How Often to Change the Air Purifier Filter: 3 Dangers If Don’t Do This in Time

How often to change the air purifier filter so that it continuously cleans well? Air Cleaners keep dust particles, dander, and pollutants away. But if the filters get clogged, they will not be able to do their job properly.

Let’s take a closer look at the various filter change term, the signs that they need to be replaced, and what dangers await you if you don’t do it in time!

Quick Answer

There are some terms to change filters:

  • The air purifier’s HEPA filter should be replaced within 12 months.
  • The activated carbon filter can last over 3 to 6 months.
  • The washable filters and pre-filters should be cleaned every 3 months.

However, these intervals are general. Continue reading to learn about the factors that can affect the changing time and what are the indicators of dirty filters to get an exact time figure.

The Main Reason Why Filters of Air Purifiers Need to be Replaced

Indoor air quality can be five times worse than outdoors as stated by U.S. Environmental Protection Agency. It consists of small particles which must be cleared such as:

  • Dust
  • Dander
  • Bacteria
  • Allergens
  • Pollutant

I recommend reviewing 8 Best Air Purifier with Washable Filter

Air purifiers can remove and trap them in the filter. But you should know:

  • The filters can capture up to 99.97% of particles as small as 0.3 microns.
  • Doing so can block their holes.
  • A clogged filter can’t function correctly and won’t clean the air properly.

So you need to clean or replace the filters regularly. Let’s take a look at signs that your air filter must be changed.

Signs to Know that the Air Purifiers filter Needs Replacement

Nowadays, many air purifiers come equipped with a red light indicator to signal when it is time to replace the filter. In case you miss the alert or forget to change it, look for the following points to know:

Signs to Know that the Air Purifiers filter Needs Replacement

  1. Musty or moldy odors in the air.
  2. Weakened air flow from the machine.
  3. A grey and dirty-looking filter.
  4. Worsening allergy or asthma symptoms.
  5. More pet dander moving around.
  6. Increased dust around the home or office.
  7. Unusual noises coming from the air purifier.
  8. Air purifiers behave differently.
  9. Difficulty remembering when the filter was last changed.

Factors That Can Affect Air Purifiers Filter Replacement Time

Filter replacement intervals vary depending on air conditions and their type. Typically, you should change them every 3-12 months, I covered it more deeply below. However, it is a possibility that it needs replacement before that time if:

  1. You run your air purifier frequently.
  2. Pollutants have increased inside the house due to cooking or deep cleaning.
  3. Live in the city center that has more pollution.
  4. You live somewhere that experiences wildfire season.
  5. Construction is going on nearby.
  6. Experience a rise in allergy or asthma symptoms.
  7. Have thick-coated pets.
Factors That Can Affect Air Purifiers Filter Replacement Time

If you feel that the air purifier is underperforming, check the filter to see if it is clogged. In case the replacement alert is on, do not ignore it. Change the air filter right away.

What is the Best Time to Replace Filters?

It is noted that the following schedule is the most recommended by the users according to the specific filter types:

  • Pre-Filter: Clean every month. Change when it is worn, not more often than in 3 months.
  • UV Light: Switch UV-C blub every year.
  • Activated Carbon Filters: Replace in 3 to 6 months.
  • HEPA or True HEPA filter: Switch within 1 year, especially in Public Spaces. Can extend up to 18 months if it is placed in the home.
  • Permanent Filters: Clean whenever necessary. Replace only when damaged.
How often to change the air purifier filter

Important Note: These intervals could be more or less, as it depends on air quality and the number of people that use the space. If you are unsure, perform the actions below.

Check the Filter for Clogs or Dust Buildups

Here’s what needs to be done:

  1. To check if your air purifier filters need to be replaced, open up the housing and look at the filter itself.
  2. If it looks excessively dirty and clogged, it may be time for a thorough cleaning or replacement.
  3. During this process, it is recommended to wear a mask and gloves to protect yourself from the pollutants that may be released as you touch the filter.
Check the Filter for Clogs or Dust Buildups

See if the Filter Replacement Indicator is On

A simple way to know if the filter should be replaced is to check the indicator light.

  • You will find it near the air purifier’s control panel.
  • Opt for a protective mask and thoroughly clean the filter.
  • Once cleaned, reset the indicator by pressing and holding it for a couple of seconds.
filter indicator

Note: It is only possible in devices with indicator lights. Most new models have this feature.

Read Also: Best Levoit Air Purifier: 12 Top Models for a Clean Air

Advantages of Regularly Changing the Air Purifier Filter

Breathing in cleaner air is essential for healthy living. This is why Air Purifiers have become a necessary appliance. In order to let it perform to its true potential you must clean its filter in time.

Below are a few of the advantages why:

Advantages of Regularly Changing the Air Purifier Filter

1. Improve Indoor Air Quality

Regularly changing your air filter leads to better indoor air quality. It captures dust, allergens, and other harmful large particles. This helps alleviate allergy and asthma symptoms, leading to easier breathing at home or in the office.

2. Less Dust Meaning Less Cleaning

Air purifier filters can help catch dust particles in the air, preventing them from settling on surfaces in your home or office. This means you’ll spend less time cleaning and enjoy cleaner surfaces.

3. The Air Purifier will be Working Properly

A clogged filter puts more strain on the components of the air purifiers, leading to damage over time.

  • By changing the filter every 12 months, or sooner if necessary, your machine will work as intended without added stress.
  • This will save you money on potential repairs and ensure that your device works properly.

Are Air Purifier Filters Reusable?

It is important to note that not all air purifier filters can be washed and reused.

  • Check the label: Only do so if the filter’s label explicitly states that it is washable. Attempting to wash a non-washable filter can damage it.
  • Use a vacuum: If unsure, use a vacuum to remove dust residue from the filter. Keep in mind that HEPA filters, trap particles throughout their fabric and not just on the surface.
  • Do not wipe the top layer of the air filter: It can release trapped particles into the air, making the air quality worse.

For more insights, check out this video.

YouTube video


How long do air purifier filters last?

How long air purifier filters last depend on upon filter type. Pre-filters last 3 months, Carbon filters last 3 to 6 months, and HEPA filters last 12 months.

Should you leave the air purifier on all day?

You should leave the air purifier on all day if experiencing poor air quality. Just remember to change the filters on time.

How often should you change the HEPA filter in the air purifier?

You should change HEPA filters within 12 months or before if the air filter replacement alert turns on.

How often should I clean the air purifier?

You should clean the activated carbon filters every three months, HEPA filters every 12 months, and permanent filters after 3 months.


In order to know when should replace the old air filters, consider their type. The true HEPA filters can be changed within 1 year. The activated carbon filter will need cleaning in 3 to 6 months. Wash the pre-filter in 1 month and replace it in 3 months.

The time can vary if the air purifier is placed in a public space. Also if furry pets reside with you, construction is happening nearby or you live in a busy metropolitan. Let me know when was the last time you changed yours.