Is it safe to use essential oils in the aromatherapy tray, and will it affect the air quality sensor?

Yes, the unit includes an Aromatherapy Tray designed for use with essential oils — simply place an absorbent material such as a cotton ball in the tray and add a few drops of your preferred essential oil. However, the use of scented aromatherapy oil may trigger the VOC sensor to illuminate yellow or red and cause the unit to operate at a higher speed when in Auto Mode. (Page 9)