Informational Guide

Do Air Purifiers Work With Windows Open?

by Josh M

Suppose you already own an air purifier in your home; natural events such as accidentally burning food and needing to vent the accumulated smoke or accumulated trash may prompt you to open your window. In these instances, you’ll wonder, “Do air purifiers work with windows open?”

Let’s find out.

An air purifier removes contaminants from the air to improve the air quality. Air purifiers are beneficial in all homes but are exceptionally vital for allergy and asthma sufferers.

Air purifiers are composed of two components: an air-drawing fan and filters. As air passes through the filters, which are often constructed of paper, fiberglass fibers, or a mesh, pollutants are caught and neutralized, and the filtered air is fed back into the home.

Air purifiers’ work is to remove allergens, pollutants, odors, and toxins from the air. While an air purifier can operate when the windows are open, it does not perform nearly as well as when the window is closed. The principal reason is that impurities such as allergens are blown into the room with toxic particles, necessitating a more extended purification period.

While certain air purifiers are more efficient than others, and all air purifiers will work to some extent when the windows are open, knowing which air purifier is best for your home is beneficial, and it is critical to use the best air purifier properly.

The following are the top recommendations for operating your air purifier effectively to get the most out of it:

Air Purifier in the Living Room

1. Select An Optimum Place

Air purifiers require ample space, so provide a few meters of clearance to allow for unfettered ventilation. Additionally, because air purifiers come in various sizes, ensure that you get the correct one for the space.

2. Ascertain That The Flow Is Proceeding In The Desired Direction

If the space is ample, direct the purifier’s clean air toward you, where it will be most beneficial. However, this should not be a concern for smaller rooms because the cleaned air will circulate all through the space.

3. Do Not Turn The Air Purifier Off

Not turning off the air purifier is particularly important for households with smokers and people who suffer from allergies, asthma, and other respiratory conditions.

4. Filters Should Be Replaced Regularly

When servicing your home air purifier, always read and adhere to the manufacturer’s guidelines. Ensure that you change the carbon filters annually and clean the washable filters every ten days.

Because air purifier filters are necessary for rhythmic breathing, do not permit them to be clogged with pollutants, as this will leave your air purifier ineffective.

When Do Air Purifiers Work Better: Closed Or Open Windows?

An air purifier performs optimally when windows are closed since external particulates (like pollen, for example) are prevented from entering the room. Therefore, your cleaned air will not escape if you shut any open windows. On the other hand, occasionally opening the window can assist in reducing some of the indoor contaminants.

Moreover, even if the window is open, air purifiers can still do a good job and minimize particulates in the room by 60%, which is better than none at all.

Considerations When Opening Your Window While Using The Air Purifier

It is not possible to keep your window closed 24/7 when your air purifier is running. Some considerations to keep in mind before opening your window while the air purifier is running are:

Outside Environment

If you reside in a polluted region or near areas with car exhaust, smoking, or other sources of pollution, avoid opening your window while your air purifier is working. Additionally, you should avoid leaving windows open during spring due to the high pollen concentration.

The Effect On Your Air Purifier

An air purifier is advantageous when working in limited locations since the disruptions are trivial. It sucks in air, filters it, and then provides clean, fresh air to the space.

It filters the same air that it did moments ago, and the number of particles caught in each filtering attempt reduces with each cycle.

Energy Costs

When you leave your window open while your air purifier is working, fresh air will escape through the open window, while the unclean outside air will come in. When this occurs, you may be inclined to increase the speed and leave the air purifier on longer than usual.

As a result of the decreased effectiveness, you will notice that the air is dirty, prompting you to use your purifier more frequently, which will result in increased energy costs.


It takes only a few hours for your air purifier to improve the air quality in the room. However, with an open window, it will take longer due to the constant circulation of air.

Size Of The Space

When operating an air purifier while the window is open, consider one with a greater coverage area than the size of your room.

Rain Or Wind

If it’s raining or windy outside, keep your windows closed because more air will be blown into the room than when it’s calm.

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 When Should You Put The Air Purifier In The Room If The Windows Are Open?

When it is a freshly painted house, ensure the windows remain open, as among the handful of reasons there is formaldehyde. Formaldehyde is among the most prevalent pollutants found indoors. It is a carcinogen and can be released slowly for more than a decade.

It is good to open the window when the air purifier is working because most air purifiers are ineffective at removing formaldehyde. Due to their physical characteristics, air purifiers have an inferior capacity to purify formaldehyde.

 What Is The Correct Setting Of An Air Purifier If Windows Are Open?

Always turn on the air supply mode of your air purifier when your windows are open.

Where to Place an Air Purifier

People Also Ask (FAQ)

Do air purifiers work around corners?

Keep your air purifier away from walls and corners. The corners can impede the air intake, reducing the unit’s capacity to absorb and clean the room’s air.

Is it better to put the air purifier upstairs or downstairs?

The corridor, which has the highest air circulation in the house, is where you should have an air purifier installed.

Are plants as good as air purifiers in cleaning the air?

Houseplants, while lovely, offer next to nothing in terms of purification in a room compared to air purifiers.

How long should an air purifier run with open windows?

There is no specific time designated for how long you can leave your windows open when the air purifier is on. Usually, it only takes only a few hours for your air purifier to improve the air quality in the room. But with an open window, it will take longer due to the constant circulation of air.

How else can I monitor air quality in the home?

The intensity of air pollution varies in homes. The following are some techniques for monitoring the level of pollution in your home:

  • Invest in a home air quality monitor
  • Conduct a mold examination of the air
  • Install detectors for carbon monoxide
  • Carryout a radon test


Unless extremely necessary, please avoid using your air purifier while your windows are open since it does more harm than good in the long run.

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Last Updated on January 9, 2023

Josh M

My name is Josh and I am obsessed with the HVAC industry. I created this website to help HVAC techs of all levels get the best out of their heating & cooling systems. I have spent thousands of hours studying air conditioners, heaters and home air products so you can learn & buy with confidence. Learn more about the team here.