Stand Alone & Inline Air Purification Systems: Whole House Air Purifiers

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Stand alone & inline air purification systems (aps)

Many factors go into choosing an air purifier: area to be treated, pet loads, content & dust burdens, sensitivities, etc. There are basically 2-types of air purification systems available that address particulates and/or chemicals:

Inline APS

Inline aps

An HVAC system with a filter medium at the return plenum or home’s returns.


  • Choice/Cost – Standard on most HVAC systems. There is no initial cost.
  • Convenience – Does not take extra floor space and is usually present in the home.
  • Volume – Allows for the most volume of air to be filtered.


  • Maintenance – Filters difficult to access, changed seasonally & ducts cleaned regularly.
  • Filter Quality/Fit – Low-quality filters and poor fit allowing air loads to get around the filter.
  • Consistency – Is an “on-demand” system running intermittently.
  • Price – Higher-end systems are pricey (compared to stand-alone air purifiers).
  • Chemicals – Does not address Volatile Organic Compounds (VOC’s)

Inline aps

GWE Recommendations for Inline APS

  1. Install/Retrofit a MERV filter with a 7-13 value into existing HVAC systems.
  2. Inline APS systems to consider: Lennox Pure Air © and Honeywell True Clean ©


Stand Alone APS

Stand alone aps

Come in all shapes/sizes and can be used separately or combined.


  • Choice/Cost – Wide range with units ranging from $100 – $500
  • Purification – Multiple filter media/treat particulates & VOC’s / processes far exceed inline systems
  • Convenience – Moveable & used in combination w/inline systems


  • Maintenance – Filters can be expensive & must be changed per manufacturer specs
  • Filtration Area – Units are limited to a determined square footage
  • Choice – Multiple choices make it confusing to decide on the best model


GWE Recommendations for Stand-Alone Air Purification System

  1. Low-Cost HEPA – Honeywell offers reasonably units, but go with the “True HEPA” type.
  2. Multi-Stage – Removes multiple airborne toxins where Austin Air is a great USA line

What Does GreenWorks Environmental Think

IAQ improvement recommendations are complicated (at best) where corrective remedies often involve multiple approaches. Add to it the individualistic needs of occupants and one can see why an IAQ Advisor is essential. But of the utmost importance: “Addressing the source(s) of degraded IAQ should be undertaken first. Relying on air filtration alone as a “cure-all” for sick buildings or mold contamination will not adequately address your IAQ needs.”

Additional Helpful Information

Here are background resources we recommend to put things in perspective:

Article: Analysis of the Effectiveness of Air Filters on HVAC Systems

Paper: Effectiveness of Air Filters/Cleaners in Allergic Respiratory Diseases

EPA: Ozone Generators Sold as Air Cleaners

EPA: Air Cleaners and Air Filters in the Home

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Victor Coppola

Victor Coppola is a Building Biologist with decades of diverse environmental experience spanning natural resource management and contaminated sites to Indoor Air Quality (IAQ) and building hygiene matters. He focuses on the three most prevalent issues degrading today's built environment: Moisture Odor & Mold (M.O.M.). Mr. Coppola and his Team are sought out by individuals and professionals concerned about IAQ to those actually suffering from Biotoxin Illness. His hybrid blend of environmental interests and services enable him to give a unique perspective into today's changing environment. Think your home is killing you, better call Victor and his Team at GreenWorks.
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