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Air purifiers have different built-in features with some capable of indicating when your indoor air is clean and when it has pollutants that need cleaning. If yours does not have an air quality indicator, you must be wondering how long you should leave the purifier running.
You should run your air purifier all the time (24 hours a day) to keep indoor air clean and free of allergens. Most air purifiers take 30 minutes to 2 hours to clean indoor air, but air pollutants can still enter the house and contaminate indoor air if you switch the unit off.
Some air purifiers such as the Dyson TP04 have some advanced features that make the appliance turn on and off depending on the quality grade of indoor air.
Is it safe to run an air purifier all the time?
It is safe to run your air purifier all the time since the units are built to run nonstop without any danger of failure or damage. Even when leaving the house, leave the unit running so that you can come home to clean breathable air.
Indoor air gets quickly contaminated, so, turning the air purifier on and off does not get rid of contaminants effectively.
How long should you run an air purifier?
Air purifiers vary in specifications. The quality of air filters, CADR rating, and air displacement or circulation ability can determine how fast the device can remove airborne pollutants and purify air.
So, how long should you run an air purifier to notice a difference in air quality?
Run your air purifier all day (24/7) to maintain clean air in your room. Most air purifiers are able to remove dust and other pollutants in 30-120 minutes. Since allergens such as lint, dust and pet dander can be constant, leave the air purifier to run all the time to get rid of the irritants.
How Fast Does an Air Purifier Work?
It can take anywhere between 30 minutes and 2 hours for an air purifier to purify air in your house, but that depends on the efficiency of the appliance. Air purifiers with higher clean air delivery rate are faster at purifying indoor air than those with a lower CADR specification.
Therefore, to determine how long you need to keep your air purifier running in your house, consider the features and qualities of the model you are using.
Here are the factors that determine the performance of your air purifier
The Clean Air Delivery Rate is a way of measuring how a residential air purifier performs. This rating determines the volume of air your air purifier cleanses per minute depending on the size of the particles.
In determining the CADR specification, the air purifier is tested against pollutants of different sizes, specifically, smoke, dust, and pollen.
CADR is a representation of the air flow (CFM) multiplied by the filter’s efficiency. If, for example, an air filter is rated to have a 200 CFM with 80% efficiency, the CADR would be 160.
A higher CADR specification means that you don’t have to run your air purifier for so long to purify air in your room (if the room sizing is correct).
Every air purifier is effective only when placed in a room the size of its specifications. For example, the Dyson Pure Cool TP04 air purifier is highly efficient when placed in a room that measures 800 sq. ft.
If you place it in a bigger room, you might have to run the air purifier for a much longer time to clean and purify air and make it safe for allergy sufferers.
In short, air purifiers also need to be placed in a correctly sized room to be effective, just the same way you would size an air conditioner’s BTU rating to a room in square feet.
Air extraction rate
Air extraction refers to the amount of air a purifier can clean per hour. This rate determines how fast the appliance will clean indoor air. This metric is usually measured in terms of air changes.
For example, an air purifier rated to have 4 air changes per hour can purify indoor air twice as fast as an air purifier rated to have 2 air changes if both are placed in correctly sized rooms.
In this sense, an air purifier with an extraction rate of 4 changes per hour will run for just one hour and successfully purify air in a room it is placed in.
Type of filter
HEPA filters are a standard in most air purifiers nowadays. Some purifiers have activated carbon filters in addition to standard filters. The more the number of filters, the higher the resistance there will be, meaning air will flow much slower.
This, by a small percentage, affects how fast the air purifier cleans air to remove dust, pollen, pet dander, dust mites, and other pollutants.
Therefore, air purifiers with several filtration levels may need to run for more than 2 hours to clean air within their specified room sizes.
How often should I run my air purifier?
It is recommended that you run your air purifier all day for optimum results. However, there are times when you cannot run it 24/7, turn the purifier up on the highest setting for at least 30 minutes prior to using the room.
In about 1 hour, most air purifier units can clean up air and remove up to 95% of dust particles and other airborne pollutants.
After cleaning the air on the highest setting, turn the unit down 2-3 levels and allow it to run for the entire time you will be using the room. If you turn it off, the air will be contaminated to the original dirty state within just a few hours (1-3 hours).
Should I sleep with my air purifier on?
It is a great idea to use an air purifier in your bedroom to make sure the air you breathe is of high quality all-night-long. It is safe to sleep with the unit running when placed in a safe spot where it will be effective at cleaning air in your bedroom.
For the unit to be effective, place it in a location where it is able to take in dirty air and release purified air towards you (especially if it has a jet focus mode like Dyson TP02 and TP04 models).
It is recommended to run your air purifier 24/7 (all day and all night). While the unit can clean 95% of impurities in indoor air within 1-2 hours, it will only keep it clean while running.
Every house has air vents that allow air from outside to enter your rooms. This air is usually laden with odors, dust particles, pollen, and other allergens. If you turn off your air purifier, the air will become dirty as impurities from outside build-up.
HVAC tech with over 30 years of experience. Retired and doing repair work on the side around Madison County, AL.