Your air purifier is most efficient when all the doors and windows are shut.

Does this mean you should never open a window when your air purifier is running?

No. Ventilation plays an important part in the improvement of your indoor air quality.

We advise you to ventilate your home every day by opening the windows for at least 10 minutes to let in some new air. If the outdoor air is highly polluted, try ventilating when the outdoor air quality is at its best, by checking the outdoor air quality levels in your Blueair app. During this temporary ventilation, you can leave your air purifier on. Once you close the window, the air purifier will lower the indoor pollutant levels.