Do Air Purifiers Work With Windows Open?

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Written By Jamila W.

Air purifiers are among the most common household appliances. Many people have adopted using it thanks to the health benefits and ability to improve indoor air quality. However, do people know how to use them efficiently? Do air purifiers work with windows open? Here we look at how air purifiers work with closed and open windows. We also look at the effects air flow has on the effectiveness of these air purifiers.

Let’s take a deeper dive as you learn more about this.

Are Air Purifiers Effective When Windows Are Closed?

Can you use an air purifier with windows open? Here are facts on the effectiveness of air purifiers in your house. Although most air purifiers are made to be used with windows closed, this does not mean you can’t use an open window.

Some filters use filtration systems where the air passes through the filter, and the particles get caught in the fibers. HEPA filters use this method. It filters tiny indoor pollutants up to 0.3 microns. They stick to the filter, and this includes larger particles. These filters are 99.97% effective. 

When the window opens, the air purifier reduces airborne particles. However, unfiltered air from outside will also be present. 

Why Close Your Window When Using an Air Purifier?

It is better to close your windows using a purifier. People assume that doing this improves performance, but why is this so?

When your air purifier is running, you can keep the purified air inside the room by shutting the doors and windows to prevent it from escaping. Additionally, it makes it possible for your purifier to operate at its most effective level.

Closing the windows frees the room from pollen, dust, carbon monoxide, and other outdoor pollutants. 

Reducing exposure to pollutants is important for maintaining a healthy indoor environment. People living in cities are more at risk as the pollution levels are high. 

 Your room can become contaminated from the outside if your windows are always left open. 

Due to the continuous flow of pollutants, it is simply impossible for the air inside to reach healthy levels. It doesn’t matter if your air purifier runs nonstop. In other words, the air purifier is less effective than it would be when the windows are closed. 

The continuous flow of pollutants in your room also forces your air purifier to operate continuously at its highest settings. 

Because of this, energy is wasted, and electricity costs are higher. The filters on your air purifier will also last less time and require replacement. 

Your air purifier will not work effectively if you leave your windows open. It’s recommended to open windows for a short time rather than leave them open all the time.

When Is the Right Time to Open Your Windows When an Air Purifier Is Running?

opening windows

When using an air purifier, it’s recommended to keep windows closed. However, certain gasses can build up inside a room and need proper ventilation. In these situations, it’s important to open your windows. This reduces the concentration of these gasses before they reach dangerous levels.

When Dealing With Airborne Viruses

It takes a lot of ventilation to get rid of viruses and other pollutants. These harmful airborne particles accumulate in rooms if they have nowhere to go. They increase the chances of you and your family getting sick. Studies have shown that using HEPA filters and ventilation reduces the spread of diseases. 

If you increase ventilation by opening windows, you should use an air purifier with a larger room coverage. This will reduce the effects of opening your windows and doors on the purifier. 

To Allow Air Circulation

Breathing causes CO2 to build up inside closed rooms. This worsens if many people stay in the room and the room is small. Insufficient ventilation can cause the air to become contaminated, making you feel tired and have headaches. 

It’s important to be in a ventilated room when making artifacts with paint or a marker. The same applies to bad smells caused by garbage, burned food, or dirty laundry.

Avoid opening the windows inside the room if the outside air is polluted or you have allergies. In this case, move to a different room every after some time before opening the windows.

Keep your windows closed before turning on the purifier to reduce the amount of pollutants in the air. You can stay in the room and use the air purifier while the windows are open. However, only do this when the outside air is not polluted, and you don’t have any health issues. 

When Preventing the Build up of Formaldehyde

Formaldehyde is a toxic substance that is produced by building materials over time. When a room is hot, the pollutant levels increase. This usually happens after painting the house. 

Formaldehyde is a dangerous substance that can result in headaches, skin rashes, and difficulty breathing. The substance is present in outdoor air, though in small amounts. It can increase to dangerous levels in a closed room. 

Since most air purifiers cannot remove formaldehyde from the air, having one will not do much. Opening a window or door is necessary to remove formaldehyde. This should especially be done if the room is warm, the building is new, or it has recently been painted.

What Should You Do to Get the Most Out of Your Air Purifier?

Air purifiers are great tools for cleaning your air and improving your indoor air quality. However, for them to work effectively, there are things you must do to enhance performance. Let’s take a look at some tips;

Filter Replacement

This is yet another crucial aspect to consider when using an air purifier. The air purifier’s filters successfully get rid of dust and other impurities. As a result, it’s important to clean and replace the filters at the appropriate times. For the air purifier’s best operation, carefully read the filter replacement instructions.

Proper Placement

For the best results, air purifiers require some breathing room. Enough room must therefore surround the air purifier. The air purifier gets an uninterrupted flow of fresh air when there is enough room. For best results, use air purifiers where you sleep or work and the placement position must be right. 

Keep Doors and Windows Shut

Close all the doors and windows before turning on the air purifier at home. The clean air inside a room will escape through windows if left open. In small areas, like enclosed rooms, air purifiers function most effectively. During the day, you can open the windows and doors for proper ventilation and a supply of fresh air. However, when using the air purifier, shut the doors and windows. 

Only Use the Purifier When Necessary

Use an air purifier at the appropriate time to reap the most benefits. Because the air quality is constantly changing, air purification is a continuous process, so the appliance must always be on. The air purifier’s filters, though, might be impacted by this. Utilize an air purifier to its full potential while inside your house. 

Consider Room Capacity

An air purifier works best if running in a room it can cover. Purifiers have different capacities. This means every room needs an air purifier that can cover it well. Consider the ratings when buying a purifier for your room. This will affect the device’s functioning and usefulness to you. The manufacturer usually indicates the capacity of each model.


We have established that air purifiers can improve indoor air quality by removing pollutants. However, the room setup and outdoor air circulation must be considered for these purifiers to function effectively. If polluted air enters your home while an air purifier is running, it affects the air quality. You won’t be able to maintain good air quality.

Closing your doors and windows when a purifier runs ensures that purified air is released back into the room. The air is not blown away by outside airflow. Consider keeping your windows closed for maximum air cleaning effectiveness.