Can I Use an Air Purifier With Windows Open

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An air purifier works by filtering pollutants and contaminants like allergens, pollen, dander, and microbes from the air, and circulating fresh, clean air. But, on a warm spring day, you may want some fresh air to wash through your home. But how does this affect your air purifier?

You may be asking yourself, “can I use an air purifier with windows open?” We will look at the answer to this question and a few other facts that you should consider with your air purifier. So let’s get right to it!

Does an Air Purifier Work With Open Windows?

The short answer to this question is yes, but not very well. Before going further, let’s look at what “work” means. An air purifier works by continuously cycling and filtering the air in your home. 

When you open the windows in your home, the purifying process is interrupted and your home will be exposed to whatever allergens are present in the air outside. So before you open windows, keep in mind that you will be starting the purification process over again.

For example, when the refrigerator door is open, it still operates, but not very well, and if you leave the door open for a while, the cooling process starts again once the door is closed. This is the same with your air purifier with open windows.

Should You Always Keep Windows Closed With an Air Purifier?

This is not at all the case. There are a few things to consider when deciding whether to open your windows or not. Here’s what to ask yourself:

Is the outside air clean?

The first thing to consider is whether the air outside is smoggy, dirty, or polluted. Keeping your windows closed is necessary if the surrounding environment has trash, smoke, exhaust fumes, and unhealthy particles.

Will the window be open for hours?

The amount of time you leave the window open is a determining factor for whether your purifier can work efficiently or not. The longer a window is open, the less effective the purifier is. It takes a few hours to filter a room, so think about this interruption.

If you only plan to leave the window open for a few minutes because, for example, you have cleaned your floors with a strong agent, and you need airflow, this should not be a problem. But keep the window open only as long as is needed.

Open window to the back yard with small shed.

Consider These Factors Before Opening Windows

Here are a few things to keep in mind before you open the windows in your home.

Indoor Environment in Your Home

Because you use an air purifier, it is safe to assume that your indoor air quality is quite good now. So it is also probably safe to assume that you are opening your window to let something out, not let something in. 

We gave the example of the cleaning agent, but perhaps you burned food and need to let the smell of smoke out? Or perhaps your garbage bag ripped and you have smelly garbage juice all over the floor. Or maybe you spent the day painting the walls and need to let the fumes out? These are great reasons to open a window – but limit it to that – one window.

Many people like opening their windows in summer to listen to the birds chirping or their kids playing in the yard or the swimming pool. But this counteracts the efficiency of your air purifier, which you are running for a good reason. It would be better for you to sit outside and enjoy a few minutes of outside air, then go back inside to the filtered, pollen-free air.

Impact on the Air Purifier

The simple reality is that it is easier for your purifier to work in a closed, confined space. The disruptions are less frequent, allowing it to be more efficient. The air your purifier filters is the same air that was filtered a few minutes prior. The particles trapped with each pass of filtration decrease with every pass.

When the air that the purifier has to clean is limited, you increase the efficiency and the amount of time the unit needs to filter a whole room. There may be another additional problem you haven’t thought about yet: if you clean additional air due to open windows, you could be lowering the lifespan of your air purifier. This is something to consider too.


As we said earlier, the time it takes to purify an entire room is determined by air space. So if you are only going to open the window for a few minutes, that’s fine. Anything longer than that, and you are affecting the unit’s efficacy.

Although we are considering whether you can use a purifier with windows open, we also need to consider if you should. If you have respiratory or allergen issues, the time you spend suffering from low-quality air can impact your health.

Typically, it takes a few hours for the air quality in your home to improve using a purifier. So if you have any health concerns, keep in mind how long it will take to rid your home of these allergens and pollution to restore clean, fresh air.

Energy Costs

In the same way that running an AC unit with a window open wastes energy, so does running a purifier with the window open. You will need to increase the fan speed and run the purifier for longer to achieve the same result, all of which cost money. Although most purifiers do not use much electricity, these small extra amounts add up over time.

Final Thoughts

So, as you can see, an air purifier can work with the windows open, but it will not be very efficient at removing the allergens in your home until you close the window. Our suggestion is that you switch the purifier off when your windows are open, then switch it back on once you close them so that all of the pollen and allergens can be filtered.

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