Air Purifiers can be very helpful in removing the dust, dander, pollen and dirt from the air that circulates through your force air system. Depending on your household your furnace filter may not be enough to remove these particles. The biggest factor is that there are many different types of furnaces filters with different MREV ratings so depending on which you use, that will determine how effectively you are removing the dust, pet dander, pollen and other microorganisms within your home.
Most air purifiers will do a good job of removing large particulates like those mentioned previously. The added benefit is that many air purifiers also can remove odors, gases, and bacteria also. They do this by various means including using higher MERV rated filters, UV lights and catalyst that reduce concentrations of airborne contaminants, like viruses and mold and bacteria. Many households find that using an air purifier does clean the air in their home and that the differences are measurable, especially for those families who do suffer from allergies or exposure to allergy irritants like, smoking, pets, etc. Most hospitals and large institutions use air purifiers to help manage the air in such tightly sealed environments.
To help you choose which air purification is right for your home and to learn more about Air Purifiers consult a professional HVAC company. They can run you through the various options to fit your heating system and give you several models to choose from as well provide the installation.