ideally, combine the air purification with an open window to vent the greasy gases out and reduce your air purifier’s load.


Unless you’re using an ionizing air purifier that indirectly creates ozone, air purifiers should never smell.

A smelly HEPA filter-based air purifier indicates either that you don’t run your air purifier while cooking, smoking, etc., or you don’t replace filters often enough.

HEPA filters stop being effective well before you notice it. After only 6 months, they’re only 50% effective.

So, they pick up only half of the particles a new air purifier filter would pick up.

That’s a huge difference!

After 6 months, a HEPA filter merely picks up moisture and dust, both of which result in a musty, wet dog smell.

And on top of that, at that point, most filters stop removing odors.

Nothing pleasurable.

So, replace your air purifier’s filters and you’re good to go!