The Guardian Air PHI CELL is designed to help eliminate sick building syndrome risks by reducing odors, air pollutants, and cold and virus causing germs through a patent pending Photohydoionization^® (PHI) process. The PHI Cells are easily mounted into existing air conditioning and heating systems. When the HVAC (heating, ventilation, & air conditioning system) is in operation, the PHI cell uses an Advanced Oxidation Process to reduce the airborne contaminants.