Do the Windows Need to Be Closed When the Carbon Filter Is in Use?

If you are only concerned about VOCs and not particulate pollution like PM2.5, pollen or dust, then opening your windows will help ventilate your room and allow VOCs to escape. As such, opening your window can compliment your carbon filter at removing VOCs. If, however, you also have high levels of outdoor PM2.5 levels or pollen etc., then opening your window will allow these pollutants to enter your room. In this situation we recommend you keep your windows closed and use your carbon filter to capture the VOCs, and your HEPA filter to capture the particulate pollution (PM2.5, pollen, dust etc.)