The 300a is a two stage air purifier with a negative ion generator and a dual-ceramic ozone plate filter. The 300a s ozone function can oxidize the particles in the air and eliminate indoor contaminates. By significantly reducing various particulates in the air such as smoke bacteria dust and allergens the 300a can greatly reduce the irritation of these contaminants to allergies. The unit is made of solid natural wood no pressed wood or laminate exterior. There are also no costly filters to replace! Save hundreds off retail price and get the Atlas Air Purifier for your home or office. Negative ions can be created around the clock to keep down dust and particles that cause allergies. The activated oxygen has a separate control. Activated oxygen is normally kept at modest levels in occupied spaces. To remove major odors the unit may be adjusted to a higher level for a period of time. Some use a timer to completely deodorize the home or office while away. Unused O3 reverts back to O2 in about an hour.