Gas-phase air cleaners are used to remove a wide variety of contaminants from the air. However, it is often difficult to judge which air
cleaner works for which contaminants and, further, to determine which air cleaner is best for a given application. Most gas-phase air cleaners use
sorbents (e.g., activated carbon) to remove the contaminants from the air. Since sorbents vary in which contaminants they can remove and air
cleaners contain different sorbents in various configurations, it is critical to have test data to document the performance of air cleaners. To meet this
need, ASHRAE has published a new laboratory test standard giving the HVAC market its first gas-phase test standard for air cleaning
devices. This method is ASHRAE 145.2-2011 "Laboratory Test Method for Assessing the Performance of Gas-Phase Air Cleaning Systems:
Air Cleaning Devices."

Five different air cleaners were tested for efficiency and capacity per ASHRAE 145.2 for three different contaminant gases. The air
cleaners were chosen to cover a wide range of the capabilities of currently available devices and include two residential and three commercial units.
All of the air cleaners are sorbent-based, but the sorbents are designed to apply best to different contaminants.

Three contaminants were chosen to include compounds that are undesirable in air but are commonly found in indoor air or in outdoor air
that is entering buildings. These compounds also serve to highlight the capabilities of the test method and the differences across types of air cleaners.
The compounds selected for these tests were toluene, sulfur dioxide, and ozone.

The test results are presented in comparison tables and presented graphically where appropriate. These results include low concentration
‘initial efficiencies,’ breakthrough curves for high concentration exposure, and capacity measurements for the five air cleaners for each of the three
contaminants.