How Long Should You Run an Air Purifier?

An air purifier helps finish unwanted smells out of your room, leaving you with clean air free of toxins. Also, air purifiers eliminate airborne pollutants, allergens, and toxins that can cause allergies and respiratory diseases. But how long should you run an air purifier?

Essentially, an air purifier can take 15 minutes to two hours to purify a specific room. However, dirty particles continuously accumulate in the room. Therefore, you might need to run the air purifier for a longer period.

Factors That Determine How Long You Should Run an Air Purifier

Some air purifiers can clean out all the air in a particular room every 15 minutes. However, since particles keep finding their way into the house, you cannot run the unit for just 15 minutes and expect great results.

The amount of time you need to run an air purifier depends on several factors.

Room size

Each air purifier is effective when placed in a room that is within the recommended size. For example, if an air purifier is ideal for a 480 square-foot room is put in a 600 sq. ft. room, you might have to run the air purifier for a much longer time to clean the air.

We always advise our readers to go for an air purifier whose recommended room size is equal to or bigger than their largest room. This way, it will work even better when moved to smaller rooms.

The air purifier’s ACH rating

ACH stands for Air Changes per Hour. This represents the number of times that an air purifier sanitizes all the air in the room within one hour. So, this is a good indicator of how quickly the air purifier works.

How long should you run an air purifier - Levoit LV-PUR131S Smart True HEPA Air Purifier
Levoit LV-PUR131S Smart True HEPA Air Purifier

For example, an air purifier with an extraction rate of 6 air changes per hour will run for one hour and completely clean air in a room. Therefore, you should run an air purifier with a high ACH rating for a lesser duration than the one with a low ACH rating.

Type of filter

The higher the number of filters, the slower the air flows, thus taking longer to purify the air. Therefore, it is recommendable to use air purifiers with few filters so long as one of them is a HEPA filter.

However, this should not be a deal-breaker because the more the filters are, the better the filtration system. Besides, there are special filters for specific pollutants. For example, activated carbon filters remove smoke, odours, fumes, and VOCs (volatile organic compounds).

How much dirt is in the air?

The dirtier the air is, the longer you’ll need to run your air purifier to clean the air thoroughly.

Notably, some air purifiers like Dyson TP04 have some specific features that turn the device on and off depending on air quality. Hence, such automated purifiers will run for longer and at higher fan speeds when the air is too dirty.

Running costs especially electricity bills

If you are concerned about spending too much on your electricity bill, you could run the air purifier for a few hours a day to clean the air or when you feel that the air is too dirty. However, air purifiers do not consume a lot of electricity.

Despite the low energy consumption by air purifiers, here are a few things you can do to ensure that you reduce running costs even further:

  • If possible, only run the air purifier when the air is likely to be dirty. Besides, if you have a smart air purifier, you can make use of the scheduler.
  • Make use of the timer to run the air purifier for a set time (some air purifiers lack timers, though).
  • Change or clean the filters on time to avoid overworking the air purifier.
  • When shopping for an air purifier, look for the Energy Star seal or logo. Energy Star-rated air purifiers will help you a great deal if you are concerned about huge running costs.
  • Another thing to consider when looking for an air purifier is air quality monitoring. A smart air purifier allows you to select Auto Mode, whereby it runs at high fan speeds only when the air is very dirty, thus saving on energy costs.

Below is an example of a smart Levoit air purifier:

How Long Should You Run an Air Purifier?

For maximum benefits, you should run your air purifier 24/7. This will help a great deal especially if you or any other occupants suffer from asthma and allergies. However, you can follow our guidelines above if you are not an allergy sufferer.

If you can run the air purifier for a lesser duration, you’ll save money in the long run. You will change filters less frequently while paying slightly reduced electricity bills.

On the other hand, if you intend to run it 24/7, make us of Auto Mode during the day (if yours has one). Here, the fan speeds will adjust automatically depending on how dirty the air is. Alternatively, you can manually select the lowest or medium fan speed.

At night, you can switch to Sleep Mode. This feature is available in most air purifiers. To help you sleep better, the fan speed reduces to minimize noise while the air remains clean.

Besides, some air purifiers have a relaxing night light as well as pink noise.


How long should you run an air purifier? For the best results, run your air purifier all the time (24 hours a day). This will help keep your indoor air free of airborne pollutants such as dust, dust mites, pollen, smoke, odours, gases, fumes, and VOCs.

This will help a great deal if you suffer from allergies and asthma attacks. However, if you just want to clean the air and you don’t have allergies, you can consider the factors we have outlined in this article.

However, an air purifier needs some time to clean the air in a room. So, you should run it for a few hours a day at least. Check out our compilation of the top rated air purifiers in Canada for more information on air purifiers.

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