How Long To Run Air Purifier: All Day or All Night? 

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Breathing clean, fresh air makes any room a comfortable living space for everyone. And, having a good air purifier can go a long way in making sure that the air you breathe is free from dust, odors, and airborne pollutants. But if you’re new to the world of air purifiers, you’re definitely wondering how long you should run it.

The amount of time it takes an air purifier to clean indoor air depends on the size of the unit and the size of your room.

That said, the air quality in our spaces changes all the time, and everyone’s environment is unique. If you have an allergy, for example, you may want to run it for a longer period of time than usual. However, if the air quality inside is noticeably clean, you can limit it to only a few hours.

Below, we’ll talk about how long you should operate your air purifier during the day. We’ll also address some of the concerns that other curious air purifier owners, like you, may have.

How Long Should You Run an Air Purifier?

It’s generally fine to run an air purifier continuously for 24 hours, especially for larger rooms with bad air quality. 

If you have a small space, running it for at least 6-8 hours per day should do. However, if you have a busy household and tend to prepare food all the time, keeping your unit running throughout the day helps capture particles and remove odors from the air as well.

A new innovation in the air purifier market also makes it possible for many models to run for long periods of time. Many of them feature built-in smart sensors. This helps monitor indoor air quality and determine the ideal time to run it.

In addition, most air purifiers remove particles and irritants like pet dander, lint, and other air pollutants in  2 minutes. But then again, it depends on the size of the room and your unit. You must also consider the following factors:

Filter Type

HEPA filters are a minimum standard for all air purifiers, while some may even include an activated carbon filter. That might sound good, but, the more filters in the air purifier, the slower the airflow. This is due to the increased resistance, which will eventually affect the cleaning speed of the unit.


How long an air purifier cleans the air in a room also depends on its speed and clean air delivery rate (CADR), which is expressed in cubic feet per minute (CFM). It indicates air purifier performance by calculating the amount of air it cleans per minute based on the particle size.

The CADR is lower when you set your unit to its lowest speed, while it takes full advantage of the delivery rate at high speeds. A higher CADR also indicates that your unit doesn’t need to operate for long hours if it suits the size of the room.

However, running an air purifier at full speed isn’t always ideal because of high noise levels. It’s ideal to run your unit at maximum speeds during the day when the noise level is less noticeable.

Room Size

You can expect an air purifier to work faster if its specifications suit the space. It wouldn’t make sense to place a small unit in a larger room, as it will have to work for hours to completely clear the air of harmful particles and dust. See some of our favorite air purifiers for large rooms.

Extraction Rate

This is the amount of air that your air purifier can clean per hour, and it also affects its cleaning speed. The extraction rate is measured in terms of air changes but is quite hard to measure.

If your air purifier has 4 air changes per hour, it may clean the air in your room as quickly as a unit rated for 2 air changes. It’s safe to run your air purifier at such extraction rates for 10 hours a day, especially when you’re working and sleeping.

How to Keep Your Air Purifier Running Efficiently and Speed Up Cleaning Time

How to Keep Your Air Purifier Running Efficiently and Speed Up Cleaning Time

Air purifiers are hardworking machines for improving indoor air quality, making your home healthier and more comfortable for everyone. So, it’s important to use them properly and give them the TLC they deserve. It helps them run efficiently and extend your unit’s lifespan. Here are a few things you can do:

Check Filters

Your air purifier’s filters play a crucial role in trapping particles from the air. Unfortunately, they can accumulate dust over time. And leaving them dirty can limit their efficiency and put more strain on your motor, which means it needs to work harder, and eventually raise your electric bills and maintenance expenses.

Checking on your HEPA filters and cleaning them regularly can help extend the life of your purifier. If your unit has multiple filters, you can use a vacuum brush to clean the pre-filter and do so every 2-3 weeks. Replace the HEPA filter every 6 months or so if it doesn’t seem like it’s working properly.

Proper Placement

Some homeowners tend to overlook it, but how you position your purifier in a room can affect how effectively it cleans indoor air.

Placing the air purifier unit in a corner, for example, simply won’t work as efficiently as placing it at the center of the room. A good rule of thumb to follow is to place the air purifier at least 2-3 feet away from any walls or furniture.

Clean Your House

Cleaning your home regularly helps your unit speed up the process of maintaining good indoor air quality.

Close your doors and windows

You’ll want to limit the amount of polluted air your room is exposed to while using your unit. Closing your doors and windows close keeps outside contaminants out, leaving you with only clean air.

Is It Expensive To Run an Air Purifier?

It depends on how long you run the unit, its size, and the average cost of electricity (cents per kWh) in your area. That said, most purifiers are designed to be energy efficient so running one in your home may be a relatively small expense. However, the cost may still add up if you use it for long periods of time.

A trick that can help save you money on running an air purifier is to use it during off-peak periods. You may want to turn it on between 9 p.m. to 9 a.m. when people use the electricity less. This could help reduce tariffs.

But we all have different reasons for needing to run an air purifier. So, if you’re constantly having respiratory issues, you may run it during normal hours.

Should You Run an Air Purifier All the Time?

Though they’re generally designed to run continuously, you don’t have to use them all the time. But if your space has poor air quality, you’ll benefit from running your air purifier 24 hours a day. Just keep in mind that air purifiers consume more power and may require frequent air filter replacement.

Is It OK To Leave Air Purifier on All Night?

You can run your air purifier all night. Sleeping with your air purifier on can improve the quality of your sleep. It keeps airborne irritants from accumulating overnight, which can cause allergic symptoms. Plus, nothing beats waking up in a better mood, focused, and rejuvenated.

However, depending on the model, it can generate noise during bedtime. You may set it to the lowest setting to minimize the noise though many air purifiers are relatively quiet.

Is It OK To Leave an Air Purifier on All Day?

Yes, you can have your air purifier running all day. However, it is important that you follow the manufacturer’s usage and maintenance requirements.

Make sure that the air filters are always clean. Remember, those parts accumulate dust and allergens over time, so it’s important that you clean them at least once a month to keep your unit running smoothly.

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

It depends on the air quality, room size, and metrics like the wattage and CADR (clean air delivery rate) of the unit. On average, an air purifier takes roughly 30 minutes to 2 hours to circulate and purify the air in a standard-sized room.

That said, know that an air purifier doesn’t really clean the air in one go. Instead, it constantly circulates and cleans the air in a room if you give it some time. This is why most of them run for 24 hours to maintain the consistent air quality in a room.

Final Thoughts

While running an air purifier 24/7 is recommendable, you don’t have to do so if your indoor air quality is relatively clean. Leaving it on for 6-8 hours a day should be enough. And consider the size of your room and the model you have.

Got any more questions? Feel free to contact us and we’ll be glad to help!