The Honeywell QuietClean Tower Air Purifier captures up to 99% of ultra fine particles such as smoke, dust, pollen, mold spores, pet hair and dander. It also traps odors and Volatile Organic Compounds (VOCs). The washable pre-filter comes installed in the air purifier and removes larger particles from the air. You can use this washable pre-filter, or you have the choice to use the optional Odor & VOC Reducing Pre-Filter that is included with the unit. In addition to capturing larger particles, the pre-filter will also trap common household odors and gases. If you choose to use the Odor & VOC reducing filter, note that it cannot be washed and should be replaced every 3 months for optimum performance. The quiet operation of the Honeywell Tower Air Purifier enables use while sleeping, watching TV or working. It circulates room air 5 times every hour and has electronic push button controls.