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How Long Should You Run An Air Purifier?

Last updated March 23, 2023

As an experienced content producer and editor, James makes sure our content is always compelling, clear, and useful. He also leads the production team and makes sure our writers have everything they need to keep doing their best work. On his off days, you'll find him outside hiking or searching for stone circles.

Our verdict:

We recommend running an air purifier while you’re in the room but if you’re concerned about reducing Covid-19 viral load in inhaled air, then you should definitely run your unit 24 hours a day.

Air purifiers are designed to run continuously and doing so will provide you with the best possible air quality at all times. This is particularly important for anyone with health issues such as allergies, asthma and weakened immune systems. 

Modern units are surprisingly energy efficient, especially considering the benefits they offer.

If you have recently purchased an air purifier (or are planning to buy one), you’re off to a great start to improving your health and overall quality of life. However, you may be confused about when and how long you should run the unit. 

This article will explain when it makes sense to keep your unit continuously running VS the cases where perhaps it can be overkill to do so. 

We’ll also try to put your mind at ease about the cost of running a unit non-stop so that you can enjoy excellent air quality all the time.

How Long Should You Run Your Air Purifier?

An air purifier can remove 45% of pollutants from the air in most bedrooms in approximately an hour and a half. While it may seem logical that running an air purifier for short periods would be effective, we also need to consider that pollutants are being added to the air constantly. 

Dust, pet dander, and lint are continually being produced within our homes, along with all the contaminants working their way from the outside. This means that if you’re battling that type of pollutant in the air, then you want to make sure to keep your air purifier running while you’re in the room.

In cases where you have a serious outdoor pollution issue or if you want to reduce the risk of Covid-19 transmission in a busy space, then you should consider allowing your air purifier to run 24-7 to ensure your air is always at the peak of cleanliness.

This is also an excellent idea if you live in an area with high levels of outdoor pollutants such as wildfire smoke, in an older home, or have people living in the house with compromised immune systems. 

However, many healthy individuals use an air purifier to help tackle air quality issues that are not always present, such as weed smoke or cooking odors. In those cases, we recommend that you use your air purifier while you’re engaging in an activity that generates pollutants and/or when you’re in the room where you are looking to improve the air quality.

If you are wanting to sleep well with an air purifier running, then be sure to look at what we think are the best bedroom air purifiers.

Is It Safe To Run an Air Purifier All the Time?

Air purifiers are designed in a way that they can run non-stop. Many people will find this the easiest method, as they don’t even need to think about the machine – especially in cases where you own an air purifier with an auto mode that kicks in when needed. 

Another benefit of running the air purifier 24/7 is that when a constant noise is present, the human brain adapts to filter out that noise. A brain is an efficient machine; once it recognizes an environmental sound as unimportant, it will no longer waste processing power on noticing it. In contrast, when you constantly switch an air purifier off and on, your brain must adapt to the sound each time. 

However, if you choose to run your air purifier all the time, it’s still essential to keep on top of changing the filters as needed.

How Long Does It Take for an Air Purifier To Clean a Room?

While the average time it takes for an air purifier to clean a room is around 90 minutes, this can vary based on the room size. A small room may only take half an hour to clean, while a larger room may need 90 minutes or more.

The other factor for how long it takes an air purifier to clean the air in a room is the overall performance of the unit. 

One way an air purifier is rated is based on the room’s square footage. This method isn’t always accurate, as a room with a high ceiling will take longer to clean. However, if you have standard eight-foot ceilings, it will provide an adequately precise measure.

Another system of rating is the Clean Air Delivery Rate (CADR). This tells the user how efficiently the air purifier works to remove pollutants.  The CADR number measures how many cubic feet of air are cleaned per minute. 

Remember: A high CADR air purifier will clean a room faster. 

At first glance, it may seem like a low CADR will be fine for a small space. However, even in this case, a high CADR machine will be better at cleaning the air and will require less maintenance in the long run!

It can be helpful to compare CADR numbers when shopping to find the most effective machine, as this rating should be listed on every box. 

Ideally, however, you should be able to test the units performing their job in the same space. Now, this is not something you are likely to be able to do so we recommend you have a look at our air purifier reviews before you commit to buying a unit. We test all the products we recommend in the same space performing the same task, that way we can pinpoint the ones that are ACTUALLY good.

Can I Sleep With an Air Purifier On?

Some users may feel that running their air purifier is not as important while sleeping or that the machine will disturb their sleep. However, you certainly continue to breathe while you sleep, and pollutants are likewise still being added to the air!

Running the air purifier while you sleep ensures eight hours of quality breathing. As such, a machine may help your sleep rather than hinder it. 

Here are three reasons why running your unit could benefit your sleep: 

1. Clean air reduces snoring

Allergens in the air can irritate the upper airways and increase allergy symptoms, causing blockages. Any blockage or inflammation in the oral or nasal passageways can result in snoring. 

Even if you live alone, snoring can negatively impact your sleep quality— whereas if you have a partner, it can also affect theirs! A constant flow of clean, fresh air can reduce these symptoms and help to minimize snoring. 

2. White noise helps you sleep

Contrary to what many people think, white noise generated by an air purifier can aid sleep

White noise is a constant, steady, low-frequency sound and can be so beneficial to sleeping that people will even use white noise generators or apps to create soothing, ambient frequency. The human brain adapts to white noises, so we don’t consciously notice it after some time. 

As discovered in a 2005 study, white noise also has a masking effect on other noises that disturb a person’s sleep due to their abrupt nature. Therefore, white noise is helpful to people living in places that are “too quiet” or overly noisy. 

Air purifiers create a white noise level of around 40dB through the motor running and blowing air and the noise stays at a constant level — making it an ideal sound for sleeping. Finally, many units also include a Sleep mode for those that prefer the lowest noise levels. 

3. Nice, fresh smells improve sleep quality

Air purifiers are a great way to reduce odors within the house. Removing odors from the bedroom can help improve sleep by making the sleeping environment more comfortable. 

For example, a poll conducted by the National Sleep Foundation found that 71% of people reported better quality sleep on fresh, nice-smelling sheets. 

This goes to show how vital smell is to sleep! If the smell of sheets can make that much difference, then the overall smell in the room is sure to be beneficial as well.

🙋 “But what about energy consumption? Won’t it be expensive to run my unit all night long?”

Nighttime is typically designated as ‘off-peak’ for electricity tariffs. Many people choose to run appliances at night precisely because it significantly affects their energy bills. The same rule applies to your air purifier. Overnight may be the most cost-effective time to run your unit and you’ll receive the same benefits of an air purifier to your air quality during this period. 

Calculate the Cost of Running Your Air Purifier

Compared to other appliances, air purifiers are relatively energy-efficient devices — particularly when it comes to the modern devices on the market today. 

When running an air purifier all day, the machine doesn’t need to work very hard and may only require 10-30W. An energy-efficient unit could cost you only cents per day when running it non-stop!

Here is a calculator that will help you determine how much it would cost to run your unit all day to help you decide if the benefit outweighs the cost. 

Final Thoughts 

Good air quality is invaluable to your health. 

Suppose you’ve invested in an air purifier or are planning to do so. In that case, it’s important to realize that running the device continuously will give you the most from your purchase. 

Not only can it keep the air you breathe at the highest quality throughout the waking hours, but it will also significantly improve your sleep quality at night. These two things are likely to benefit your overall health and well-being.

Finally, with a modern unit, this benefit will only increase your expenses by cents a day — which we feel is money very well spent!


Cooper, E. et al. (2021). Use Of Portable Air Purifiers In Homes: Operating Behaviour, Effect On Indoor Pm2.5 And Perceived Indoor Air Quality.
National Sleep Foundation. (2023). Bedroom Poll: Summary of Findings. 
Riedy S.M et al. (2021). Noise As A Sleep Aid: A Systematic Review.
Solomon, S.G, Kohn, A. (2014). Moving Sensory Adaptation beyond Suppressive Effects in Single Neurons. 
Stanchine, M.L et al. (2005). The Influence Of White Noise On Sleep In Subjects Exposed To ICU Noise.